Upload
l10nass
View
222
Download
0
Embed Size (px)
Citation preview
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
1/16
Epilepsia, 48(1):43–58, 2007Blackwell Publishing, Inc.C 2007 International League Against Epilepsy
Anticonvulsant Mechanisms of the Ketogenic Diet
∗Kristopher J. Bough and †Jong M. Rho
∗Center for Drug Evaluation & Research, Food and Drug Administration, Rockville, Maryland;
†Barrow Neurological Institute, Phoenix, Arizona, U.S.A.
Summary: The ketogenic diet (KD) is a broadly effective treat-ment for medically refractory epilepsy. Despite nearly a centuryof use, the mechanisms underlying its clinical efficacy remainunknown. In this review, we present one intersecting view of howthe KD may exertits anticonvulsantactivityagainst the backdropof several seemingly disparate mechanistic theories. We summa-rize key insights gleaned from experimental and clinical studiesof the KD, and focus particular attention on the role that ketonebodies, fatty acids, and limited glucose may play in seizure con-trol. Chronic ketosis is anticipated to modify the tricarboxcylicacid cycle to increase GABA synthesis in brain, limit reactiveoxygen species (ROS) generation, and boost energy productionin brain tissue. Among several direct neuro-inhibitory actions,
polyunsaturated fatty acids increased after KD induce the ex-pression of neuronal uncoupling proteins (UCPs), a collectiveup-regulation of numerous energy metabolism genes, and mito-chondrial biogenesis. These effects further limit ROS generationand increase energy production. As a result of limited glucoseand enhanced oxidativephosphorylation,reduced glycolytic fluxis hypothesized to activate metabolic KATP channels and hyper-polarize neurons and/or glia. Although it is unlikely that a singlemechanism, however well substantiated, will explain all of thediet’s clinical benefits, these diverse, coordinated changes seempoised to stabilize synaptic function and increase the resistanceto seizures throughout the brain. Key Words: Ketogenic diet— Epilepsy—Metabolism—Polyunsaturated fatty acids.
The ketogenic diet (KD) is a high-fat, low-protein, low-
carbohydrate diet that has been employed as a treatment
for medically refractory epilepsy for 86 years. The “clas-
sic” KD is based upon consumption of long-chain satu-rated triglycerides (LCTs) in a 3:1–4:1 ketogenic diet ratio
(KD ratio) of fats to carbohydrates + protein (by weight).
The vast majority of calories (>90%) are derived from fat.
While clinical implementation of the KD has varied from
center to center (Kossoff and McGrogan, 2005), diet treat-
ment generally begins with a period of fasting followed by
gradual increase in calories to a target KD ratio of 3:1–4:1.
This is conducted in the inpatient setting over the course
of several days, where blood glucose, urine ketones, and
several other metabolic variables are closely monitored.
The hallmark feature of KD treatment is the production of
ketone bodies by the liver. Ketone bodies provide an al-
ternative substrate to glucose for energy utilization, and in
developing brain, also constitute essential building blocks
for biosynthesis of cell membranes and lipids.
While the clinical effectiveness of the KD is widely
accepted, surprisingly little is understood about its under-
Accepted October 24, 2006.
Address correspondence and reprint requests to Kristopher J. Boughat FDA – Center for Drug Evaluation & Research, MPN 1 – Room1345, 7520 Standish Place, Rockville, MD 20855, U.S.A. E-mail:[email protected]
doi:10.1111/j.1528-1167.2007.00915.x
lying mechanisms of action. Although some studies sug-
gest that dietary constituents or metabolites have direct
anticonvulsant effects, emerging evidence indicates that
adaptations to chronic administration of the KD result inimproved seizure control. These data suggest that the KD
activates several endogenous metabolic and genetic “pro-
grams” to stabilize and/or enhance cellular metabolism,
and that these fundamental changes help counter neuronal
dysfunction associated with seizure activity.
MECHANISTIC INSIGHTS FROM STUDIES
OF KD EFFICACY
The anticonvulsant efficacy of the KD has been ex-
amined in various acute and chronic animal models of
epilepsy over the years (Stafstrom, 1999). Clinical andexperimental studies have provided key insights into im-
portant treatment-related variables and, when considered
together, these studies have helped direct mechanistic re-
search. Commonalities between clinical and experimen-
tal studies of efficacy are summarized in Table 1 (adapted
from Stafstrom, 2004).
Based on vast clinical experience, almost any diet that
produces ketonemia and/or diminished blood glucose lev-
els can induce an anticonvulsant effect. Ketogenic diets
comprised of either LCTs (Freeman et al., 1998; Vin-
ing et al., 1998) or medium-chain triglycerides (MCTs;
43
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
2/16
44 K. J. BOUGH AND J. M. RHO
TABLE 1. Translational correlations of ketogenic diet (KD) efficacy
Variable Experimental findings Clinical findings References
Age Young rats and mice P40 at dietonset
Infants, children and adolescents
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
3/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 45
are administered in ratios of ≥3:1 (Freeman et al., 2000),
and higher KD ratios increased both clinical (Dekaban,
1966; Livingston, 1972) and experimental anticonvulsant
efficacy (Bough et al., 2000b). Similar to the KD ratio,
increasing the extent of CR resulted in improved seizure
control in epileptic mice (Greene et al., 2001), irrespec-
tive of the type of diet that was restricted (Eagles et al.,2003). In general, extra calories in the form of carbohy-
drates or proteins translate to additional metabolic sub-
strates for gluconeogenesis and diminished KD efficacy.
Breakthrough seizures are believed to result from overes-
timation and administration of excess calories (Freeman
et al., 2000). As such, CR may share common anticonvul-
sant mechanisms and adjunctively optimize KD efficacy.
In rodents, maximal seizure control develops 1 – 2 weeks
after initiation of a KD (Appleton and DeVivo, 1974; Rho
et al., 1999; Bough et al., 2006). Similarly in humans,
clinical efficacy does not reach its zenith in many patients
until after 2 weeks (Dekaban, 1966; Freeman et al., 2000).
One notable feature of the KD is the rapid occurrence of
breakthrough seizures and loss of ketosis when carbohy-
drates are introduced (e.g., after a child sneaks a cookie;
Huttenlocher, 1976). As a result, the KD must be strictly
enforced in order for efficacy to be maintained. However,a
breakthrough seizure may not necessarily translate to a to-
tal loss of seizure control. Studies have shown that, despite
an abrupt discontinuation of the KD, the increased resis-
tance to seizures waned gradually when switched back to
control (Bough et al., 2006) or even high-carbohydrate,
antiketogenic chow (Appleton and DeVivo, 1974). This
decline in seizure threshold generally occurred over 1 – 2
weeks, mirroring the onset of seizure protection (Apple-ton and DeVivo, 1974; Bough et al., 2006). This indicates
that a critical, minimal level of sustained ketosis is neces-
sary but not sufficient to maintain seizure control. Thus,
it would seem that metabolic adaptations to KDs underlie
their key anticonvulsant actions.
Many studies and anecdotal observations have sug-
gested that the KD is most effective in immature animals
or infants and children (Livingston, 1972; Uhlemann and
Neims, 1972; Otani et al., 1984; Bough et al., 1999b; Rho
et al., 1999). This is perhaps dueto enhanced metabolicca-
pacity, more efficient extraction of ketone bodies from the
blood (Morris, 2005), and/or greater compliance of KDsin the pediatric population. However, a lack of efficacy
in older children or adults may simply reflect noncompli-
ance or dietary intolerance rather than an inadequate re-
sponse physiological (Livingston, 1972). The KD has been
demonstrated to be similarly effective in infants (Nordli
et al., 2001; Kossoff et al., 2002), adolescents (Kinsman
et al., 1992; Mady et al., 2003), and adults (Sirven et al.,
1999; Coppola et al., 2002). Furthermore, experimental
KDs are effective in both young (i.e.,
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
4/16
46 K. J. BOUGH AND J. M. RHO
glucose restriction might each lead directly or indirectly
to seizure control. While it is possible that any one of
these KD-induced changes is responsible for the anticon-
vulsant action of the KD, available evidence suggests that
improved seizure control, at a minimum, likely requires
all three.
Role of ketone bodies
Beta-hydroxybutyrate (BHB)is the predominant ketone
body measured in the blood, and as such, has been used as
a clinical measure of KD implementation (Fig. 1). Accord-
ingly, nearly all KD studies have attempted to establish a
causative link between ketonemia and anticonvulsant ef-
ficacy. Although robust elevations in plasma BHB levels
have been observed during KD treatment (Bough et al.,
1999b; Thavendiranathan et al., 2000), there is no signif-
icant correlation between plasma BHB levels and seizure
protection. Optimal seizure protection generally lags days
to weeks behind the development of ketonemia, which oc-
curs within hours of KD onset.
Nevertheless, there is some evidence that ketones other
than BHB may possess anticonvulsant properties. When
injected into animals, acetone and its parent acetoacetate
(ACA), prevent acutely provoked seizures. Seminal work
in the 1930s revealed that acute intraperitoneal admin-
istration of acetone or ethyl-acetoacetate protected rab-
bits from thujone-induced seizures (Helmholz and Keith,
1930; Keith, 1933). Thujone is the active constituent of
wormword oil, and is an antagonist of GABAA receptors
(Hold et al., 2000). More recent experimental studies have
shown similar results in rodents. Acetone (Likhodii et al.,
2003) and ACA (Rho et al., 2002) — but not BHB — wereanticonvulsant in a variety of acute and chronic models of
epilepsy, consistent with earlier observations (Helmholz
FIG. 1. Metabolic pathwayshighlighting the production of ketone bodies fatty acids during fasting or treatment with the ketogenic diet (KD).Estimated fasting- or KD-induced concentrations of beta-hydroxybutyrate, acetoacetate, and acetone in blood are listed (large boxes).Measures of beta-hydroxybutyrate levels in blood are most commonly used as the clinical indicator of successful KD treatment. FromLikhodii and Burnham (2004).
and Keith, 1930; Yamashita et al., 1976; Vodickova et al.,
1995). Clinically, acetone levels of up to 1 millimolar
(mM) were detected in the brains of five of seven well-
controlled epileptic patients following KD using mag-
netic resonance spectroscopic techniques (Seymour et al.,
1999).Althoughacetone could notbe detected in twoother
seizure-free patients, the authors concluded that acetonecontributes to the anticonvulsant effect of the KD. Inter-
estingly, the concept that a lipophilic solvent may potently
block seizure activity is not new. The classic example of
this is valproic acid, which was initially used as a solvent
to dissolve investigational anticonvulsant compounds, but
was serendipitously discovered to possess intrinsic anti-
convulsant properties.
Whereas in vivo pharmacodynamic studies have
suggested that both ACA and acetone may act as
anticonvulsant agents, there is no evidence that ketone
bodies can directly modulate synaptic transmission and/or
neuronal excitability. In vitro cellular electrophysiologi-
cal experiments have failed to demonstrate an effect on the
principal ion channels that mediate neuronal excitability
and inhibition. Specifically, neither L-BHB nor ACA were
found to modulate GABAA receptors, AMPA receptors,
or NMDA receptors in both hippocampus and neocortex
of rats (Thio et al., 2000; Donevan et al., 2003). Despite
these negative observations, it remained possible that ke-
tone bodies might affect network activity or synchrony.
However, in field potential recordings conducted in vitro,
Thio et al. (2000) demonstrated clearly that neither ACA
nor BHB modified evoked excitatory postsynaptic poten-
tials (EPSPs) or population spikes in the CA1 subfield of
the hippocampal tissue. In summary, there is no evidencefor direct anticonvulsant effects for either ACA or BHB,
and acetone has yet to be studied in neuronal (CNS) tissue.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
5/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 47
This may, in large part, reflect the technical difficulties in
investigating a compound that is highly volatile and can
react with perfusion systems ordinarily used in pharma-
cological in vitro experiments.
Recently, it has been suggested that ACA and/or its
metabolic byproduct, acetone, may activate a novel class
of potassium leak channels known as the two-pore do-main or K2P channels (Vamecq et al., 2005). K2P channels
represent a diverse superfamily of channels that generally
hyperpolarize cell membranes,and regulate membrane ex-
citability both pre- and postsynaptically (Lesage, 2003).
These channels can be modulated by changes in pH, os-
molality, temperature, mechanical pressure, and certain
fatty acids (Franksand Honore, 2004).Links between KD-
induced elevations in ketone bodies (and/or fatty acids, as
discussed below) and K2P channels, however, have yet to
be explored.
In conclusion, although ketone bodies have been shown
to possess anticonvulsant properties in vivo, there is no ev-
idence to date that they mediate directly these effects. It
is clear that some degree of sustained ketosis is required
for clinical efficacy and that efficacy is maximized over a
period of weeks versus days, despite a rapid onset of keto-
sis within hours. Whereas it is plausible that some dietary,
pharmacokinetic factor(s) results in some level of seizure
protection, the approximate 2-week time course for opti-
mal seizure protection suggests a pharmacodynamiceffect
of the KD (e.g., parallel time course for changes in gene
expression, mitochondrial proliferation, up-regulation of
UCPs/transporters, etc) likely underlies the anticonvulsant
nature of the diet. Thus, available data suggest that adap-
tations to, rather than a direct effect of, ketosis underliethe anticonvulsant nature of the KD.
Role of glucose restriction
Whereas most studies have suggested that persistent
ketosis is essential to KD-induced seizure protection, oth-
ers have posited that glucose restriction is the key fea-
ture (Greene et al., 2003). In addition to ketosis, it is
clear that as ketonemia develops, another immediate con-
sequence of CR and/or KDs is a ‘moderate’ reduction
in blood glucose. Does caloric restriction simply act to
limit gluconeogenic substrates that would otherwise re-duce KD ratio and counter efficacy? Or, might glucose re-
striction result in another metabolic adaptation that helps
quell aberrant hyperexcitability? Calorie restriction alone
was sufficient to retard seizure susceptibility in juvenile
and adult epileptic EL mice; and, blood glucose lev-
els were inversely correlated with a decreased risk of
seizures (Greene et al., 2001). Greeneet al.(2003) hypoth-
esized that CR reduces energy production through glycol-
ysis, which limits a neuron’s ability to reach (and main-
tain) high levels of synaptic activity necessary for seizure
genesis.
Others have hypothesized that glucose restriction dur-
ing KD treatment activates ATP-sensitive potassium
(KATP) channels (Schwartzkroin, 1999; Vamecq et al.,
2005). Interestingly, KATP channels are ligand-gated re-
ceptors broadly expressed throughout the central nervous
system, in both neurons and glia (Thomzig et al., 2005).
These channels act as metabolic sensors, linking cellular membrane excitability to fluctuating levels of ADP and
ATP. Activation of this receptor by reduced ATP/ADP ra-
tios opens the channel and leads to membrane hyperpo-
larization. When glucose is limited (e.g., during adminis-
tration of a classic KD, which is typically CR by 25%),
KATP channels might open to hyperpolarize the cell as the
intracellular ATP concentrations fall. Conversely, when
glucose is present andATP concentrations rise, KATP chan-
nels close. As such, KATP channels may provide a mea-
sure of protection against a variety of metabolic stressors
such as hypoxia, ischemia, and hypoglycemia, and are
believed to regulate seizure threshold (Seino and Miki,
2003).
KATP channels are particularly abundant in the substan-
tia nigra (Hicks et al., 1994), a region of the brain thought
to act centrally in the propagation of seizure activity
(Iadarola and Gale, 1982). KATP channels would therefore
be ideally positioned to metabolically regulate the onset
of several different seizure types, as does the KD. There is
growing evidence that KATP channels may critically reg-
ulate seizure activity. Genetically engineered mice that
overexpress the sulfonylurea (SUR) subunit of KATP chan-
nels were significantly more resistant to seizures induced
by kainate, and showed no marked cell loss in hippocam-
pus (Hernandez-Sanchez et al., 2001). Studies of KATPchannel ( Kir6.2−/−) knockout mice suggested that these
channels help determine seizure threshold (Yamada et al.,
2001). Following hypoxic challenge (∼5% O2), knock-
out mice exhibited myoclonic – tonic seizure activity, and,
ultimately, death compared to controls who all recovered
without sequelae.
Despite these observations, there is one important
caveat in implicating KATP channels as mediators of a KD-
induced anticonvulsant effect. Other studies have demon-
strated an increase in energy reserves (specifically, ATP)
after KD treatment (DeVivo et al., 1978; Pan et al., 1999).
These data predict that KATP channels would remainclosed, not open, during diet treatment, and would thus
contribute to neuronal/glial cell membrane depolarization.
Nevertheless, several findings are consistent with the no-
tion that KATP channels are selectively activated during
administration of a low-glucose, high-fat KD. First, K ATPchannels are regulated preferentially via glycolytic energy
sources (Dubinskyet al., 1998). It hasrecentlybeen shown
that the glycolytic enzyme glyceraldehyde 3-phosphate
dehydrogenase (GAPDH) serves as an accessory pro-
tein to KATP channels and regulates directly their activity
(Dhar-Chowdhury et al., 2005; Jovanovic et al., 2005).
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
6/16
48 K. J. BOUGH AND J. M. RHO
The observed reduction in glycolytic processes af-
ter KD treatment (specifically, the concentration of
fructose-1,6-bisphosphate, the key regulatory enzyme
of glycolysis) is consistent with this notion (DeVivo
et al., 1978; Puchowicz et al., 2005; Melo et al., 2006).
Glycolytic flux may be further limited as a consequence
of elevated ATP (DeVivo et al., 1978; Otani et al., 1984;Pan et al., 1999; Bough et al., 2006) and citrate (Yudkoff
et al., 2001) levels on KD treatment; both ATP and citrate
are feedback inhibitors of glycolysis.
Second, it is hypothesized that the accumulation of free
fatty acids over thecourse of KD administration (Dekaban,
1966) may boost KATP channel activation (Vamecq et al.,
2005). Whereas PUFAs freely cross the BBB, saturated
free fatty acids are transported across the BBB via carrier-
mediated processes (Avellini et al., 1994). Fatty acids
that intercalate within neuronal cell membranes have been
shown to interact potently with KATP channels, specifically
reducing their affinity for (and inhibition by) ATP (Shyng
and Nichols, 1998). Overall, these findings suggest that
the unique nature of low-glucose, high-fat KDs promotes
KATP channel activation, despite observed enhancements
in oxidative energy production.
Recent experiments involving 2-deoxyglucose (2-DG)
provide further support for a glucose-restriction hypothe-
sis of KD action. Two-deoxyglucoseis a glucose analogue,
which inhibits phosphoglucose isomerase and, hence, gly-
colysis. Stafstrom et al. (2005) reported that the addi-
tion of 1 mM 2-DG decreased epileptiform burst fre-
quency to 25 – 80% of baseline in rat hippocampal slices
exposed to elevated extracellular potassium. More signifi-
cantly, the same group also showedthat 2-DG (250 mg/kg,i.p) elevated the after-discharge threshold in olfactory
bulb of perforant-path kindled rats, markedly reduced the
progression of kindling, and limited the expression of
BDNF and its cognate receptor, trkB (Garriga-Canut et al.,
2006).
Interestingly, there are a number of anticonvulsant par-
allels between 2-DG (Stafstrom et al., 2005; Garriga-
Canut et al., 2006) and KD treatment (Bough et al., 2003).
First, both 2-DG and KD elevated electrographic seizure
threshold in vivo; second, both 2-DG and KD potently re-
tarded the progression of epileptogenesisin kindling mod-
els of epilepsy in vivo; and, third, both 2-DG (in vitro)and KD (in vivo) diminished measures of hippocampal
hyperexcitability. These results collectively suggest that
the anticonvulsant actions of KD may work, in large part,
via an inhibition of glycolysis. Importantly, because 2-DG
is fairly well tolerated when administered orally (Pelicano
et al., 2006), this compound may represent a novel treat-
ment strategy for epilepsy.
Role of fatty acids
Polyunsaturated fatty acids (PUFAs) such as docosa-
hexanoic acid (DHA, C22:6ω3), arachidonic acid (AA,
C20:4ω6), or eicosapentanoic acid (EPA, C20:5ω3) are
believed to affect profoundly cardiovascular function and
health (Leaf and Kang, 1996; Nordoy, 1999; Leaf et al.,
2003).In cardiac myocytes, PUFAs inhibited fast, voltage-
gated sodium channels (Xiao et al., 1998) and L-type cal-
cium channels (Xiao et al., 1997). Similar findings have
been observed in neuronal tissue. For example, DHA andEPA diminished neuronal excitability and bursting in hip-
pocampus (Xiao and Li, 1999).
It is not surprising then that PUFAs are becoming an in-
creasingly popular focus of KD research. After KD treat-
ment, specific PUFAs (i.e., AA and DHA) were found to
be elevated in both serum (Cunnane et al., 2002; Fraser
et al., 2003) and brain (Taha et al., 2005) of patients and
animals. Importantly, one report documented that the rise
(or drop) in total fatty acids during KD treatment closely
paralleled clinical improvement (or loss)of seizure control
(Dekaban, 1966). An additional study found that dietary
supplementation with 5 g of (65%) n-3 PUFAs once per
day produced a marked reduction in seizure frequency
and intensity in a few epileptic patients (Schlanger et al.,
2002). These findings suggest that KD-induced elevations
in PUFAs such as DHA and/or AA might act directly to
limit neuronal excitability and dampen seizure activity.
PUFAs could ultimately block seizure activity in a num-
ber of ways (Fig. 2). First, PUFAs may inhibit directly ion
channel activity. Omega-3 (ω-3) PUFAs have been shown
to: (1) inhibit both voltage-gated Na+ and Ca2+ channels,
(2) increase the resistance to bursting induced by bicu-
culline, zero Mg2+, pentylenetetrazole or glutamate, and
(3) prolong the recovery time from inactivation in hip-
pocampal neurons (Vreugdenhil et al., 1996; Xiao and Li,1999; Young et al., 2000). Second, in conjunction with ke-
tone bodies, PUFAs may activate a lipid-sensitive class of
K2P potassium channels (Vamecq et al., 2005). And, third,
PUFAs may enhance the activity of the Na+ /K+-ATPase
(sodium pump). Elevated ω-3 and diminished ω-6 PU-
FAs levels in plasma membranes significantly increased
sodium pump function (Wu et al., 2004). These findings
indicate that elevations in brain levels of PUFAs after KD
treatment (Taha et al., 2005) could help reduce neuronal
hyperexcitability via a variety of direct mechanisms.
Uncoupling proteins
In addition to their direct actions on neuronal ex-
citability, PUFAs may also act indirectly to limit ex-
citotoxicity and neurodegeneration. PUFAs regulate the
expression of numerous genes in brain via transcription
factors such as PPARα (peroxisome proliferator-activated
receptor-α; Sampath and Ntambi, 2004). Through in-
duction of PPARα and its coactivator PGC-1, PUFAs
induce the expression of mitochondrial uncoupling pro-
teins (UCPs) and activate these proteins directly as well
(Jaburek et al., 1999; Diano et al., 2003). Recent evidence
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
7/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 49
FIG. 2. Potential pathways through which polyunsaturated fatty acids (PUFAs) may limit hyperexcitability in the brain. Acting directly,PUFAs such as arachidonic acid (AA), docosahexanoic acid (DHA), and/or eicosapentanoic acid (EPA) might inhibit both voltage-gatedNa+ and Ca2+ channels, activate a lipid-sensitive class of K2P potassium channels, and enhance the activity of the Na
+ /K+-ATPase tolimit neuronal excitability and dampen seizure activity. Acting indirectly, PUFAs might induce the expression and activity of uncouplingproteins (UCPs) to diminish reactive oxygen species (ROS), reduce neuronal dysfunction and induce a neuroprotective effect. Finally,PUFAs are expected to activate PPARα and induce a coordinate up-regulation of energy transcripts leading to enhanced energy reserves,stabilized synaptic function and limited hyperexcitability.
suggests that PUFAs are required for mitochondrial UCP
activity (Garlid et al., 2001).
Uncoupling proteins are homodimers that span the in-
ner mitochondrial membrane and allow a proton leak fromthe intermembrane space to the mitochondrial matrix.
There are three major isoforms that have been identified
in the brain, UCP2, UCP4 and UCP5 (a.k.a., BMCP-1
or brain mitochondrial carrier protein-1). UCP proteins
are increasingly implicated in the regulation of neuronal
excitability and survival (Andrews et al., 2005). The un-
coupling effect, albeit of small magnitude, reduces the
proton-motive force, disassociates or ‘uncouples’ elec-
tron transport from ATP production, and indirectly de-
creases the production of reactive oxygen species (ROS).
Although it would seem that increased levels of UCP pro-
teins would diminish cellular energy production, Diano
et al. (2003) showed that chronic overexpression of UCP2
in neuronal tissue increased cellular ATP and ADP levels
by triggering mitochondrial biogenesis. KD appears to do
the same; that is, studies show that the KD induces UCP
expression, stimulates mitochondrial biogenesis, and en-
hances energy production (see also below). Seizures, by
comparison, increase ROS generation and/or mitochon-
drial dysfunction, which can lead to neuronal dysfunction
and excitotoxicity (Layton and Pazdernik, 1999; Kovacs
et al., 2001; Kovacs et al., 2002; Sullivan et al., 2003).
Interestingly, UCP2 is up-regulated after seizures (Diano
et al., 2003). The protective role of UCPs was recently
highlighted by Sullivan et al. (2003) who demonstrated
that dietary enhancement of UCP expression and function
in immature rats protected against kainate-induced exci-totoxicity, most likely by decreasing ROS generation (An-
drews et al., 2005). Further work demonstrated that mice
maintained on a high-fat KD demonstrated an increase in
the hippocampal expression and activity of all three mi-
tochondrial UCPs and exhibited a significant reduction in
ROS generation in mitochondria isolated from the same
brain region (Sullivan et al., 2004). In conjunction with
reports that ketone bodies potently decrease ROS gen-
eration (Veech et al., 2001; Veech, 2004), these reports
suggest that the KD compensates for seizure-induced el-
evations in ROS generation and neuronal dysfunction to
provide a neuroprotective effect.
Energy production
Polyunsaturated fatty acids additionally regulate the
transcription of numerous genes linked to energy
metabolism (Sampath and Ntambi, 2005) through activa-
tion of PPARα, a scenario inwhich the KDis thought to re-
program cellular metabolism (Cullingford, 2004). Indeed,
numerous studies have described changes consistent with
an enhancement in energy production following KD treat-
ment. First, microarray expression studies demonstrated
that KD induces a coordinated up-regulation of several
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
8/16
50 K. J. BOUGH AND J. M. RHO
dozenmetabolic genesassociated with oxidative phospho-
rylation after KD (Noh et al., 2004; Bough et al., 2006).
Second, KD treatment stimulated mitochondrial biogene-
sis, resulting in a striking 46% increase in the number of
mitochondria in the hilar/dentate gyrus region of rat hip-
pocampus (Bough et al., 2006). And, third, levels of en-
ergy metabolites were increased after KD. Brain glycogenand ATP concentrations were boosted throughout rodent
brain (DeVivo et al., 1978; Otani et al., 1984) andtherewas
an elevation in the phosphocreatine-to-creatine (PCr:Cr)
energy-reserve ratio in both animals (Bough et al., 2006)
and humans (Pan et al., 1999). These findings are consis-
tent with results that show ketones (4 mM BHB + 1 mM
ACA) increased hydraulic work by 14% and improved
energy status in perfused heart tissue (Sato et al., 1995).
Further, there is an overall increased metabolic efficiency
(DeVivo et al., 1978; Bough et al., 2006), decreased res-
piratory quotient (Bough et al., 2000b), and maximal mi-
tochondrial respiratory rate in rodents following the KD
(Sullivan et al., 2004). Collectively, these data provide
compelling evidence that the KD enhances oxidative en-
ergy production by activating a variety of transcriptional,
translational, and biochemical mechanisms in a concerted
fashion.
Metabolic dysfunction has been identified in regions of
hyperexcitability within the brain and is associated with
several epileptic conditions. Impairment of mitochondrial
function has been observed in the seizure foci of both hu-
man and experimental epilepsies (Kunz et al., 2000). Se-
vere metabolic dysfunction occurred in both human and
rat hippocampal tissue during periods of heightened neu-
ronal activity (Kann et al., 2005). Kudin et al. (2002)demonstrated that seizure activity down-regulated mito-
chondrial enzymes involved in oxidative phosphorylation.
In an earlier study, the same group demonstrated a specific
deficiency in complex I activity and mitochondrial ultra-
structural abnormalities within the hippocampal CA3 re-
gion of epileptic tissue resected from 57 human patients
(Kunz et al., 2000). In view of previous studies demon-
strating impaired oxidative phosphorylation capacity in
pilocarpine-treated rats (Kudin et al., 2002) and in patients
with epilepsy (Antozzi et al., 1995; Kunz et al., 2000), a
KD-induced augmentation in oxidative phosphorylation
and energy reserves seems likely to counter energetic de-ficiencies in epileptic tissue, making neuronal tissue more
resilient to aberrant neuronal activity and, in this way, con-
tributing to the diet’s anticonvulsant actions.
Stabilized synaptic function
Intriguing as this argument may be, how exactly would
enhanced energy reserves lead to stabilized synaptic func-
tion and diminished seizures? One possibility is via the
sodium pump. ATP is primarily used to maintain ionic gra-
dients, especially through actions of the transmembrane
sodium pump (Hulbert and Else, 2000). Schwartzkroin
originally hypothesized that KD-induced elevations in
ATP concentrations might enhance and/or prolong the ac-
tivation of theNa+ /K+-ATPase , perhaps via an increase in
the delta-G
of ATP hydrolysis (Veech et al., 2001; Veech,
2004). In neurons, increased sodium pump activity might
hyperpolarize the cell and/or reduce the resting mem-
brane potential to diminish firing probability. EnhancedNa+ /K+-ATPase function in neurons might also preserve
normal neuronal functioning and/or delay a pathological
buildup of high external K+ (Xiong and Stringer, 2000).
In glia, increased activation of the Na+ /K+-ATPase might
slow glial depolarization and allow for prolonged uptake
of extracellular K+ during periods of intense neuronal ac-
tivity (e.g., high-frequency bursting). Increases in neu-
ronal and/or glial action of the sodium pump would be
expected to limit hyperexcitability and increase the resis-
tance to seizures, as is noted after treatment with KD.
Although no studies have tested this sodium-pump
hypothesis directly, a recent report suggests that KD
tissue is more resistant to metabolic stress. When chal-
lenged with mild hypoglycemia, synaptic transmission
within the dentate gyrus was maintained for approxi-
mately 60% longer in tissue from KD-fed animals com-
pared to controls (Bough et al., 2006). These data suggest
that the KD stabilizes synaptic transmission (both excita-
tory and inhibitory) for prolonged periods of time during
metabolic stress such as during seizure activity. Hence,
it seems likely that the KD induces seizure protection
in part by preventing neuronal dysfunction (diminution
of ROS/enhancement of energy reserves) and stabilizing
synaptic transmission (enhancement in energy reserves).
A role for neurotransmitter systems
The noradrenergic hypothesis
One of the more intriguing observations regarding KD
action involves norepinephrine, its receptors and signaling
cascades. In general, increases in noradrenergic tone re-
sult in an anticonvulsant effect. Several lines of evidence
support this view. Norepinephrine (NE) re-uptake in-
hibitors can prevent seizure activity in genetically epilepsy
prone rats (GEPRs; Yan et al., 1993) and pharmacolog-
ical NE agonists are generally, though not always, an-
ticonvulsant (Weinshenker and Szot, 2002); damage tothe locus coeruleus — the principal region of the brain
from which ascending and descending noradrenergic in-
nervation originates — converts occasional seizures into
self-sustaining status epilepticus (SSSE) in rats (Giorgi
et al., 2004); animals are more prone to seizures when NE
is chemically depleted with reserpine (Weinshenker and
Szot, 2002); and, interestingly, there are several reports of
diminished brain levels of NE in several animal models
of epilepsy, including GEPRs, kindled animals, EL mice,
seizure-sensitive Mongolian gerbils, and tottering mice
(Weinshenker and Szot, 2002).
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
9/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 51
Of significant interest is the observation that mice lack-
ing the ability to produce NE ( Dbh−/− knockout mice)
do not exhibit an increased resistance to flurothyl seizures
when treated with a KD (Szot et al., 2001). These data
indicate that NE is required for the anticonvulsant effect
of KD, at least in the flurothyl seizure threshold model.
Weinshenker and Szot (2002) additionally reported an ap-proximate twofold increase in NE levels in hippocampus
following a KD, suggesting that KD increases basal re-
lease of NE. These studies indicate the anticonvulsant ac-
tion of KD may result in part from an enhancement in
noradrenergic signaling in the brain.
If the KD enhances NE release as described above, it
may also promote the corelease of anticonvulsant orexi-
genicpeptides such as neuropeptide-Y (NPY)and galanin.
NPY has been shown to inhibit glutamatergic synaptic
transmission and epileptogenesis in vitro (Rhim et al.,
1997; Richichi et al., 2004; Vezzani and Sperk, 2004);
galanin has been shown to limit SSSE (Saar et al., 2002)
and diminish both excitatory synaptic transmission and
ictal activity in vitro (Schlifke et al., 2006). Both neu-
ropeptides are elevated after calorie restriction. However,
there was no evidence for enhanced transcription of either
of these peptides in the brain after KD treatment, suggest-
ing that neither NPY nor galanin contribute significantly
to the anticonvulsant actions of KD (Tabb et al., 2004).
The GABAergic hypothesis
One of the more popular hypotheses for KD action in-
volves γ -aminobutyric acid (GABA), the major inhibitory
neurotransmitter in the mammalian brain. In general, the
KD is most effective against seizures evoked by GABAer-gic antagonists. The KD potently inhibits seizures in-
FIG. 3. Metabolic modifications of glutamate and GABA synthesis as a consequence of diminished glucose and ketosis. In ketosis, beta-hydroxybutyrate and acetoacetate contribute heavily to brain energy needs. A variable fraction of pyruvate (1) is ordinarily converted toacetyl-CoA via pyruvate dehydrogenase. In contrast, all ketone bodies generate acetyl-CoA, which enters the tricarboxcylic acid (TCA)cycle via the citrate synthetase pathway (2). This involves the consumption of oxaloacetate, which is necessary for the transamination ofglutamate to aspartate. Oxaloacetate is then less available as a reactant of the aspartate aminotransferase pathway, which couples theglutamate-aspartate interchange via transamination to the metabolism of glucose through the TCA cycle. Less glutamate is convertedto aspartate and thus, more glutamate is available for synthesis of GABA (3) through glutamic acid decarboxylase (GAD). Adapted fromYudkoff et al. (2004).
duced by pentylenetetrazole, bicuculline, picrotoxin, and
γ -butyrolactone. In contrast, the diet demonstrates lit-
tle if any efficacy in acute seizure models involving ac-
tivation of ionotropic glutamate receptors (e.g., kainic
acid), voltage-dependent sodium channels (e.g., maximal
electroshock [MES]), or glycine receptor inhibition (e.g.,
strychnine; Bough et al., 2002).Yudkoff et al. (2005) have proposed that ketosis in-
duces major shifts in brain amino acid handling favoring
the production of GABA. This results from a reduction
of aspartate relative to glutamate, the precursor to GABA
synthesis, and a shift in the equilibrium of the aspartate
aminotransferase reaction in the ketotic state. As a re-
sult, there is an increase in glutamic acid decarboxylase
(GAD) activity and GABA production (Fig. 3). Elevated
GABA levels would,in turn, be expectedto dampenhyper-
excitability throughout the brain. Several studies support
this possibility. First, KD and CR diet treatments both
increased GAD transcript and protein levels in inferior
and superior colliculi, cerebellar and temporal cortex, and
striatum (the latter, KD only; Cheng et al., 2004). Sec-
ond, both BHB and ACA increased the rate and extent
of GABA formation in synaptosomes (Erecinska et al.,
1996; Yudkoff et al., 1997). And, finally, KD treatment
in vivo modified amino acid levels in a manner consistent
with enhanced GABA production (Yudkoff et al., 2001;
Melo et al., 2006). Although brain levels of glutamate
and GABA have not been consistently elevated in rodents
(DeVivo et al., 1978; Al-Mudallal et al., 1996; Yudkoff
et al., 2001; Bough et al., 2006), two recent clinical stud-
ies report significant increases in GABA levels following
KD treatment (Wang et al., 2003; Dahlin et al., 2005),further substantiating this view.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
10/16
52 K. J. BOUGH AND J. M. RHO
In addition to biochemical measures of KD-enhanced
GABAergic inhibition, there is functional evidence as
well. Electrophysiological recordings conducted in vivo
demonstrated that network excitability was diminished in
both KD- and calorie-restricted rats (Bough et al., 2003);
greater stimulus intensities were required to evoke popu-
lation spikesin both CR-and KD-fed animals compared toad libitum controls. Paired-pulse inhibition was increased.
Both CR and KD dietary treatments resulted in greater
paired-pulse inhibition compared to controls at the 30-
ms interpulse interval (Bough et al., 2003), a result con-
sistent with an enhancement in fast, GABAA-mediated
inhibition. Additionally, KD-fed animals exhibited an el-
evated electrographic seizure threshold and an increased
resistance to a modified, 1-day kindling protocol (max-
imal dentate activation). These data suggested that both
KD and calorie-restricted diets limited network excitabil-
ity and elevated seizure threshold via an enhancement of
GABAergic inhibition.
GABAergic interneurons, which at baseline have more
depolarized resting membrane potentials, endure non-
accommodating bursts of neuronal firing and must
metabolically persist (Attwell and Laughlin, 2001), lest
network inhibition becomes compromised. Previous stud-
ies have shown that a KD increases total brain [ATP]
(DeVivo et al., 1978) and PCr/Cr or PCr/ATP energy re-
serve (Pan et al., 1999; Bough et al., 2006). Accordingly,
KD-induced elevations in PCr are likely to play a pivotal
role in maintaining the activity of the Na+ /K+-ATPase
during periods of intense seizure activity, in both gluta-
matergic and GABAergic neurons. In a recent study of
human temporal lobe epilepsy (Williamson et al., 2005),the PCr/ATP ratio correlated with the recovery of the
membrane potential following a stimulus train, which
was inversely correlated with granule cell bursting. Be-
cause creatine kinase is predominantly localized within
GABAergic interneurons (Boero et al., 2003), Boero et al.
concluded that PCr and energy levels are especially crit-
ical to the maintenance of GABAergic inhibitory output.
In this manner, a KD-induced increase in energy reserves
might enhance GABAergic function in particular and im-
prove seizure control.
HOW CAN THE KETOGENICDIET BE OPTIMIZED?
Historically, few guidelines have emerged regarding the
clinical implementation of the KD and its variants – in-
cluding the medium-chain triglyceride (MCT) formula-
tion (Huttenlocher et al., 1971) and more recent options
such as the Atkins diet (Kossoff et al., 2003; Kossoff
et al., 2006). This is largely a result of the fact that, until re-
cently, few KD centers existed throughout the world. Even
with a resurgence of interest in dietary approaches toward
epilepsy treatment in the past decade, there remains a no-
table absence of Class I and II clinical studies. Today, few
question the clinical efficacy of the KD in both young and
older patients (Vining, 1999; Coppola et al., 2002; Mady
et al., 2003), and many successful international centers
have evolved (Kossoff and McGrogan, 2005; Freeman
et al., 2006). However, since we do not fundamentally
know how the KD prevents seizures, there exists as yet norational basis for optimizing the efficacy of the diet, other
than through trial and error.
When examining the accumulated clinical data, it ap-
pears seizure control can be achieved in the majority
of epileptic patients as long as there is a shift from
glycolytic flux to intermediary metabolism (resulting in
measurable ketosis), irrespective of the precise dietary
formulation (Henderson et al., 2006). On the other hand,
the experimental literature suggests that different treat-
ment protocols may result in differential efficacy or even
lack of efficacy, despite significant ketosis (Bough et al.,
2000a; Thavendiranathan et al., 2000; Bough et al., 2002;
Thavendiranathan et al., 2003). Most of the published
studies have been based on acute seizure models, and not
on developmental epilepsy models. Hence, of course, one
must bear in mind that, despite dozens of animal models
of the KD, none recapitulate all of the essential features
in the human epileptic condition (Stafstrom, 1999).
So how can we reach the goal of developing a safer and
more effective KD? The reductionist approach posits that
were we to identify the critical mediator of the diet’s an-
ticonvulsant effect, administration of this substrate alone
would likely yield a similar clinical effect as the tradi-
tional KD, and importantly, spare the patient significant
side-effects that may preclude its use — even in the face of clear clinical efficacy. The closest we have come to this
situation is the recent use of BHB as an oral neuroprotec-
tant. Promising results have already been demonstrated
in Phase I clinical trials (Smith et al., 2005). Neverthe-
less, despite increasing experimental evidence that BHB
and ACA both possess neuroprotective properties (Kashi-
waya et al., 2000; Noh et al., 2006), a direct anticonvulsant
effect of ketone bodies has not yet been demonstrated in
epileptic brain, either animal or human. Intriguing, how-
ever, are animal studies indicating that ACA and acetone
are anticonvulsant in acute seizure models. Yet, there re-
mains a perplexing lack of an acute anticonvulsant effectof the principal ketone body, BHB.
Conversely, if we believe that certain PUFAs, in lieu of
ketone bodies, are direct mediators of an anticonvulsant ef-
fect (Cunnane et al., 2002; Cunnane, 2004), as suggested
by clinical studies (Schlanger et al., 2002; Fraser et al.,
2003; Fuehrlein et al., 2004; Yuen et al., 2005), we may be
closer to distilling the essence of the KD. However, there
is likely no single fatty acid that is necessary and sufficient
for an anticonvulsant effect. And experimentally, while it
has been straightforward to demonstrate the inhibitory ef-
fects of PUFAs on specific voltage-gated ion channels and
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
11/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 53
FIG. 4. Hypothetical pathways leading to the anticonvulsant effects of the ketogenic diet (KD). Elevated free fatty acids (FFA) lead tochronic ketosis and increased concentrations of polyunsaturated fatty acids (PUFAs) in the brain. Chronic ketosis is predicted to leadto increased levels of acetone; this might activate K2P channels to hyperpolarize neurons and limit neuronal excitability. Chronic ketosisis also anticipated to modify the tricarboxcylic acid (TCA) cycle. This would increase glutamate and, subsequently, GABA synthesis inbrain. Among several direct inhibitory actions (see also Fig. 2), PUFAs boost the activity of brain-speci fic uncoupling proteins (UCPs).This is expected to limit ROS generation, neuronal dysfunction, and resultant neurodegeneration. Acting via the nuclear transcriptionfactor peroxisome proliferator-activated receptor-α (PPARα), PUFAs would induce the expression of UCPs and coordinately up-regulateseveral dozen genes related to oxidative energy metabolism. PPARα expression is inversely correlated with IL-1β cytokine expression;given the role of IL-1β in hyperexcitability and seizure generation (Vezzani et al., 2000), diminished expression of IL-β cytokines during KDtreatment could lead to improved seizure control. Ultimately, PUFAs would stimulate mitochondrial biogenesis. Mitochondrial biogenesis ispredicted to increase ATP production capacity and enhance energy reserves, leading to stabilized synaptic function and improved seizurecontrol. In particular, an elevated phosphocreatine:creatine (PCr:Cr) energy-reserve ratio is predicted to enhance GABAergic output,
perhaps in conjunction with the ketosis-induced elevated GABA production, leading to diminished hyperexcitability. Reduced glucosecoupled with elevated free fatty acids are proposed to reduce glycolytic flux during KD, which would further be feedback inhibited by highconcentrations of citrate and ATP produced during KD treatment. This would activate metabolic KATP channels. Opening of KATP channelswould hyperpolarize neurons and diminish neuronal excitability to contribute to the anticonvulsant (and perhaps neuroprotective) actionof the KD. Reduced glucose is also expected to downregulate brain-derived neurotrophic factor (BDNF) and trkB signaling in brain. Asactivation of TrkB pathways by BDNF have been shown to promote hyperexcitability and kindling, these potential KD-induced effects wouldbe expected to limit the symptom (seizures) as well as the progression of epilepsy. Boxed variables depict findings taken from KD studies;up (↑) or down (↓) arrows indicate the direction of the relationship between variables as a result of KD treatment.
the resultant diminution of cellular excitability in vitro,
it is not an easy task to demonstrate that ingestion of a
specific fatty acid or fatty acid cocktail, acts directly on
relevant brain receptor targets without first undergoing
beta-oxidation. The collective data, from both animals and
humans, indicate that the critical condition necessary for
achieving seizure control is a metabolic shift toward fatty
acid oxidation from glycolysis, reflected in the variable
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
12/16
54 K. J. BOUGH AND J. M. RHO
rise in blood/brain ketone levels and a concomitant (mod-
erate) reduction in blood/brain glucose. Fatty acid compo-
sition may not ultimately matter, as long as this important
metabolic shift occurs. And, interestingly, calorie restric-
tion (Greene et al., 2001; Bough et al., 2003; Eagles et al.,
2003; Greene et al., 2003) or intake of 2-DG (Stafstrom
et al., 2005), both of which result in mild hypoglycemia,may be the only requirement for seizure protection, re-
gardless of whether fats are consumed or not.
As we continue to explore putative anticonvulsant
mechanisms of KD action, we are left with many out-
standing clinical questions regarding dietary treatments
for epilepsy. Well-designed, multicenter prospective- and
controlled clinical trials are essential toward developing
the optimum KD. If woven together with pharmacokinetic
and pharmacogenetic investigations, these clinical stud-
ies will not only provide further insights into mechanistic
underpinnings, but will also help differentiate responders
from non-responders and identify patients in whom the
diet is definitively contraindicated. Clinicians would be
given the tools to make evidence-based decisions rather
than rely upon a few case – controlled studies, anecdotal re-
ports of efficacy, or clinical folklore as has been the prac-
tice in the past. Toward this end, information regarding the
impact of pharmacogenetics on epilepsy treatment is now
beginning to emerge (Depondt and Shorvon, 2006; Spurr,
2006), although much less is known regarding the genet-
ically determined variables influencing dietary impact on
brain function, particularly as it relates to the epileptic
brain.
CONCLUSIONS
After nearly a century of clinical use, we still do not
know how the KD works. However, much progress in KD
research has been made in the past decade. Among other
factors, current evidence indicates KD optimizes cellular
metabolism. Endogenous biochemical and genetic ‘pro-
grams’ are switched on in the brain in response to keto-
sis, glucose restriction, and elevated free fatty acids. This
unique metabolic state, if maintained, induces a shift away
from glycolytic energy production (glucose restriction)
toward the production of energy via oxidative phospho-
rylation (beta-oxidation of fatty acids and production of ketone bodies). The reduction in glycolytic energy sup-
ply may activate selectively KATP channels to increase the
resistance to onset of ictal activity. An increase in oxida-
tive phosphorylation coupled with an induction of UCPs
and mitochondrial biogenesis can diminish ROS genera-
tion and increase energy reserves, both of which would
be expected to prevent neuronal dysfunction, seizures and
even neurodegeneration.
It is improbable that one mechanistic target or medi-
ator will produce entirely the seizure protection associ-
ated with the KD. Rather, several factors likely contribute
mechanistically to this broadly efficacious treatment for
epilepsy. The challenge of finding key variables is made
ever more difficultby the intrinsic complexity of metabolic
effects and their resultant actions on neurons, glia and on
the epileptic condition itself. We have reviewed here a
number of seemingly disparate variables that must be sus-
tained for a meaningful anticonvulsant effect to be ren-dered. These interrelationships are summarized in Fig. 4.
The fact that a fundamental modification in diet can have
such profound, therapeutic effects on neurological disease
underscores the importance of elucidating mechanisms of
KD action. Future studies will no doubt provide unique
insights into how diet can affect the brain, both in health
and disease, and likely provide the scientific basis for the
development of potent new treatment strategies for the
epilepsies.
REFERENCES
Al-Mudallal AS, LaManna JC, Lust WD, Harik SI. (1996) Diet-inducedketosis does not cause cerebral acidosis. Epilepsia 37:258 – 261.
Andrews ZB, Diano S, Horvath TL. (2005) Mitochondrial uncouplingproteins in the cns: in support of function and survival. Nature Re-views Neuroscience 6:829 – 840.
Antozzi C, Franceschetti S, Filippini G, Barbiroli B, Savoiardo M, Fi-acchino F, Rimoldi M, Lodi R, Zaniol P, Zeviani M. (1995) Epilepsiapartialis continua associated with nadh-coenzyme q reductase defi-ciency. Journal of the Neurological Sciences 129:152 – 161.
Appleton DB, DeVivo DC. (1974) An animal model for the ketogenicdiet. Epilepsia 15:211 – 227.
Attwell D, Laughlin SB. (2001) An energy budget for signaling inthe grey matter of the brain. Journal of Cerebral Blood Flow and Metabolism 21:1133 – 1145.
Avellini L, Terracina L, Gaiti A. (1994) Linoleic acid passage throughthe blood-brain barrier and a possible effect of age. Neurochemical
Research 19:129 – 133.Boero J, Qin W, Cheng J, Woolsey TA, Strauss AW, Khuchua Z. (2003)
Restricted neuronal expression of ubiquitous mitochondrial creatinekinase: changing patterns in developmentand withincreasedactivity. Molecular and Cellular Biochemistry 244:69 – 76.
Bough KJ, Chen RS, Eagles DA. (1999a) Path analysis shows thatincreasing ketogenic ratio, but not beta-hydroxybutarate, elevatesseizure threshold in the rat. Developmental Neuroscience 21:400 – 406.
Bough KJ, Eagles DA. (1999) A ketogenic diet increases the resistanceto pentylenetetrazole-induced seizures in the rat. Epilepsia 40:138 – 143.
Bough KJ, Valiyil R, Han FT, Eagles DA. (1999b) Seizure resistance
is dependent upon age and calorie restriction in rats fed a ketogenicdiet. Epilepsy Research 35:21 – 28.
Bough KJ, Matthews PJ, Eagles DA. (2000a) A ketogenic diet hasdifferent effects upon seizures induced by maximal electroshock
and by pentylenetetrazole infusion. Epilepsy Research 38:105 – 114.
Bough KJ, Yao SG, Eagles DA. (2000b) Higher ketogenic diet ratiosconfer protection from seizures without neurotoxicity. Epilepsy Re-search 38:15 – 25.
Bough KJ, Gudi K, Han FT, Rathod AH, Eagles DA. (2002) An anti-convulsant profile of the ketogenic diet in the rat. Epilepsy Research50:313 – 325.
Bough KJ, Schwartzkroin PA, Rho JM. (2003) Calorie restriction and
ketogenic diet diminish neuronal excitability in rat dentate gyrus invivo. Epilepsia 44:752 – 760.
Bough KJ,Wetherington J, HasselB, Pare JF,GawrylukJW, Greene JG,Shaw R, Smith Y, Geiger JD, Dingledine RJ. (2006) Mitochondrialbiogenesis in the anticonvulsant mechanism of the ketogenic diet. Annals of Neurology 60:223 – 235.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
13/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 55
Cheng CM, Hicks K, Wang J, Eagles DA, Bondy CA. (2004) Caloricrestriction augments brain glutamic acid decarboxylase-65 and -67expression. Journal of Neuroscience Research 77:270 – 276.
Coppola G, Veggiotti P, Cusmai R, Bertoli S, Cardinali S, Dionisi-ViciC, Elia M, Lispi ML, Sarnelli C, Tagliabue A, Toraldo C, Pascotto A.(2002) The ketogenic diet in children, adolescents and young adultswith refractory epilepsy: an italian multicentric experience. Epilepsy Research 48:221 – 227.
Cullingford TE. (2004) The ketogenic diet; fatty acids, fatty acid-activated receptors and neurological disorders. Prostaglandins Leukot Essent Fatty Acids 70:253 – 264.
Cunnane SC, Musa K, Ryan MA, Whiting S, Fraser DD. (2002) Poten-tial role of polyunsaturates in seizure protection achieved with theketogenic diet. Prostaglandins Leukot Essent Fatty Acids 67:131 – 135.
Cunnane SC. (2004) Metabolism of polyunsaturated fatty acids and ke-togenesis: an emerging connection. Prostaglandins Leukot Essent Fatty Acids 70:237 – 241.
Dahlin M, Elfving A, Ungerstedt U, Amark P. (2005) The ketogenicdiet influences the levels of excitatory and inhibitory amino acids
in the csf in children with refractory epilepsy. Epilepsy Research64:115 – 125.
Dekaban AS. (1966) Plasma lipids in epileptic children treated with thehigh fat diet. Archives of Neurology 15:177 – 184.
Dell CA, Likhodii SS, Musa K, Ryan MA, Burnham WM, CunnaneSC. (2001) Lipid and fatty acid profiles in rats consuming differenthigh-fat ketogenic diets. Lipids 36:373 – 378.
Depondt C, Shorvon SD. (2006) Genetic association studies in epilepsypharmacogenomics: lessons learnt and potential applications. Phar-macogenomics 7:731 – 745.
DeVivo DC, Leckie MP, Ferrendelli JS, McDougal DB Jr. (1978)Chronic ketosis and cerebral metabolism. Annals of Neurology3:331 – 337.
Dhar-Chowdhury P, Harrell MD, Han SY, Jankowska D, Parachuru L,Morrissey A, Srivastava S, Liu W, Malester B, Yoshida H, CoetzeeWA. (2005) The glycolytic enzymes, glyceraldehyde-3-phosphatedehydrogenase, triose-phosphate isomerase, and pyruvate kinase arecomponents of the k(atp) channel macromolecular complex and reg-ulate its function. The Journal of Biological Chemistry 280:38464 – 38470.
Diano S, Matthews RT, Patrylo P, Yang L, Beal MF, Barnstable CJ,
Horvath TL. (2003) Uncoupling protein 2 prevents neuronal deathincluding that occurring during seizures: a mechanism for precondi-tioning. Endocrinology 144:5014 – 5021.
Donevan SD, White HS, Anderson GD, Rho JM. (2003) Voltage-dependent block of N-methyl-D-aspartate receptors by the novel an-
ticonvulsant dibenzylamine, a bioactive constituent of l-(+)-beta-hydroxybutyrate. Epilepsia 44:1274 – 1279.
Dubinsky WP, Mayorga-Wark O, Schultz SG. (1998) Colocalization of glycolytic enzyme activity and katp channels in basolateral mem-brane of necturus enterocytes. The American Journal of Physiology275:C1653 – 1659.
Eagles DA, Boyd SJ, Kotak A, Allan F. (2003) Calorie restriction of ahigh-carbohydrate diet elevates the threshold of ptz-induced seizuresto valuesequalto those seen with a ketogenicdiet. Epilepsy Research54:41 – 52.
Erecinska M, Nelson D, Daikhin Y, Yudkoff M. (1996) Regulation of gaba level in rat brain synaptosomes: fluxes through enzymes of the
gaba shunt and effects of glutamate, calcium, and ketone bodies. Journal of Neurochemistry 67:2325 – 2334.
Franks NP, Honore E. (2004) The trek k2p channels and their role ingeneral anaesthesiaand neuroprotection. Trends in PharmacologicalSciences 25:601 – 608.
Fraser DD, Whiting S, Andrew RD, Macdonald EA, Musa-Veloso K,Cunnane SC. (2003) Elevated polyunsaturated fatty acids in bloodserum obtained from children on the ketogenic diet. Neurology60:1026 – 1029.
Freeman J, Veggiotti P, Lanzi G, Tagliabue A, Perucca E. (2006) Theke-togenic diet:from molecular mechanismsto clinical effects. Epilepsy Research 68:145 – 180.
Freeman JM,ViningEP,Pillas DJ,Pyzik PL,Casey JC,KellyLM. (1998)The efficacy of the ketogenic diet-1998: a prospective evaluation of
intervention in 150 children. Pediatrics 102:1358 – 1363.
Freeman JM, Vining EP. (1999) Seizures decrease rapidly after fasting:preliminary studies of the ketogenic diet. Archives of Pediatrics & Adolescent Medicine 153:946 – 949.
Freeman JM, Kelley MT, Freeman JB. (2000) The ketogenic diet: atreatment for epilepsy, 3rd ed. Demos, New York.
Fuehrlein BS, Rutenberg MS, Silver JN, Warren MW, TheriaqueDW, Duncan GE, Stacpoole PW, Brantly ML. (2004) Differentialmetabolic effects of saturated versus polyunsaturated fats in keto-
genic diets. The Journal of Clinical Endocrinology and Metabolism89:1641 – 1645.
GarlidKD, Jaburek M,JezekP. (2001)Mechanism ofuncoupling proteinaction. Biochemical Society Transactions 29:803 – 806.
Garriga-CanutM, SchoenikeB, QaziR, BergendahlK, DaleyTJ, Pfender RM, Morrison JF, Ockuly J, Stafstrom CE, Sutula T, Roopra A.(2006)2-deoxy-d-glucosereducesepilepsyprogressionby nrsf-ctbp-dependent metabaolic regulationof chromatin structure. Nature Neu-roscience 9:1382 – 1387.
Giorgi FS, Pizzanelli C, Biagioni F, Murri L, Fornai F. (2004) The roleof norepinephrine in epilepsy: from the bench to the bedside. Neu-roscience and Biobehavioral Reviews 28:507 – 524.
Greene AE, Todorova MT, McGowan R, Seyfried TN. (2001) Caloricrestriction inhibits seizure susceptibility in epileptic el mice by re-ducing blood glucose. Epilepsia 42:1371 – 1378.
Greene AE, Todorova MT, Seyfried TN. (2003) Perspectives on themetabolic management of epilepsy through dietary reduction of glu-cose and elevation of ketone bodies. Journal of Neurochemistry86:529 – 537.
Helmholz HF, Keith HM. (1930) Eight years’ experience with the ke-togenic diet in the treatment of epilepsy. Journal of the American Medical Association 95:707 – 709.
Henderson CB, Filloux FM, Alder SC, Lyon JL, Caplin DA. (2006)Efficacy of the ketogenic diet as a treatment option for epilepsy:meta-analysis. Journal of Child Neurology 21:193 – 198.
Hernandez-Sanchez C, Basile AS, Fedorova I, Arima H, StannardB, Fernandez AM, Ito Y, LeRoith D. (2001) Mice transgenicallyoverexpressing sulfonylurea receptor 1 in forebrain resist seizureinduction and excitotoxic neuron death. Proceedings of the Na-tional Academy of Sciences of the United States of America 98:3549 – 3554.
Hicks GA, Hudson AL, Henderson G. (1994) Localization of high affin-ity [3H]glibenclamide binding sites within the substantia nigra zona
reticulata of the rat brain. Neuroscience 61:285 – 292.Hold KM, Sirisoma NS,Ikeda T, Narahashi T, Casida JE. (2000) Alpha-
thujone (the active component of absinthe): gamma-aminobutyricacid type a receptor modulation and metabolic detoxification. Pro-ceedings of the National Academy of Sciences of the United Statesof America 97:3826 – 3831.
Hori A, Tandon P, Holmes GL, Stafstrom CE. (1997) Ketogenic diet:effects on expression of kindled seizures and behavior in adult rats. Epilepsia 38:750 – 758.
Hulbert AJ, Else PL. (2000) Mechanisms underlying the cost of livingin animals. Annual Review of Physiology 62:207 – 235.
Huttenlocher PR, Wilbourn AJ, Signore JM. (1971) Medium-chaintriglycerides as a therapy for intractable childhood epilepsy. Neu-rology 21:1097 – 1103.
Huttenlocher PR. (1976) Ketonemia and seizures: metabolic and an-ticonvulsant effects of two ketogenic diets in childhood epilepsy. Pediatric Research 10:536 – 540.
Iadarola MJ, Gale K. (1982) Substantia nigra: site of anticonvulsantactivity mediated by gamma-aminobutyric acid. Science 218:1237 – 1240.
Jaburek M, Varecha M, Gimeno RE, Dembski M, Jezek P, Zhang M,Burn P, Tartaglia LA, Garlid KD. (1999) Transport function andregulation of mitochondrialuncoupling proteins 2 and3. The Journalof Biological Chemistry 274:26003 – 26007.
Jovanovic S, Du Q, Crawford RM, Budas GR, Stagljar I, JovanovicA. (2005) Glyceraldehyde 3-phosphate dehydrogenase serves as anaccessory protein of the cardiac sarcolemmal k(atp) channel. EMBO Reports 6:848 – 852.
Kann O, Kovacs R, Njunting M, Behrens CJ, Otahal J, Lehmann TN,Gabriel S, Heinemann U. (2005) Metabolic dysfunction during neu-ronal activation in the ex vivo hippocampus from chronic epileptic
rats and humans. Brain 128:2396 – 2407.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
14/16
56 K. J. BOUGH AND J. M. RHO
Kashiwaya Y, Takeshima T, Mori N, Nakashima K, Clarke K, VeechRL. (2000) D-beta-hydroxybutyrate protects neurons in models of alzheimer ’s and parkinson’s disease. Proceedings of the National Academy of Sciences of the United States of America 97:5440 – 5444.
Keith HM. (1933) Factors influencing experimentally produced convul-sions. Archives of Neurology Psychiatry 29:148 – 154.
Kinsman SL, Vining EP, Quaskey SA, Mellits D, Freeman JM. (1992)
Efficacyof the ketogenic dietfor intractableseizure disorders:reviewof 58 cases. Epilepsia 33:1132 – 1136.
Kossoff EH, Pyzik PL, McGrogan JR, Vining EP, Freeman JM. (2002)Efficacy of the ketogenic diet for infantile spasms. Pediatrics109:780 – 783.
Kossoff EH, Krauss GL, McGrogan JR, Freeman JM. (2003) Efficacyof the atkins diet as therapy for intractable epilepsy. Neurology61:1789 – 1791.
Kossoff EH, McGrogan JR. (2005) Worldwide use of the ketogenic diet. Epilepsia 46:280 – 289.
Kossoff EH,McGrogan JR,Bluml RM, PillasDJ, RubensteinJE, ViningEP. (2006) A modified atkins diet is effective for the treatment of
intractable pediatric epilepsy. Epilepsia 47:421 – 424.Kovacs R, Schuchmann S, Gabriel S, Kardos J, Heinemann U. (2001)
Ca2+ signalling and changes of mitochondrial function during low-mg2+-induced epileptiform activity in organotypic hippocampalslicecultures.The EuropeanJournal of Neuroscience 13:1311 – 1319.
Kovacs R, Schuchmann S, Gabriel S, Kann O, Kardos J, Heinemann U.(2002) Free radical-mediated cell damage after experimental statusepilepticus in hippocampal slice cultures. Journal of Neurophysiol-ogy 88:2909 – 2918.
Kudin AP, Kudina TA, Seyfried J, Vielhaber S, Beck H, Elger CE, KunzWS. (2002) Seizure-dependent modulation of mitochondrial oxida-tive phosphorylation in rat hippocampus. The European Journal of Neuroscience 15:1105 – 1114.
Kunz WS, Kudin AP, Vielhaber S, Blumcke I, Zuschratter W, SchrammJ, Beck H, Elger CE. (2000) Mitochondrial complex i deficiency inthe epileptic focus of patients with temporal lobe epilepsy. Annalsof Neurology 48:766 – 773.
Layton ME, Pazdernik TL. (1999) Reactive oxidant species in piriformcortex extracellular fluid during seizures induced by systemic kainicacid in rats. Journal of Molecular Neuroscience 13:63 – 68.
Leaf A, Kang JX. (1996) Prevention of cardiac sudden death by n-3
fatty acids: a review of the evidence. Journal of Internal Medicine240:5 – 12.
Leaf A, Xiao YF, Kang JX, Billman GE. (2003) Prevention of suddencardiac death by n-3 polyunsaturated fatty acids. Pharmacology &Therapeutics 98:355 – 377.
Lesage F. (2003) Pharmacology of neuronal background potassiumchannels. Neuropharmacology 44:1 – 7.
Likhodii S, Burnham WM. (2004) Epilepsy and the ketogenic diet. In-StafstromCE, RhoJM (Eds).The effectsof ketonebodieson neuronalexcitability. Humana Press, Inc., Totowa, NJ, pp. 217 – 228.
Likhodii SS, Musa K, Mendonca A, Dell C, Burnham WM, CunnaneSC. (2000) Dietary fat, ketosis, and seizure resistance in rats on theketogenic diet. Epilepsia 41:1400 – 1410.
Likhodii SS, Serbanescu I, Cortez MA, Murphy P, Snead OC, III, Burn-ham WM. (2003) Anticonvulsant properties of acetone, a brain ke-tone elevated by the ketogenic diet. Annals of Neurology 54:219 – 226.
LivingstonS. (1972)Comprehensive management of epilepsy in infancy,childhood and adolescence. In Livingston S (Ed) Dietary treatment of epilepsy. Charles C. Thomas, Springfield, IL, pp. 378 – 405.
Mady MA,KossoffEH, McGregor AL,WhelessJW, Pyzik PL,FreemanJM. (2003) The ketogenic diet: adolescents can do it, too. Epilepsia44:847 – 851.
Mahoney AW, Hendricks DG, Bernhard N, Sisson DV. (1983) Fastingand ketogenic diet effects on audiogenic seizures susceptibility of magnesium deficient rats. Pharmacology, Biochemistry, and Behav-ior 18:683 – 687.
Mak SC, Chi CS, Wan CJ. (1999) Clinical experience of ketogenic dieton children with refractory epilepsy. Acta Paediatrica Taiwanica40:97 – 100.
Melo TM,Nehlig A, SonnewaldU. (2006) Neuronal-glial interactionsin
rats fed a ketogenic diet. Neurochemistry International 48:498 – 507.
Millichap JG, Jones JD, Rudis BP. (1964) Mechanism of anticonvulsantaction of ketogenic diet. American Journal of Diseases of Children107:593 – 604.
Morris AA. (2005) Cerebral ketone body metabolism. Journal of Inher-ited Metabolic Disease 28:109 – 121.
Muller-Schwarze AB, Tandon P, Liu Z, Yang Y, Holmes GL, StafstromCE. (1999) Ketogenic diet reduces spontaneous seizures and mossyfiber sprouting in thekainicacid model. Neuroreport 10:1517 – 1522.
Nakazawa M, Kodama S, Matsuo T. (1983) Effects of ketogenic dieton electroconvulsive threshold and brain contents of adenosine nu-cleotides. Brain & Development 5:375 – 380.
Noh HS, Lee HP, Kim DW, Kang SS, Cho GJ, Rho JM, Choi WS.(2004) A cdna microarray analysis of gene expression profiles in rathippocampus following a ketogenic diet. Brain Research. Molecular Brain Research 129:80 – 87.
Noh HS, Hah YS, Nilufar R,HanJ, BongJH,Kang SS, Cho GJ, ChoiWS.(2006)Acetoacetate protects neuronal cellsfrom oxidativeglutamatetoxicity. Journal of Neuroscience Research 83:702 – 709.
Nordli DR, Jr., Kuroda MM, Carroll J, Koenigsberger DY, Hirsch LJ,Bruner HJ, Seidel WT, De Vivo DC. (2001) Experience with theketogenic diet in infants. Pediatrics 108:129 – 133.
Nordoy A. (1999) Dietary fatty acids and coronary heart disease. Lipids34(suppl):S19 – 22.
Otani K, Yamatodani A, Wada H, Mimaki T, Yabuuchi H. (1984) [Effectof ketogenic diet on the convulsive threshold and brain amino acidand monoamine levels in young mice]. No To Hattatsu 16:196 – 204.
Pan JW, Bebin EM, Chu WJ, Hetherington HP. (1999) Ketosis andepilepsy: 31p spectroscopic imaging at 4.1 t. Epilepsia 40:703 – 707.
Pelicano H, Martin DS, Xu RH, Huang P. (2006) Glycolysis inhibitionfor anticancer treatment. Oncogene 25:4633 – 4646.
Peterson SJ, Tangney CC, Pimentel-Zablah EM, Hjelmgren B, Booth G,Berry-Kravis E. (2005) Changes in growth and seizure reduction inchildren on the ketogenic diet as a treatment for intractable epilepsy. Journal of the American Dietetic Association 105:718 – 725.
Puchowicz MA, Emancipator DS, Xu K, Magness DL, Ndubuizu OI,Lust WD, LaManna JC. (2005) Adaptation to chronic hypoxia dur-ing diet-induced ketosis. Advances in Experimental Medicine and Biology 566:51 – 57.
Rhim H, Kinney GA, Emmerson PJ, Miller RJ. (1997) Regulation of neurotransmission in the arcuate nucleus of the rat by different neu-ropeptide y receptors. The Journal of Neuroscience 17:2980 – 2989.
Rho JM, Kim DW, Robbins CA, Anderson GD, Schwartzkroin PA.(1999) Age-dependent differences in flurothyl seizure sensitivityin mice treated with a ketogenic diet. Epilepsy Research 37:233 – 240.
Rho JM, Anderson GD, Donevan SD, White HS. (2002) Acetoac-
etate, acetone, and dibenzylamine (a contaminant in l-(+)-beta-hydroxybutyrate) exhibit direct anticonvulsant actions in vivo. Epilepsia 43:358 – 361.
Richichi C, LinEJ, Stefanin D, ColellaD, Ravizza T, Grignaschi G, Veg-lianese P, SperkG, DuringMJ, VezzaniA. (2004)Anticonvulsant andantiepileptogenic effects mediated by adeno-associated virus vector neuropeptide y expression in the rat hippocampus. The Journal of Neuroscience 24:3051 – 3059.
Saar K, Mazarati AM, Mahlapuu R, Hallnemo G, Soomets U, Kilk K,Hellberg S, Pooga M, Tolf BR, Shi TS, Hokfelt T, Wasterlain C,Bartfai T, Langel U. (2002) Anticonvulsant activity of a nonpeptidegalanin receptor agonist. Proceedings of the National Academy of
Sciences of the United States of America 99:7136 – 7141.Sampath H, Ntambi JM. (2004) Polyunsaturated fatty acid regulation of
gene expression. Nutrition Reviews 62:333 – 339.Sampath H, Ntambi JM. (2005) Polyunsaturated fatty acid regulation of
genes of lipid metabolism. Annual Review of Nutrition 25:317 – 340.Sato K, Kashiwaya Y, Keon CA, Tsuchiya N, King MT, Radda GK,
Chance B, Clarke K, Veech RL. (1995) Insulin, ketone bodies, andmitochondrial energy transduction. The FASEB Journal 9:651 – 658.
Schlanger S, Shinitzky M, Yam D. (2002) Diet enriched with omega-3 fatty acids alleviates convulsion symptoms in epilepsy patients. Epilepsia 43:103 – 104.
Schlifke I, Kuteeva E, Hokfelt T, Kokaia M. (2006) Galanin expressedin the excitatory fibers attenuates synaptic strength and generalizedseizures in the piriform cortex of mice. Experimental Neurology200:398 – 406.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
15/16
ANTICONVULSANT ACTIONS OF KETOGENIC DIET 57
Schwartz RH, Eaton J, Bower BD,Aynsley-Green A. (1989a)Ketogenicdiets in the treatment of epilepsy: short-term clinical effects. Devel-opmental Medicine and Child Neurology 31:145 – 151.
Schwartz RM, Boyes S, Aynsley-Green A. (1989b) Metabolic effects of three ketogenic diets in the treatment of severe epilepsy. Develop-mental Medicine and Child Neurology 31:152 – 160.
Schwartzkroin PA. (1999) Mechanisms underlying the anti-epileptic ef-ficacy of the ketogenic diet. Epilepsy Research 37:171 – 180.
Seino S, Miki T. (2003) Physiological and pathophysiological roles of atp-sensitive k+ channels. Progress in Biophysics and Molecular Biology 81:133 – 176.
Seymour KJ, Bluml S, Sutherling J, Sutherling W, Ross BD. (1999)Identification of cerebral acetone by 1h-mrs in patients with epilepsycontrolled by ketogenic diet. Magma 8:33 – 42.
Shyng SL, Nichols CG. (1998) Membrane phospholipid control of nu-cleotide sensitivity of katp channels. Science 282:1138 – 1141.
Sills MA, Forsythe WI, Haidukewych D, MacDonald A, Robinson M.(1986) The medium chain triglyceride diet and intractable epilepsy. Archives of Disease in Childho od 61:1168 – 1172.
Sirven J, Whedon B, Caplan D, Liporace J, Glosser D, O’Dwyer J,Sperling MR. (1999) The ketogenic diet for intractable epilepsy in
adults: preliminary results. Epilepsia 40:1721 – 1726.Smith SL, Heal DJ, Martin KF. (2005) Ktx 0101: a potential metabolic
approach to cytoprotection in major surgery and neurological disor-ders. CNS Drug Reviews 11:113 – 140.
Spurr NK. (2006) Pharmacogenetic studies of epilepsy drugs: are wethere yet? Trends in Genetics 22:250 – 252.
Stafstrom CE. (1999) Animal models of the ketogenic diet: whathave we learned, what can we learn? Epilepsy Research 37:241 – 259.
Stafstrom CE. (2004) Dietary approaches to epilepsy treatment: old andnew options on the menu. Epilepsy Currents 4:215 – 222.
Stafstrom CE, Kriegler SM, Valley MT, Ockuly JC, Roopra AS, Sutula
TP. (2005) 2-deoxyglucose exerts anticonvulsant and antiepilepticactions in experimental epilepsy models. Epilepsia 46:268 – 269.
Su SW, Cilio MR, Sogawa Y, Silveira DC, Holmes GL, Stafstrom CE.(2000)Timingof ketogenic dietinitiationin an experimental epilepsymodel. Brain Research Developmental Brain Research 125:131 – 138.
Sullivan PG, Dube C, Dorenbos K, Steward O, Baram TZ. (2003) Mi-tochondrial uncoupling protein-2 protects the immature brain from
excitotoxic neuronal death. Annals of Neurology 53:711 – 717.SullivanPG,RippyNA, Dorenbos K, Concepcion RC,AgarwalAK, Rho
JM. (2004) The ketogenic diet increases mitochondrial uncouplingprotein levels and activity. Annals of Neurology 55:576 – 580.
Szot P, Weinshenker D, Rho JM, Storey TW, Schwartzkroin PA. (2001)
Norepinephrine is required for the anticonvulsant effect of the keto-genic diet. Brain Research Developmental Brain Research 129:211 – 214.
Tabb K, Szot P, White SS, Liles LC, Weinshenker D. (2004) The ke-togenic diet does not alter brain expression of orexigenic neuropep-tides. Epilepsy Research 62:35 – 39.
Taha AY, Ryan MA, Cunnane SC. (2005) Despite transient ketosis, theclassic high-fat ketogenic diet induces marked changes in fatty acidmetabolism in rats. Metabolism 54:1127 – 1132.
Thavendiranathan P, Mendonca A, Dell C, Likhodii SS, Musa K, Ira-cleous C, Cunnane SC, Burnham WM. (2000) The mct ketogenicdiet: effects on animal seizure models. Experimental Neurology
161:696 – 703.Thavendiranathan P, Chow C, Cunnane S, McIntyre BW. (2003) The
effect of the ‘classic’ ketogenic diet on animal seizure models. Brain Research 959:206 – 213.
Thio LL,WongM, Yamada KA.(2000)Ketone bodies do notdirectly al-ter excitatory or inhibitory hippocampal synaptic transmission. Neu-rology 54:325 – 331.
Thio LL, Erbayat-Altay E, Rensing N, Yamada KA. (2006) Leptin con-tributes to slower weight gain in juvenile rodentson a ketogenic diet. Pediatric Research.
Thomzig A, Laube G, Pruss H, Veh RW. (2005) Pore-forming subunitsof k-atp channels, kir6.1 and kir6.2, display prominent differencesin regional and cellular distribution in the rat brain. The Journal of Comparative Neurology 484:313 – 330.
Uhlemann ER, Neims AH.(1972)Anticonvulsantproperties of theketo-
genic diet in mice. The Journal of Pharmacology and ExperimentalTherapeutics 180:231 – 238.
Vamecq J, Vallee L, LesageF, Gressens P, Stables JP.(2005)Antiepilep-tic popular ketogenic diet: emerging twists in an ancient story. Progress in Neurobiology 75:1 – 28.
Veech RL, Chance B, Kashiwaya Y, Lardy HA, Cahill GF Jr. (2001)Ketone bodies, potential therapeutic uses. IUBMB Life 51:241 – 247.
Veech RL. (2004) The therapeutic implications of ketone bodies: the
effects of ketonebodies in pathologicalconditions: ketosis,ketogenicdiet, redox states, insulin resistance, and mitochondrial metabolism. Prostaglandins Leukot Essent Fatty Acids 70:309 – 319.
Vezzani A, Moneta D, Conti M, Richichi C, Ravizza T, De Luigi A,De Simoni MG, Sperk G, Andell-Jonsson S, Lundkvist J, IverfeldtK, Bartfai T. (2000) Powerful anticonvulsant action of il-1 receptor antagonist on intracerebral injection and astrocytic overexpressionin mice. Proceedings of the National Academy of Sciences of theUnited States of America 97:11534 – 11539.
Vezzani A, Sperk G. (2004) Overexpression of npy and y2 receptors inepileptic brain tissue: an endogenous neuroprotective mechanism intemporal lobe epilepsy? Neuropeptides 38:245 – 252.
Vining EP, Freeman JM, Ballaban-Gil K, Camfield CS, Camfield PR,
HolmesGL, Shinnar S, ShumanR, Trevathan E, Wheless JW.(1998)A multicenter study of the efficacy of the ketogenic diet. Archives of Neurology 55:1433 – 1437.
Vining EP. (1999) Clinical efficacy of the ketogenic diet. Epilepsy Re-search 37:181 – 190.
Vining EP, Pyzik P, McGrogan J, Hladky H, Anand A, Kriegler S, Free-man JM. (2002) Growth of children on the ketogenic diet. Develop-mental Medicine and Child Neurology 44:796 – 802.
Vodickova L, Frantik E, Vodickova A. (1995) Neutrotropic effects andblood levels of solvents at combined exposures: binary mixtures of toluene, o-xylene and acetone in rats and mice. Central European Journal of Public Health 3:57 – 64.
Vreugdenhil M, Bruehl C, Voskuyl RA, Kang JX, Leaf A, Wadman WJ.
(1996) Polyunsaturated fatty acids modulate sodium and calciumcurrents in CA1 neurons. Proceedings of the National Academy of Sciences of the United States of America 93:12559 – 12563.
WangZJ,BergqvistC, HunterJV,Jin D,Wang DJ,Wehrli S,ZimmermanRA. (2003) In vivo measurement of brain metabolites using two-dimensional double-quantum mr spectroscopy – exploration of gabalevels in a ketogenic diet. Magnetic Resonance in Medicine 49:615 –
619.Weinshenker D, Szot P. (2002) The role of catecholamines in seizure
susceptibility: new results using genetically engineered mice. Phar-macology & Therapeutics 94:213 – 233.
Williamson A, Patrylo PR, Pan J, Spencer DD, Hetherington H. (2005)
Correlations between granule cell physiology and bioenergetics inhuman temporal lobe epilepsy. Brain 128:1199 – 1208.
Wu BJ, Hulbert AJ, Storlien LH, Else PL. (2004) Membrane lipidsand sodium pumps of cattle and crocodiles: an experimental test of the membrane pacemaker theory of metabolism. American Journalof Physiology. Regulatory, Integrative and Comparative Physiology287:R633 – 641.
Xiao Y, Li X. (1999) Polyunsaturated fatty acids modify mouse hip-pocampal neuronal excitability during excitotoxic or convulsantstimulation. Brain Research 846:112 – 121.
Xiao YF, Gomez AM, Morgan JP, Lederer WJ, Leaf A. (1997) Suppres-sion of voltage-gated l-type ca2+ currents by polyunsaturated fatty
acids in adult and neonatal rat ventricular myocytes. Proceedings of the National Academy of Sciences of the United States of America94:4182 – 4187.
Xiao YF, Wright SN, Wang GK, Morgan JP, Leaf A. (1998) Fatty acidssuppress voltage-gated Na+ currents in hek293t cells transfectedwith the alpha-subunit of the human cardiac Na+ channel. Proceed-ings of the National Academy of Sciences of the United States of America 95:2680 – 2685.
Xiong ZQ, Stringer JL. (2000) Sodium pump activity, not glial spatialbuffering, clears potassium after epileptiform activity induced in thedentate gyrus. Journal of Neurophysiology 83:1443 – 1451.
Yamada K, Ji JJ, Yuan H, Miki T, Sato S, Horimoto N, Shimizu T,Seino S, Inagaki N. (2001) Protective role of atp-sensitive potassiumchannels in hypoxia-induced generalizedseizure. Science 292:1543 – 1546.
Epilepsia, Vol. 48, No. 1, 2007
8/18/2019 Bough2007 Anticonvulsant Mechanisms of the Ketogenic Diet
16/16
58 K. J. BOUGH AND J. M. RHO
Yamashita M, Matsuki A, Oyama T. (1976) General anaesthesia for apatient with progressive muscular dystrophy. Anaesthesist 25:76 – 79.
Yan QS, Jobe PC, Dailey JW. (1993) Noradrenergic mechanisms for the anticonvulsant effects of desipramine and yohimbine in geneti-callyepilepsy-prone rats:studies with microdialysis. Brain Research610:24 – 31.
Young C, Gean PW, Chiou LC, Shen YZ. (2000) Docosahexaenoic acidinhibits synaptic transmission and epileptiform activity in the rat
hippocampus. Synapse 37:90 – 94.Yudkoff M, Daikhin Y, Nissim I, Grunstein R. (1997) Effects of ketone
bodies on astrocyte amino acid metabolism. Journal of Neurochem-istry 69:682 – 692.
Yudkoff M, Daikhin Y, Nissim I, Lazarow A. (2001) Brain amino acid
metabolism and ketosis. The Journal of Neuroscience Journal of Neuroscience Research 66:272 – 281.
Yudkoff M, Daikhin Y, Nissim I, Nissim I. (2004) Epilepsy and theketogenic diet. In Stafstrom CE, Rho JM (Eds) The ketogenic diet:interactions with brain amino acid handling. Humana Press, Inc.,Totowa, NJ, pp. 185 – 215.
Yudkoff M, Daikhin Y, Nissim I, Horyn O, Lazarow A, Luhovyy B,WehrliS. (2005)Responseof brainamino acidmetabolismto ketosis.
Neurochemistry International 47:119 – 128.Yuen AW, Sander JW, Fluegel D, Patsalos PN, Bell GS, Johnson T,
Koepp MJ. (2005) Omega-3 fatty acid supplementation in patientswith chronic epilepsy: a randomized trial. Epilepsy & Behavior 7:253 – 258.
E il i V l 48 N 1 2007