Antioxidant agents and physiological responses in

adult epileptic patients treated with lamotrigine

El¿bieta P³onka-Pó³torak1, Pawe³ Zagrodzki2,3, Fergus Nicol4, Jadwiga

Kryczyk2, Henryk Bartoñ2, Tuomas Westermarck5, Pekka Kaipainen5,

Sakaewan Ounjaijean5,6, Markus Kaski5, Faik Atroshi7

�Antiepileptic Outpatient Clinic, Provincial Hospital No. 2, Lwowska 60, PL 35-301 Rzeszów, Poland

�Department of Food Chemistry and Nutrition, Medical College, Jagiellonian University, Medyczna 9,

PL 30-688 Kraków, Poland

�Henryk Niewodniczañski Institute of Nuclear Physics, Radzikowskiego 152, PL 31-342 Kraków, Poland

�Vascular Health Division, Rowett Institute of Nutrition and Health, The University of Aberdeen, Bucksburn,

Aberdeen AB21 9SB, UK

�Rinnekoti Research Centre, FIN 02980 Espoo, Finland

�Faculty of Pharmacy, Payap University, Chiang Mai 50000, Thailand

�Department of Pharmacology and Toxicology, ELTDK, FIN 00014 University of Helsinki, Finland

Correspondence: El¿bieta P³onka-Pó³torak, e-mail: elapp13@wp.pl

Abstract:

Background: The aim of our research was to evaluate some biochemical changes in blood during lamotrigine (LTG) monotherapy

of adult patients with epilepsy, and to check possible associations between typical selenium status parameters and the frequency of

seizures.

Methods: The study was performed by examining aspartate aminotransferase (AspAT), alanine aminotransferase (AlaAT), creati-

nine, ferric reducing ability of plasma (FRAP), serum uric acid (UA), uric-acid-independent FRAP (UAiFRAP), plasma glutathione

peroxidase (GPX3), selenoprotein P (SelP), plasma superoxide dismutase (pSOD), 8-hydroxy-2’-deoxyguanosine (8-OHdG) in se-

rum and urine, serum selenium (sSe) and zinc (sZn), in 22 adult patients with epilepsy and 22 healthy controls. Additionally, the lev-

els of LTG were determined in patients.

Results: pSOD activity was higher in the study group (5.32 ± 1.24 U/ml) compared with the controls (4.05 ± 0.92 U/ml, p = 0.008).

No other statistical difference between patients and controls was found.

Conclusion: Lack of difference in parameters other than SOD, particularly no difference in 8-OHdG concentrations between the pa-

tients treated with LTG compared to the control subjects suggests that these patients are at no particular risk of oxidative DNA dam-

age. In patients who are well or moderately well clinically controlled, selenium status parameters (sSe, GPX3, SelP) are not directly

connected with the frequency of seizures.

Key words:

epilepsy, lamotrigine, oxidative stress, selenium, superoxide dismutase

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Abbreviations: AEDs – antiepileptic drugs, AlaAT – alanine

aminotransferase, AspAT – aspartate aminotransferase, FRAP –

ferric reducing ability of plasma, GPX3 – plasma glutathione per-

oxidase, IGE – idiopathic generalized epilepsy, 8-OHdG – 8-

hydroxy-2’-deoxyguanosine, LTG – lamotrigine, pSOD – plasma

superoxide dismutase, ROS – reactive oxygen species, SelP –

selenoprotein P, sSe – serum selenium concentration, sZn – serum

zinc concentration, UA – uric acid, UAiFRAP – uric-acid-

independent ferric reducing ability of plasma, VPA – valproate

Introduction

It is now acknowledged, as demonstrated for animal

models, that reactive oxygen species (ROS) are gener-

ated in the epileptic processes [29, 34]. The neuronal

and glial cells are particularly susceptible to ROS-

induced oxidative damages. The predisposing condi-

tions for enhanced oxidative stress in brain may arise

from various biological phenomena, including high

oxygen consumption by neurons, low concentration of

endogenous antioxidants and concomitant accumula-

tion of reactive iron, the abundance of polyunsaturated

fatty acids comprising brain lipids, and excess of pre-

dominant neurotransmiter glutamate, inducing cell tox-

icity [20, 29, 37]. Pharmacotherapy of epilepsy is often

long life and may result, as epilepsy itself does, in an

increase of oxidative stress. For this reason the antioxi-

dative defense mechanisms can play an important role

in both seizure control and side effects of drugs taken

by epileptic patients [4]. There are evidences that nutri-

tionally essential element – selenium, in accord with

other trace elements, may alleviate the consequences of

lesions caused by excitotoxic conditions [22, 29], while

the deficiency of this element in humans was linked

with epileptic seizures [3, 28, 36]. However, the neuro-

protective effect may be mediated via different mecha-

nisms, not exclusively associated with its role in anti-

oxidant enzymes [29].

In our previous study [26], we demonstrated sig-

nificant changes in antioxidant status in blood during

valproate (VPA) monotherapy of adult epileptic pa-

tients. We also revealed that the frequency of seizures

and duration of VPA therapy were associated with

changes of oxidative/antioxidative balance. Obvi-

ously, the underlying mechanisms of complex interac-

tions between pathological conditions, antiepileptic

drugs (AEDs), and neuroprotective mechanisms in

patients with epilepsy are still far from being fully dis-

cerned. Thus, focus in the present study was on the po-

tential clinical relevance of parameters characterizing

biochemical and antioxidant status in blood during la-

motrigine (LTG) monotherapy of adult patients with

epilepsy. Lamotrigine is a triazine compound [3,5-

diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine] with broad

spectrum of antiepileptic activity indicated for pri-

mary or secondarily generalized and partial seizures,

and Lennox-Gastaut syndrome [24]. LTG has multi-

ple mechanisms of actions, which are not fully eluci-

dated. It blocks voltage-gated sodium channels to sta-

bilize neuronal membranes, and inhibits release of the

excitatory amino acids [18]. LTG enhances cation

currents and alters dendritic h-channels, reducing the

excitability of neurons [17, 27]. The major metabolic

pathway for LTG is glucuronidation in the liver mi-

crosomes. LTG also undergoes hepatic and nonhe-

patic bioactivation to a reactive aryl epoxide interme-

diate, which can be related to the idiosyncratic cuta-

neous reactions or leucopenia associated with LTG

therapy [7]. Inactive metabolites are eliminated

mainly by renal excretion. Low protein binding

(55%), an absence of enzyme induction, and linear

pharmacokinetics are beneficial pharmacologic prop-

erties of LTG [23]. It has proven by numerous clinical

studies to be effective in the treatment of epilepsy

with a relatively low risk of side effects [33].

The information regarding the interactions between

lamotrigine and oxidative stress is scarce. In epileptic

patients treated either with VPA or LTG monothera-

pies, oxidative stress parameter – thiobarbituric acid

reactive substances – was elevated in VPA treated pa-

tients while it was normal in LTG group [8]. In line

with these results, treatment with lamotrigine was more

protective against oxidative stress in the cortex of the

brain and plasma in rats with experimentally induced

depression than the treatment with other medicines i.e.,

aripiprazole and escitalopram [10]. Similarly, Pavone

and Cardile proved that LTG at low concentrations, did

significantly change neither ROS production nor

lipoperoxidation level in antiepileptic drug treated pri-

mary rat astrocyte cultures [25]. Also in the study of

Agarwal et al. [1] LTG did not show significant altera-

tion in oxidative stress parameters during pentylenete-

trazole-kindling in mice. LTG treatment itself exerted

no significant effect on the levels of malondialdehyde,

reduced glutathione, superoxide dismutase and catalase

in non-kindled rats. The putative mild antioxidative LTG

activity was attributed to its inhibition of glutamate-

mediated excitotoxity through N-malondialdehde recep-

tors, which leads subsequently to lowering of ROS gen-

eration [2].

100 ������������� �� ����� ����� ��� �����

The current study was evaluated for detection of

possible changes, mainly in oxidant/antioxidant bal-

ance and selenium status, in the course of disease and

medical treatment with LTG, and to compare them (if

any) with those previously obtained for epileptic pa-

tients cured with VPA. The practical aspect of the

study was to indicate an antiepileptic drug which is

more advantageous in terms of oxidative stress pro-

tection. Plasma superoxide dismutase (pSOD), serum

zinc (sZn) concentration, and uric-acid-independent

ferric reducing ability of plasma (UAiFRAP) were de-

rived from our previous studies as the most sensitive

and relevant parameters (amid those studied) for char-

acterizing antioxidative defence mechanism, while

ferric reducing ability of plasma (FRAP) and serum

uric acid (UA) are auxiliary parameters for calculating

UAiFRAP values (see Methods section). Serum sele-

nium (sSe), selenoprotein P (SelP), and plasma glu-

tathione peroxidase (GPX3) are commonly acknowl-

edged as reliable selenium status parameters. The lat-

ter is also a major enzymatic antioxidant in plasma.

The levels of 8-hydroxy-2’-deoxyguanosine (8-OHdG)

in serum or urine provide information on systemic

oxidant/antioxidant status [12, 19]. The biochemical

parameters: aspartate aminotransferase (AspAT), al-

anine aminotransferase (AlaAT) and creatinine were

chosen to assess liver and renal functions in patients.

Patients

Fasting blood antioxidant status and diagnostic pa-

rameters’ levels were evaluated in 22 adult epileptic

patients (15 women and 7 men) receiving LTG anti-

convulsant monotherapy for at least 6 months (up to

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Antioxidant agents in epileptic patients�������� �� ������� �� ���

Tab. 1. Demographic and clinical characteristics of the patients and controls (data shown as the mean values ± standard deviations; n –number of subjects in each group)

Parameter

Groups of patients

Whole study group (n = 22)Mean ± SD (Min-Max)

Male (n = 7)Mean ± SD (Min-Max)

Female (n = 15)Mean ± SD (Min-Max)

Age (years) 27.9 ± 5.4 (20-43) 25 ± 4.5 (20-34) 28.2 ± 3.9 (23-43)

Body Mass Index (kg/m2) 22.5 ± 2.8 (19.3-25.5) 21.6 ± 2.8 (20.4-25.5) 22.8 ± 2.9 (19.3-28.9)

Time of LTG

monotherapy (years)

5.0 ± 2.2 (0.5-8) 5.4 ± 2.2 (0.5-8) 4.9 ± 23 (1-8)

Daily dose of LTG

(mg/d)

210 ± 98 (50-400) 207 ± 107 (75-400) 212 ± 98 (50-400)

Serum LTG

(μmol/l)

20.6 ± 12.8 (5.0-47.2) 20.3 ± 9.4 (11.5-39.8) 21.7 ± 14.4 (5.0-47.2)

Epilepsy diagnosis IGE, n (%) 10 (45%) 4 (57%) 6 (40%)

MRI/CT findings, n (%) 3 (14%) 2 (28%) 1 (7%)

EEG normal, n (%)

GED

Others

3 (14%)

7 (32%)

12 (54%)

1 (14%)

3 (43%)

3 (43%)

2 (13%)

4 (27%)

9 (60%)

Patients with seizures inyear/month before study, n (%)

13/5 (59% / 23%) 3/0 (43% / 0%) 10/5 (67% / 33%)

Parameter Groups of controls

Whole control group (n = 22)

Mean ± SD (Min-Max)

Male (n = 8)

Mean ± SD (Min-Max)

Female (n = 14)

Mean ± SD (Min-Max)

Age (years) 28 ± 6 (21-43) 26 ± 4 (21-34) 29 ± 6 (22-43)

Body Mass Index (kg/m2) 24.0 ± 3.7 (19.8-33.2) 25.7 ± 3.1 (21.1-30.4) 23.0 ± 3.8 (19.8-33.2)

n – number of cases, SD – standard deviation, IGE – idiopathic generalised epilepsy, MRI – magnetic resonance imaging, CT – computer tomo-graphy, EEG – electroencephalography, GED – generalized epileptiform discharges, Others – focal or/and background abnormalities

8 years). All of them were treated in the antiepileptic

outpatient clinic of the Provincial Hospital in Rzeszów

(Poland). Exclusion criteria were pregnancy, breast-

feeding, and progressive brain pathology. No restric-

tions were imposed on diet habits during the sampling

period. Demographic and clinical characteristics of the

patients and controls are shown in Table 1.

The patients were not treated with any medication

other than LTG and they did not suffer from any con-

comitant disease. They were clinically either well

(seizure free in the year preceding the current study,

n = 9), or moderately controlled (one to more than ten

seizures in the last year, but not more than ten fits per

month, n = 13). Among the patients with general

tonic-clonic seizures the number of fits per year was

not more than three, and they had not seizure in the

month of the study). No signs of overdosage or seri-

ous adverse events were observed. The differences in

daily dose of LTG between male and female patients

were not statistically significant. The types of epi-

lepsy were identified according to International

League Against Epilepsy classification [9]. The sub-

jects comprised of 10 cases with idiopathic general-

ized epilepsy (IGE), and 12 patients with other types

(non-IGE), including localization-related sympto-

matic or cryptogenic epilepsies, and undetermined, ei-

ther focal or generalized. The control group consisted

of 22 sex- and age-matched subjects. They were re-

cruited from the hospital staff and students.

The local Ethical Committee of Regional Chamber

of Physicians approved the plan of the study. The in-

formed consent was obtained from all the participants.

Methods

Plasma and serum samples were obtained as described

previously [26]. The morning, casual urine samples

were collected from all the patients and controls on the

same day, and kept frozen (–20°C) until analysis.

Apart from LTG in serum of patients, the following

parameters were determined: aspartate aminotransfe-

rase (AspAT), alanine aminotransferase, creatinine,

FRAP, UA, UAiFRAP, GPX3, SelP, pSOD, 8-OHdG

in serum and urine, sSe and sZn. AspAT, AlaAT, and

creatinine were determined on routine basis using ma-

terials from Thermo Fisher Scientific Oy Clinical Di-

agnostics, Finland, and according to the manufactur-

er’s instructions. The assays for FRAP, uric acid,

pSOD and GPX3 were performed as previously de-

scribed [26]. UAiFRAP was calculated by subtracting

doubled UA molar concentration from FRAP [5].

Electrothermal atomic absorption spectrometric meas-

urements of sSe concentrations were performed on

a Perkin Elmer Model 5100 ZL. Serum zinc was de-

termined by electrothermal atomic absorption spec-

trometry by means of AAS-30 spectrometer (Carl-

Zeiss, Germany). The validity and accuracy of the se-

lenium and zinc determination were checked by a cer-

tified reference material SeronormTM Trace Ele-

ments Serum. The results indicated that analytical

procedures were reliable. For SelP determination

high-binding, 96 well plates (Greiner) were coated

with 100 μl antibody diluted in PBS (raised against

peptides by Eurogentec, and purified at RINH) and

incubated for 2 h at 37°C. The antibody solutions

were discarded and the plates washed with PBS con-

taining 0.05% Tween-20 and blocked overnight at

room temperature with 0.5% casein in PBS. Sixty μl

of samples or standards were mixed with 60 μl of

mouse monoclonal antibody (clone 37A1 AbFrontier,

Korea; diluted 1 : 1500) in round bottomed, 96 well

plates and stored overnight at 4°C. The next day, the

blocker in the high-binding plates was discarded and

they were washed 3 times with PBS containing 0.05%

Tween-20. A hundred μl of sample or standard was

transferred to the respective high-binding plate and

incubated at 37°C. After 2 h, the samples and stan-

dards were discarded and the plates washed again

3 times with PBS/Tween-20. A hundred μl of anti-

mouse HRP-linked antibody #7076 (1 : 5000) was

added and incubated at 37°C with shaking for 1 h.

The anti mouse HRP was discarded and the plates

washed 3 times with PBS/Tween-20. A hundred μl

TMB (KPL, USA) was added to each well and incu-

bated at room temperature for up to 30 min. Each

sample was analyzed in duplicate at two different di-

lutions (0.5 μl and 1 μl of plasma/well). Standards of

pure SelP were incubated alongside the samples

(range 0.25–16 ng/well) and a pooled plasma from the

previous study was used as a quality control. The lev-

els of LTG in serum of patients were evaluated by

high-performance liquid chromatography [11]. Uri-

nary and serum 8-OHdG concentrations were deter-

mined using an ELISA kit (Cayman Chemical, USA),

according to the method of Kikuchi et al. [16].

The set of parameters was completed by weight,

height, age, the type of epilepsy, the frequency of sei-

zures, magnetic resonance imaging (MRI) or com-

102 ������������� �� ����� ����� ��� �����

puter tomography (CT) and electroencephalography

(EEG) findings, duration of LTG monotherapy, level

and daily dose of LTG. The daily selenium intake (I��)

was evaluated using equation:

ISe [μg/d] = (sSe [μg/l] – 3.1)/1.62 [35].

Statistical approach

All the data were presented as the mean ± SD and

within a minimum-maximum range. Comparisons be-

tween groups were performed using either Student

t-test for parameters with normal distributions and ho-

mogenous variances, or Mann-Whitney test for un-

paired samples in all other cases and when the median

values were compared. The differences of p values <

0.05 were considered statistically significant. For sele-

nium status parameters, the Spearman rank correlation

coefficients (R�) were calculated. Statistical evaluations

were done with the commercially available package

STATISTICA PL v.10 (StatSoft, Tulsa, USA).

Results

Descriptive statistics of clinical and biochemical pa-

rameters are shown in Table 2. The only parameter

that differed between the patients and controls was

pSOD. Overall activity of pSOD was higher in the

study group compared with controls (p = 0.008; me-

dian values: 5.46 vs. 4.06 U/ml, Fig. 1). When both

groups (the study group and controls) were subdi-

vided according to sex, the difference did not reach

statistical significance. There was also no difference

in this parameter between the patients with or without

seizures in the last year and controls, as well as be-

tween overweight (n = 4, BMI > 25 kg/m�) and those

with normal BMI. The uncontrolled patients (i.e., pa-

tients with seizures) did not differ with the controlled

patients or control subjects in respect to any bio-

chemical parameter studied.

There was a significant correlation between sSe

and SelP in patients (R� = 0.438, p < 0.05).

Discussion

The patients in the present study received LTG in

monotherapy as the second or next line AED due to

intolerance or lack of efficacy of classic AEDs. Ac-

cording to the health care rules in Poland, LTG is re-

funded only in cases of drug resistance epilepsy, so its

availability to many patients is restricted. Thus, the

number of patients who fulfilled all the enrolling cri-

teria to this study was limited.

Every patient underwent a routine EEG examina-

tion in the year of the study for classification of epi-

lepsy and selection of its proper control. As none of

the patients had general tonic-clonic seizure in the

month preceding the study, the influence of this kind

of seizures on the tested parameters can be neglected.

However, as carrying out EEG examination exactly

on the day of the study was not possible for technical

reasons, we cannot exclude the influence of subclini-

cal EEG discharges on the results.

Most of the patients and controls appeared well

nourished, as 95% of patients and 100% of controls

had BMI above lower limit. They had correct liver

and renal function with normal levels of AspAT,

AlaAT and creatinine, respectively. It should be also

noted that although GPX3 activity was limited by se-

rum selenium concentration (Tab. 2), considerably

lower than required for optimal synthesis and activity

of this enzyme, the patients had no clinical evidence

of any selenium responsive disorder.

������������� �� ����� ����� ��� ����� 103

Antioxidant agents in epileptic patients�������� �� ������� �� ���

Study group Controls1

2

3

4

5

6

7

8

pS

OD

acti

vit

y[U

/ml]

Median

25%-75%

Min-Max

Fig. 1. Plasma SOD activity in study group (n = 22) and controls(n = 22) (two outlying healthy subject were excluded). Median values,25�� and 75�� centiles, minimal and maximal values were depicted.The difference between groups was evaluated by means of Mann-Whitney test, p = 0.008

SOD is a major antioxidant enzyme in the brain

[32]. In the current study we found increased level of

pSOD in LTG treated patients (Tab. 2). When we com-

pared (using Mann-Whitney test) our current results

with those previously obtained for the group of patients

(11 women and 10 men) receiving valproate monother-

apy (cf. [26], see also the whole set of corresponding

results) we found significantly higher pSOD activity in

patients treated with LTG (median value: 5.46 U/ml vs.

4.22 U/ml, p = 0.002). The patients in LTG group had

also higher UAiFRAP (median values: 121 μM Fe/l vs.

75 μM Fe/l, p = 0.043), which confirms our previous

hypothesis that VPA treatment per se induces oxidative

stress. This is manifested by lowering the levels of the

low molecular plasma antioxidants e.g., ascorbates and

tocopherols mainly responsible for changes in UAi-

FRAP values in such patients [26].

In the current study, we tested whether the 8-OHdG

levels would be useful in evaluating oxidative stress

in epileptic patients, and could discriminate between

them and healthy subjects. However, the values of 8-

OHdG did not allow distinguishing the LTG treated

epileptic patients from the controls. This suggests that

such patients are at no particular risk of oxidative

DNA damage. This could be reconciled with clinical

and epidemiological data about increased risk of ma-

lignancy, and cancer morbidity among epileptic pa-

tients treated with different medicines. The other pos-

sibility is that the rise in DNA damage can be attenu-

ated by the induction of repair systems. Of relevance

to our findings is the fact that the values of 8-OHdG

in an individual depend on a variety of other con-

founding effects (e.g., variation between different tis-

sues in rates of oxidative DNA damage and repair)

[12], which were not evaluated in the present study. It

is worth noting that 8-OHdG concentration in serum

was significantly higher in the VPA group (median

values: 3.72 vs. 2.73 pg/ml, p = 0.014) [26]. Similarly,

Schulpis et al. [31], who evaluated oxidative status in

epileptic children treated with VPA, found that pa-

tients with higher VPA serum levels had enhanced se-

rum 8-OHdG as compared with those with lower VPA

levels and healthy controls. They concluded that 8-

OHdG evaluations might be a useful procedure to fol-

low up the increased risk of degeneration processes

in patients treated with VPA. Our results indicate that

104 ������������� �� ����� ����� ��� �����

Tab. 2. The main descriptive statistics of all clinical and biochemical parameters in the study group and in healthy volunteers (data shown asthe mean values ± standard deviations)

ParameterStudy group Healthy volunteers

Unit Mean ± SD Min Max Mean ± SD Min Max p

Age year 27 ± 5 20 43 28 ± 6 21 43 NS1

BMI kg/m2 22.5 ± 2.8 16.6 28.9 24.0 ± 3.7 19.8 33.2 NS2

AspAT IU/l 24 ± 8 15 49 20 ± 4 13 31 NS2

AlaAT IU/l 23 ± 15 1 66 20 ± 11 10 58 NS2

Creatinine mg/dl 0.76 ± 0.13 0.50 1.10 0.76 ± 0.12 0.60 1.00 NS2

FRAP μM Fe/l 691 ± 100 508 878 712 ± 126 491 945 NS1

UA μM/l 294 ± 61 178 422 306 ± 66 202 452 NS1

UAiFRAP μM Fe/l 123 ± 56 33 232 124 ± 67 19 280 NS1

GPX3 U/ml 0.406 ± 0.109 0.218 0.652 0.448 ± 0.172 0.164 0.823 NS2

SelP μg/ml 4.72 ± 0.86 2.70 6.02 5.08 ± 1.14 3.39 8.13 NS2

pSOD U/ml 5.32 ± 1.24 2.82 6.95 4.05 ± 0.92 2.17 5.84 0.0082,3

8-OHdGin serum pg/ml 3.03 ± 0.99 1.82 5.43 3.10 ± 1.22 0.60 6.57 NS2

8-OHdGin urine pg/ml 29.5 ± 18.5 8.8 76.4 37.3 ± 20.1 11.2 101.0 NS1

sSe μmol/l 0.77 ± 0.16 0.40 1.05 0.84 ± 0.14 0.57 1.10 NS1

sZn μmol/l 11.7 ± 2.5 8.6 16.8 12.9 ± 4.0 8.9 25.1 NS2

� – Result of Student t-test; � – result of Mann-Whitney test, � – two outlying healthy volunteers with pSOD = 26.79 U/ml and 19.02 U/ml, respec-tively, were rejected from calculations

8-OHdG is not a useful biomarker of oxidative dam-

age of DNA or oxidant induced base modifications in

patients with LTG monotherapy.

Two selenium nutritional status parameters, sSe and

SelP correlated with each other in patients but with nei-

ther “antioxidant” parameters. Liver-derived, a sele-

nium-rich plasma SelP is mainly regarded as a sele-

nium storage and transport protein, though possessing

also detoxifying and antioxidant properties. The latter

ones are possibly by reducing phospholipid hydroper-

oxides in a glutathione peroxidase type 4 like manner

[6]. In our study, age, gender and taking LTG pills had

no effect on SelP concentration (data not shown). Lack

of influence of demographic factors on SelP is consis-

tent with results reported by Hill et al. [14].

Using the equation after Wasowicz [35], mean daily

selenium intake in LTG patients was 35.6 ± 8.0 μg/d

(the difference between LTG and VPA groups was not

significant) and the intake range was 17.4–49.1 μg/d.

This indicates that selenium status of the study group

was borderline, with some cases of mild selenium

deficiency, and concurrent large inter-individual

variation within the whole group. At present, such se-

lenium levels should be considered inadequate in rela-

tion to the Recommended Dietary Allowances for se-

lenium of 55 μg/d [15]. However, statistical analysis

for patients whose selenium status parameters (sSe,

GPX3 or SelP) were in the bottom quartile did not re-

veal any significant differences in the frequency of

seizures compared with respective top quartiles of pa-

tients. This finding indicates that typical selenium

status parameters are not directly associated with

a neuroprotective effect of selenium, at least in pa-

tients who are well or moderately well clinically con-

trolled. The protective potential of selenium in normal

brain functioning and ageing, as well as against neu-

rodegenerative disorders, e.g., excitotoxic brain dam-

age in epileptic patients, is provided by high brain Se

pool and putative involvement of selenium-containing

proteins [29]. It appears that SelP specific expression

in the brain renders it largely independent from

plasma selenium supply and bioavailability, including

contribution from circulating plasma SelP [30].

In several papers reviewed by Naziroglu [21], sele-

nium levels and blood glutathione peroxidase activi-

ties were lower in epileptic patients than in healthy

controls, although other authors did not confirm the

existence of such differences [13]. Our study provides

indirect evidence that the vital role of selenium me-

tabolism in the brain is apparently not hampered by

relatively low level of plasma indices of this element.

This obviously raises the question of which approach

for assessing selenium status should be adopted for

neuropreventive strategies and antiepileptic therapies.

Further studies are needed to address this problem.

Conclusions

We found significant increase only in pSOD activity

in the LTG treated patients compared with the con-

trols. The values of 8-OHdG did not distinguish be-

tween the LTG treated epileptic patients and the con-

trols, which suggests that such patients are at no par-

ticular risk of oxidative DNA damage.

Typical selenium status parameters (sSe, GPX3,

SelP) were not directly associated with the frequency

of seizures, at least in patients who are well or moder-

ately well clinically controlled.

Acknowledgments:

This study was partly supported by grant from Rinnekoti Research

Foundation. Dr. E. P³onka-Pó³torak has received support for her

attendance in congresses in epilepsy and neurology and speaker’s

honoraria from UCB-Pharma and Sanofi-Aventis. None of these

relations is related to the current submission. The remaining

authors confirm that there are no conflicts of interest.

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Received: June 2, 2012; in the revised form: August 14, 2012;

accepted: September 25, 2012.

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