M.C. Currás-CollazoDept. of Cell Biology & Neuroscience University of California, Riverside
The indoor flame retardants PBDEs disrupt cardiovascular and osmotic regulation: role of central nitric oxide and vasopressin
From: Kodavanti & Curras-Collazo, Frontiers in Neuroendocrinol. 2010
Persistent organic pollutants share a similar halogenated biphenyl structure
Biphenyl = diphenylTwo aromatic rings
Polyhalogenated: 209 possible congeners
PCBs used as heat exchangers/dielectrics, plasticizers
PBDEs used as indoor flame retardants
Chemical structure similar to thyroid and vasopressin hormones
www.eurofinsus.com/Services/Polybrominated%20Diphenyl%20Ether%20.html?gclid=CKCs8oS-6KQCFQoEbAodGhfb0w; M. J. La Guardia et al, 2006. Environ. Sci. Technol., 2006, 40, 6247–6254; http://www.doh.wa.gov/ehp/oehas/pbde/pbdeuse.htm
Why use flame retardants? To help prevent fire-related deaths (600) and injuries (47,000 in children)
PBDEs are blended into plastics and foams (constitute up to 30% of product); when exposed to flame and high heat, they release bromines that rob the air of the oxygen needed to start a fire.
Uses of industrial PBDE mixtures:PentaBDE (DE-60F, DE-61, DE-62, and DE-71): polyurethane foam (mattresses, seat cushions) OctaBDE (DE-79): high-impact plastics (fax, computers, cars, phones, kitchen appliances) DecaBDE (DE 83R and Saytex 102E): carpet and draperies, television sets, computers, cable insulation, adhesives (most widely used)
US is the world's largest producer and consumer of PBDEs. 95% of global pentaBDE and 44% of decaBDEs are used in the Americas.
The most abundant PBDE congeners in wildlife and humans are BDE-47 (tetra-) and 99 (penta-BDE).
Lower brominated PBDEs are the most toxic to thyroid, reproductive system and brain.
There are no product labels that list PBDEs and retailers generally are not aware which products contain PBDEs.
Inhalation of indoor dust (house,
office, car, airplane)
Breastmilk Occupation
Maternal transfer to fetus
Hand-to-mouth transfer
Diet (esp., fish)
salmon, ground beef, butter,
and cheese
Human Exposure to PBDE
http://www.agreenspan.org/mainsite/index.php?option=com_easygallery&act=photos&cid=29&Itemid=50; www.delta.dfg.ca.gov; http://www.doh.wa.gov/ehp/oehas/pbde/pbdehumanhealth.htm
Recent human studies on PBDEs
Highest PBDE levels in children reported in Chihuahua (Mexico), South China and Managua (Nicaragua) that work in waste sites or live in industrialized sites (Leung et al, 2010; Pérez-Maldonado et al., 2009; Athanasiadou et al., 2008).
In low-income California households the estimated daily non-dietary intake for PBDE 47 and 99 exceeded the US EPA recommended chronic reference dose for up to 5 children combined (Rose et al, 2010; Quiros-Alcala et al, 2011).
Maternal serum PBDE levels have been positively associated with lower scores on measures of intelligence and attention (Herbstman et al, 2010; Roze et al, 2009). Those with highest PBDEs in umbilical cord blood at birth showed lower scores on tests of mental and physical development between the ages 1-6. At 4 years, verbal and full IQ scores were reduced by as much as 5.5-8.0 points.
Women with higher blood levels of PBDEs took longer to become pregnant (Harley et al, 2010).
Children are at Special Risk: lactational transfer and ingestion of PBDEs
Body burdens (ng/g lipid wt):Adult (> 16 yr): 18 + 5 Children (0-4 yr): 73 + 7
Daily Intake of PBDE (ng/kg b.w.):Adults – 7.7 Toddlers- 49.9
Daily Intake of PBDE near e-waste site (ng/kg b.w.):
6 mo-old breastfed infants -2,240
US EPA recommended chronic reference dose for penta-BDE = 2,000 ng/kg/day
Total PCB Total PBDE
Toxi
cant
Lev
els
in B
reas
t Milk
(ng/
g lw
) n=4
0
0
20
40
60
80
100
120
140
160
She et al., (2007) Chemosphere 67: S307-S317
Lorber, M. (2007) J Expo Sci Environ Epidemiol.Toms, L.M., et al (2008) Environ Sci Technol. 42(19):7510-5.Leung et al, 2010 Environ Sci Poll Res. 17(7): 1300-1313.
Breast milk PBDEs in first–time mothersof Pacific Northwest and Canada
Concerns about PBDEs
Toxicology Findings:• Neurodevelopmental toxicity• Thyroid effects• Endocrine disruption• Some supporting human epidemiology
Exposure:• Primary exposure seems to be through house dust• Higher exposures for young children• Measured in human breast milk• Body burdens in U.S. much higher than in other countries• Debromination of decaBDEs
www.cartage.org.l
Objectives
• To determine the potential for neuroendocrine disruption by PBDEs
• To evaluate the effects of PBDEs on osmoregulation and cardiovascular reactivity to stress
PVN
SON
3V
OT
VP-NP antibody gift from Dr. Gloria Hoffman, University of Maryland, Baltimore, MD
Magnocellular neuroendocrine cell (MNC) system
2 locations:SON - supraopticPVN - paraventricular
2 populations:OxytocinVasopressin (VP)
From: Neuroscience: Exploring the Brain, Eds. Bear et al, Williams and Wilkins, New York, 1996.
MNCs are part of the hypothalamo-neurohypophysial system (HNS)
VP
VP
Stimuli:HyperosmolalityHypovolemia
Detectors:Osmoreceptors in forebrain
Effectors: Magnocellular neuroendocrine cells (MNCs)
Correctional mechanism:Water retention(kidney), vaso-constriction(blood vessels)
Somatodendritic (central VP release)
VPRVP
glu
G
MNC
Central VP binds to VP autoreceptors (VPR) to control firing rate, axonal VP output into blood and osmoregulation.
Modified from Dr. S. Qiu
Dual release of VP from MNCs may have autoregulatory function
SO
N V
P (p
g/m
l/ug)
0
1
2
3
4
5
6
b
normosmotic dehydrated
a
a
- PCB PCB in vitro(20 µM)
bb
acute exposure in vitro
*
1. Micro-dissection of SON
4. VP enzyme-linked immunoassay
2. Maintain tissue viable:Oxygenated and warm Microwells
3. In vitro testing –10 min collection
From: Coburn, Gillard and Curras-Collazo, 2005
CG Coburn, MC Curras-Collazo and PRS Kodavanti, Tox. Sci., 2007
In Vitro PCBs or PBDEs abolish stimulated release of central VP
PCBPBDE
*
0
2
4
6
8
10
12
14
**
#SO
N VP
Rele
ase
(pg
/ µg
prot
ein)
Normal Hyperosmotic control ----------------------------------------------------------------- Control DE-71 Aroclor 1254 ----------------------- ---------------------- 17.6 µg/ml 5.8 µg/ml 10 µg/ml 3.3 µg/ml30 µM 10 µM 30 µM 10 µM
3-5 hrs in vivo
Non-invasive monitoring of BP, HR
DE-71 dosing of dams (GD 6-PND 21) via Cheeto™ treats or oral gavage; 1.7 (low dose) or 30mg/kg/d (high dose)
3.5 M NaCl ip (6 ml/kg)
(Hyper)
0.15 M NaCl, ip
(Normal)
Acute osmotic challenge
Measure plasma osmolality
Sacrifice
Perinatal Exposure to DE-71
Plasma VP
Pregnant Dams14-18 months
Stabilization of BP after 3 weeks of acclimation
From: Shah et al, Toxicology and Applied Pharmacology (accepted)
Perinatal PBDE exposure alters blood pressure responses
From: Shah et al, Toxicology and Applied Pharmacology (accepted)
Perinatal exposure to DE-71 alters osmoregulation
From: Shah et al, Toxicology and Applied Pharmacology (accepted)
NORMAL HYPER
45 Minutes 3 Hour 45 Minutes 3 Hour
Oil 300.3± 2.1 (n=4) 301.2 ± 2.0 (n=4) 343.2 ± 8.8 (n=8)** 343.1 ± 6.9 (n=8)
PBDE Low
345.0 ± 10.7 (n=4)** 362.0 ± 12.1 (n=4)
PBDE High
325.1 ± 11.4 (n=4)* 358.3 ± 12.4 (n=4)#
PBDE All
335.1+8.2 (n=8)** 360.2+8.1 (n=8)╪
Plasma hyperosmolality is not due to insufficient VP release
From: Shah et al, Toxicology and Applied Pharmacology (accepted)
Summary & Conclusions• Acute in vitro application of PCBs or PBDEs interferes
with osmotic-stimulated central vasopressin release.
• Like PCBs, ingestion of PBDEs may disrupt stimulated plasma VP levels by reducing central VP signals.
• Perinatal exposure to the PBDE mixture DE-71 disrupts osmoregulation and increases cardiovascular reactivity to stress in late adulthood.
• Collectively, these results suggest that PCBs and PBDEs act as disruptors of neuroendocrine function, osmoregulation and cardiovascular function.
• The underlying mechanisms may include reduced thyroid status and/or vasopressin receptor density during development and/or renal toxicity.
AcknowledgementsUCR:Postdocs:Dr. E.R. Gillard
Graduate Students:Dr. Cary CoburnSamuel Mucios-Ramirez
Undergraduate Students:Borin HouChad CheethamAbena Watson-SiriboeAshini ShahRebecca WhitleyMark GaertnerAnoush Shahdizadeh Anna Carrera
Collaborators:Dr. M. Leon-Olea et al, Instituto Nacional de Psiquiatria, Mexico City, MexicoDr. P. Kodavanti, U.S. Environmental Protection Agency
ewg.org/pbdefree
• Some major manufacturers have publicly committed to eliminate all BFRs from their products world-wide in response to restrictions on toxic chemicals in electronic products sold in Europe and several U.S. states:
Acer, Apple, Eizo Nanao, LG Electronics, Lenovo, Matsushita, Microsoft, Nokia, Phillips, Samsung, Sharp, Sony-Ericsson, Toshiba.
• Some are phasing out decaPBDEs but not all BFRs: Canon, Daikin, Intel, IBM, HP, Minolta, Mitsubishi, Motorola, NEC, Nokia, Xerox.
Become an informed and selective consumer
• Blockade of central VP receptors elevate plasma VP levels ( ).• Hyperosmotic stimulation upregulate NOS in MNCs (Villar et al, 1994; Nylen et al,
2001).• NOS inhibitors exaggerate plasma VP and deplete pituitary VP content (Kadowaki
et al, 1994; Liu et al, 1998; Lutz-Bucher &Koch, 1994).
Like central VP, nitric oxide (NO) act as brake on pituitary VP release
Since PCBs block NO production (Sharma & Kodavanti, 2002)
Then….PCBs and similar compounds should reduce central VP and exaggerate plasma VP levels
Central NO leads to central VP• Hyperosmolality stimulates NO production and local release of NO within
the SON (Gillard et al, 2007).• Stimulated local VP release depends on central NO production (Gillard et
al, 2007).
Central Vasopressin System
Cardiovascular RegulationThermoregulationLearning & Memory Social & Reproductive BehaviorsReproductive FunctionAnxiety & Stress Responses
From: Kodavanti & Curras-Collazo, Frontiers in Neuroendocrinol. 2010
From: D. Axelrad, US EPA
From: D. Axelrad, US EPA
• In response to restrictions on toxic chemicals in electronic products sold in Europe and several U.S. states major some major manufacturers have publicly committed to eliminate all BFRs from their products world-wide: Acer, Apple, Eizo Nanao, LG Electronics, Lenovo, Matsushita, Microsoft, Nokia, Phillips, Samsung, Sharp, Sony-Ericsson, Toshiba.
• Some are phasing out decaPBDEs but not all BFRs: Canon, Daikin, Intel, IBM, HP, Minolta, Mitsubishi, Motorola, NEC, Nokia, Xerox.
Postnatal Day0 10 20 30 40 50 60
Seru
m T
hyro
xine
(ng/
ml)
0
10
20
30
40
50
60
70
Control 1.7 mg/kg/day 10.2 mg/kg/day 30.6 mg/kg/day
Male
Postnatal Day0 10 20 30 40 50 60
Seru
m T
hyro
xine
(ng/
ml)
0
10
20
30
40
50
60
70
Control 1.7 mg/kg/day 10.2 mg/kg/day 30.6 mg/kg/day
Female
***
**
*
**
*
**
Perinatal Exposure to the Industrial PBDE Mixture (DE-71)
Induces Transient Hypothyroidism
Kodavanti et al, 2010
Control 1.7 mg/kg 10.2 mg/kg 30.6 mg/kg
Tota
l Ser
um T
hyro
xine
(T4)
, ng/
ml
0
10
20
30
40
50
*
*
*
*
Industrial use of PBDEs as indoor flame retardants –mostly penta, octa and deca mixtures
Furniture & Automobile Upholstery (polyurethane) Foam
Electrical Appliances & Circuitry: computers, TVs,electrical appliances.
Plastics
Carpet Padding, Back Coatings for Draperies
Mattresses, foam items for infants and kids, toys
Building materials