Journal
FASEB JOURNAL
Volume 25, Issue 2, Pages 644-652Publisher
FEDERATION AMER SOC EXP BIOL
DOI: 10.1096/fj.10-169227
Keywords
P-glycoprotein; multidrug resistance-associated protein 2; breast cancer resistance protein; dioxin; brain capillaries
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Funding
- National Institute of Environmental Health Sciences, National Institutes of Health
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Many widespread and persistent organic pollutants, e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), activate the aryl hydrocarbon receptor (AhR), causing it to translocate to the cell nucleus, where it transactivates target genes. AhR's ability to target the blood-brain barrier is essentially unexplored. We show here that exposing isolated rat brain capillaries to 0.05-0.5 nM TCDD roughly doubled transport activity and protein expression of P-glycoprotein, an ATP-driven drug efflux pump and a critical determinant of drug entry into the CNS. These effects were abolished by actinomycin D or cycloheximide or by the AhR antagonists resveratrol and alpha-naphthoflavone. Brain capillaries from TCDD-dosed rats (1-5 mu g/kg, i.p.) exhibited increased transport activity and protein expression of 3 xenobiotic efflux pumps, P-glycoprotein, multidrug resistance-associated protein 2, and breast cancer resistance polypeptide, as well as expression of Cyp1a1 and Cyp1b1, both AhR target genes. Consistent with increased P-glycoprotein expression in capillaries from TCDD-dosed rats, in situ brain perfusion indicated significantly reduced brain accumulation of verapamil, a P-glycoprotein substrate. These findings suggest a new paradigm for the field of environmental toxicology: toxicants acting through AhR to target xenobiotic efflux transporters at the blood-brain barrier and thus reduce brain accumulation of CNS-acting therapeutic drugs.-Wang, X., Hawkins, B. T., Miller, D. S. Aryl hydrocarbon receptor-mediated up-regulation of ATP-driven xenobiotic efflux transporters at the blood-brain barrier. FASEB J. 25, 644-652 (2011). www.fasebj.org
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