title: CYP1A1 and CYP1B1 in blood-brain interfaces: CYP1A1-dependent bioactivation of 7,12-dimethylbenz(a)anthracene in endothelial cells.
abstract: Immunohistochemistry and autoradiography were used to identify sites of the cytochrome P450 enzymes (P450) 1A1 and 1B1 expression and activation of 7,12-dimethylbenz(a)anthracene (DMBA), in the brain of rodents pretreated with the aryl hydrocarbon receptor (AhR) agonists beta-naphthoflavone (BNF), 3,3',4,4',5-pentachlorobiphenyl or vehicle. Immunohistochemistry revealed that CYP1A1 was preferentially induced in endothelial cells (EC) in the choroid plexus, in veins in the leptomeninges, and in cerebral veins of AhR agonist-pretreated mice. No induction occurred in cerebral capillary EC. In vehicle-treated mice no localization of CYP1A1 in EC was observed. CYP1B1 was expressed in smooth muscle cells of arteries in the leptomeninges, in cerebral arteries/arterioles and to a low extent in ependymal cells of AhR agonist- and vehicle-treated mice. No CYP1B1 was detected in capillary loops of the choroid plexus or in cerebral capillaries. Following administration of [(3)H]DMBA to BNF-pretreated mice, a marked irreversible binding in EC of the choroid plexus and of veins in the leptomeninges was observed but not in cerebral capillaries. In vehicle-treated mice, there was no [(3)H]DMBA-binding at these sites. Furthermore, a high level of irreversibly bound [(3)H]DMBA occurred in EC at these sites in precision-cut mouse/rat brain slices and in excised blood-brain interfaces incubated with [(3)H]DMBA. Since [(3)H]DMBA binding sites corresponded with the sites of CYP1A1 induction, we conclude that rodents express a constitutively low but highly inducible and functional CYP1A1 in EC of some of the blood-brain interfaces. The role of CYP1A1/1B1 and environmental pollutants in the etiology of cerebrovascular disease needs further consideration.
authors.affiliation: Department of Pharmaceutical Biosciences, Biomedical Center, Uppsala University, Sweden.
authors.forename: Lizette
authors.initials: L
authors.lastname: Granberg
authors.forename: Anna
authors.initials: A
authors.lastname: Ostergren
authors.forename: Ingvar
authors.initials: I
authors.lastname: Brandt
authors.forename: Eva B
authors.initials: EB
authors.lastname: Brittebo
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000032:analysis / Q000493:pharmacokinetics*; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000032:analysis / Q000378:metabolism*; D001711:Biotransformation; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000032:analysis / Q000378:metabolism*; D065633:Cytochrome P-450 CYP1B1; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D001189:Aryl Hydrocarbon Hydroxylases; C585498:Cyp1b1 protein, mouse; C585499:Cyp1b1 protein, rat; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1