title: Aryl hydrocarbon hydroxylase (AHH) induction by polybrominated biphenyls (PBBs): enchancement by photolysis.
abstract: Irradiation of the commercial polybrominated biphenyl (PBB( mixture, fireMaster BP-6, in cyclohexane solution at 300 nm for 930 min resulted in a marked diminution of the major components of the mixture. Administration of the photolyzed PBB mixture of fireMaster BP-6 to immature male Wistar rats caused both dose-related decreases in thymus weight and increase in hepatic microsomal benzo[a]pyrene hydroxylase (AHH), 4-dimethylaminoantipyrine N-demethylase and NADPH-cytochrome c reductase activities and cytochrome P-450 content. The dose effecting half-maximal AHH induction for the photolyzed PBBs (9 mg . KG-1) was approximately 6 times lower than that of fireMaster BP-6 (50 mg. kg-1). Furthermore, the concentration of photolyzed PBBs (2 micrometers) required to displace 50% of the specifically-bound [3H] TCDD from its high-affinity cytosolic Ah receptor was approximately 150 times lower than that required for fireMaster BP-6 (300 micrometers), as measured by sucrose density gradient centrifugation analysis. The results suggest that the photolysis of the commercial PBB mixture yields products which possess increased biologic activity.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis*; D001713:Biphenyl Compounds / Q000633:toxicity*; D005411:Flame Retardants / Q000633:toxicity; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D010782:Photolysis; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001713:Biphenyl Compounds; D005411:Flame Retardants; D011075:Polybrominated Biphenyls; C015885:Firemaster BP-6; D001189:Aryl Hydrocarbon Hydroxylases