Aryl hydrocarbon hydroxylase (AHH) induction by polybrominated biphenyls (PBBs): Enhancement by photolysis

Larry W. Robertson, Andrew Parkinson, Brock Chittim, Stelvio Bandiera, Thomas W. Sawyer, Stephen Safe

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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 or fireMaster BP-6 to immature mall Wistar rats caused dose-related decreases in thymus weight and increases in hepatic microsomal benzo[a]pyrene hydroxylase (AHH), 4-dimethylaminoantypyrine 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). Futhermore, the concentration of photolyzed PBBs (2 μM) 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 μM), 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.

Original languageEnglish (US)
Pages (from-to)103-114
Number of pages12
Issue number2
StatePublished - 1981

ASJC Scopus subject areas

  • Toxicology


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