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Polychlorinated biphenyls (PCBs): in vivo quantitative structure activity relationships (QSARs) and interactive effects

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:6017903
The in vivo QSARs for nine PCB congeners were determined in the immature male Wistar rat. The ED25 and Ed50 values for hepatic microsomal aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD) induction, body weight loss and thymic atrophy were established. Hepatic Ah receptor binding affinities and receptor induction were measured for each of the PCBs studied. The coplanar PCBs; 3,3'4,5',5-penta- and 3,3'4,4'5,5'-hexachlorobiphenyl (HCBP) had the highest affinities for the Ah receptor but did not induce receptor levels. These compounds also had the greatest inducive effect on hepatic microsomal AHH and EROD activities, body weight loss and thymic atrophy. A Di-ortho substituted PCB 2,2'4,4'5,5'-HCBP showed a very low affinity for the Ah receptor protein but increased its levels over a period of 7 days (> 2 fold). Treatment of immature male Wistar rats with 2,2'4,4'5,5'-HCBP had no observable effects on AHH or EROD activities. Exposure of rats to 3,3'4,4'5,5'-HCBP previously treated with 2,2'4,4'5,5'-HCBP resulted in an apparent non-additive induction of both EROD and AHH hepatic microsomal activities. The results suggest that the interactive effects were due to increased hepatic Ah receptor levels.
Research Organization:
Brock Univ., St. Catharines, Ontario
OSTI ID:
6017903
Report Number(s):
CONF-870644-
Conference Information:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
Country of Publication:
United States
Language:
English