Authors
Li M-H, Hsu P-C, Guo YL.

Hepatic enzyme induction and acute endocrine effects of 2,2',3,3',4,6-hexachlorobiphenyl and 2,2'3,4,5,6-hexachlorobiphenyl in prepubertal female rats

This study examined the effects of 2 ubiquitous environmental polychlorinated biphenyls, 2,2',3,3,4,6-hexachlorobiphenyl ( PCB 132 ) and 2,2'3,4,5,6-hexachlorobiphenyl ( PCB 149) on uterine weight, serum thyroid hormone levels and hepatic cytochrome P450 enzyme activities in 24 day old Sprague-Dawley rats. Female rat pups at 20 days of age were injected intraperitoneally on days 21 and 22 with PCB 132 or PCB 149 at either 8, 32 or 96 mg/kg. PCB 132 is readily metabolized and thus indicative that an effect is due to a metabolite, while PCB 149 is not metabolized and suggests the effects of a parent compound. PCB 132 at all concentrations did not markedly affect uterine weight, serum thyroid hormone levels and hepatic cytochrome P 450 activities. PCB149 only at 32 mg/kg significantly lowered the concentration of serum thyroxine but no effect on triiodothyronine. The 96 mg/kg PCB 149 dose did not alter serum thyroxine levels. PCB 149 was not uterotrophic. Only the 96 mg/kg dose of PCB 149 significantly elevated hepatic cytochrome P450 enzymic activity. The lack of a dose-response effect of PCB149 on serum thyroid hormone levels and no change in uterine weight suggests that there is a lack of an acute endocrine disruptive effect attributable to this congener.