Chlordecone pretreatment alters [14C]chlordecone and [14C]cholesterol transport kinetics in the perfused rat liver
Gilroy, D.J. | Carpenter, H.M. | Curtis, L.R.
Previous work demonstrated that pretreatment of mice with low doses of the organochlorine insecticide chlordecone (CD) altered the tissue disposition of a subsequent [14C]CD or [14C] cholesterol challenge dose. The profile of these changes was consistent with the induction of a protein integral to hepatic CD/cholesterol turnover. The present study was undertaken to confirm similar in vivo effects in the rat and to analyze potential CD-induced changes in hepatic transport kinetics in the perfused rat liver. For in vivo experiments, male, Sprague-Dawley rats were treated with CD (5, 15, or 40 mg/kg) and challenged 3 or 7 days later with a 5 mg/kg [14C[CD tracer dose. Rats challenged 3 days after treatment and evaluated 16 hr later showed a dose-dependent decrease in hepatic [14C]CD relative to controls. This decrease could not be attributed to alterations in liver mass or total liver lipid. For kinetics studies, rats received 15 mg/kg CD and livers were perfused 3 days later. Following a brief (5-7 min) single-pass perfusion, the perfusate was replaced with recirculating buffer containing albumin-bound [3H]oleic acid or high-density lipoprotein-bound [14C]CD or [14C]cholesterol. Livers from pretreated animals had significantly decreased rates of [14C]CD and [14C]cholesterol uptake. Efflux of [14C]CD and biliary excretion of [14C]cholesterol were increased. No changes were observed in uptake or biliary excretion of [3H]oleic acid. SDS-PAGE of hepatic cytosol revealed an enhanced band intensity corresponding to a Mr of 25,600 in livers from pretreated rats. These results are supportive of a competitive interaction between cholesterol and CD for proteins associated with hepatocellular transport and excretion and suggest that CD pretreatment may have an inductive effect on these proteins.
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