Low dose chlordecone pretreatment altered cholesterol disposition without induction of cytochrome P-450.

Pretreatment of mice with low doses of chlordecone (CD) alters the pattern of distribution of a subsequent tracer dose of [14C]CD. We call this preexposure effect a pretreatment disposition response (PDR) and suggest that it reflects important cellular responses to lipophilic compounds. The present study examined three possible mechanisms for CD-induced PDR (CD-PDR). The first was that CD-PDR occurred with induction of the cytochrome P-450 system. A cumulative dose of 45 mg/kg CD caused a PDR, increased the content of cytochrome P-450, and elevated the activities of ethoxyresorufin- and ethoxycoumarin-O-deethylases (EROD and ECOD). A cumulative dose of 10 mg/kg caused a PDR, but did not affect cytochrome P-450, EROD, or ECOD, indicating that an induction of the cytochrome P-450 system in not necessary for PDR. A second possibility examined was that CD-PDR resulted because of an altered affinity of a subcellular fraction. Following a pretreatment regimen designed to produce PDR, amounts of [14C]CD in each fraction paralleled homogenate values in the liver and the kidney. However, when values were calculated as percentages of total label recovered, it was apparent that [14C]CD levels were higher in the microsomal fraction of the liver. Finally, the possibility that CD-PDR occurred because of an interaction of CD with proteins involved in cholesterol synthesis and transport was addressed. CD pretreatment increased disposition of a dose of [14C]cholesterol to the fat at the expense of [14C]cholesterol in the liver and kidney.