A metabolite of methoxychlor, 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane, reduces testosterone biosynthesis in rat leydig cells through suppression of steady-state messenger ribonucleic acid levels of the cholesterol side-chain cleavage enzyme

Postnatal development of Leydig cells involves transformation through three stages: progenitor, immature, and adult Leydig cells. The process of diffe rentiation is accompanied by a progressive increase in the capacity of Leyd ig cells to produce testosterone (T). T promotes the male phenotype in the prepubertal period and maintains sexual function in adulthood; therefore, d isruption of T biosynthesis in Leydig cells can adversely affect male ferti lity. The present study was designed to evaluate the ability of a xenoestro gen, methoxychlor (the methoxylated isomer of DDT [1,1,1 -trichloro-2,2-bis (p-chlorophenyl)ethan]), to alter Leydig cell steroidogenic function. Purif ied progenitor, immature, and adult Leydig cells were obtained from, respec tively, 21-, 35-, and 90-day-old Sprague-Dawley rats treated with graded co ncentrations of the biologically active metabolite of methoxychlor, 2,2-bis (p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), and assessed for T producti on. HPTE caused a dose-dependent inhibition of basal and LH-stimulated T pr oduction by Leydig cells. Compared to the control value, reduced T producti on by progenitor and immature Leydig cells was apparent after 10 h of HPTE treatment in culture; the equivalent time for adult Leydig cells was 18 h. The reversibility of HPTE-induced inhibition was evaluated by incubating Le ydig cells for 3, 6, 10, 14, or 18 h and measuring T production after allow ing time for recovery. After treatment with HPTE for 3 h, T production by i mmature and adult Leydig cells for the 18-h posttreatment period was simila r to the control value, but that of progenitor Leydig cells was significant ly lower. The onset of HPTE action and the reversibility of its effect show ed that Leydig cells are more sensitive to this compound during pubertal di fferentiation than in adulthood. T production was comparable when control a nd HPTE-treated immature Leydig cells were incubated with pregnenolone, pro gesterone, and androstenedione, but HPTE-treated Leydig cells produced sign ificantly reduced amounts of T when incubations were conducted with 22R-hyd roxycholesterol (P < 0.01). This finding suggested that HPTE-induced inhibi tion of T production is related to a decrease in the activity of cytochrome P450 cholesterol side-chain cleavage enzyme (P450(scc)) and cholesterol ut ilization. The reduced steady-state mRNA level for P450, in HPTE-treated Le ydig cells was demonstrated by reverse transcription-polymerase chain react ion and densitometry. In conclusion, this study showed that HPTE causes a d irect inhibition of T biosynthesis by Leydig cells at all stages of develop ment. This effect suggests that reduced T production could be a contributor y factor in male infertility associated with methoxychlor and, possibly, ot her DDT-related compounds.