Abstract
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
Akingbemi,Benson T.; Ge,Renshan; Klinefelter,Gary R.; Gunsalus,Glen L.; Hardy,Matthew P.
Biology of Reproduction 62(3): 571-578
Publication date: 2000
Postnatal development of Leydig cells involves transformationthrough three stages: progenitor, immature, and adult Leydigcells. The process of differentiation is accompanied by a progressiveincrease in the capacity of Leydig cells to produce testosterone(T). T promotes the male phenotype in the prepubertal periodand maintains sexual function in adulthood; therefore, disruptionof T biosynthesis in Leydig cells can adversely affect malefertility. The present study was designed to evaluate the abilityof a xenoestrogen, methoxychlor (the methoxylated isomer ofDDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane]), to alterLeydig cell steroidogenic function. Purified progenitor, immature,and adult Leydig cells were obtained from, respectively, 21-,35-, and 90-day-old Sprague-Dawley rats treated with gradedconcentrations of the biologically active metabolite of methoxychlor,2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), and assessedfor T production. HPTE caused a dose-dependent inhibition ofbasal and LH-stimulated T production by Leydig cells. Comparedto the control value, reduced T production by progenitor andimmature Leydig cells was apparent after 10 h of HPTE treatmentin culture; the equivalent time for adult Leydig cells was 18h. The reversibility of HPTE-induced inhibition was evaluatedby incubating Leydig cells for 3, 6, 10, 14, or 18 h and measuringT production after allowing time for recovery. After treatmentwith HPTE for 3 h, T production by immature and adult Leydigcells for the 18-h posttreatment period was similar to the controlvalue, but that of progenitor Leydig cells was significantlylower. The onset of HPTE action and the reversibility of itseffect showed that Leydig cells are more sensitive to this compoundduring pubertal differentiation than in adulthood. T productionwas comparable when control and HPTE-treated immature Leydigcells were incubated with pregnenolone, progesterone, and androstenedione,but HPTE-treated Leydig cells produced significantly reducedamounts of T when incubations were conducted with 22R-hydroxycholesterol(P < 0.01). This finding suggested that HPTE-induced inhibitionof T production is related to a decrease in the activity ofcytochrome P450 cholesterol side-chain cleavage enzyme (P450)and cholesterol utilization. The reduced steady-state mRNA levelfor P450 in HPTE-treated Leydig cells was demonstrated byreverse transcription-polymerase chain reaction and densitometry.In conclusion, this study showed that HPTE causes a direct inhibitionof T biosynthesis by Leydig cells at all stages of development.This effect suggests that reduced T production could be a contributoryfactor in male infertility associated with methoxychlor and,possibly, other DDT-related compounds.
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