title: The interaction of hCG, hydroxysteroids and interstitial fluid on rat Leydig cell steroidogenesis in vitro.
abstract: Rat testicular interstitial fluid and hydroxycholesterol both stimulated testosterone production by isolated Leydig cells in vitro in a dose-dependent manner, but the dose-response lines were not parallel. The addition of cycloheximide blocked the stimulation by interstitial fluid but not that of hydroxycholesterol. Use of the compounds SU 10603 and cyanoketone (which inhibit 3 beta-hydroxysteroid dehydrogenase and 17 alpha-hydroxylase respectively) or aminoglutethimide (which acts on the cholesterol side-chain cleavage enzyme) showed that the stimulatory factor(s) in interstitial fluid stimulated steroidogenesis at the cholesterol side-chain cleavage enzyme, before the conversion of pregnenolone. This enzyme is rate-limiting in the synthesis of testosterone by Leydig cells and a site of action of LH; therefore, these results support the view that an interstitial fluid factor may be involved in the paracrine regulation of testicular steroidogenesis.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000378:metabolism*; D006888:Hydroxycholesterols / Q000494:pharmacology*; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D006063:Chorionic Gonadotropin; D006888:Hydroxycholesterols; C003585:22-hydroxycholesterol; D013739:Testosterone; C007997:25-hydroxycholesterol