title: Mechanism of action of the factor(s) secreted by rat seminiferous tubules and inhibiting interstitial cell testosterone production in vitro.
abstract: Rat seminiferous tubules secrete a factor which inhibits LH-dependent steroidogenesis by interstitial cells. The inhibitory activity was found to be specific for the testes, as cytosols from other rat tissues such as the kidney, heart, spleen, liver and epididymis had no significant effect on testosterone production by interstitial cells. Preliminary characterization by Ultrogel AcA 44 gel chromatography demonstrated that the active substance in SMST has a molecular weight between 40-50 kD. Spent medium from incubation of seminiferous tubules (SMST) caused a dose-dependent inhibition of LH-or cholera toxin-stimulated in vitro testosterone production by rat interstitial cells. However, SMST failed to inhibit forskolin-stimulated steroidogenesis. The effect of SMST was not altered by pre-incubating the cells with the sulfhydryl reagent, N-ethylmaleimide. Considering the proposed mode of action of these modulators of adenylate cyclase activity, the present studies suggest that a high molecular weight testis specific factor acts through the guanine nucleotide-binding stimulatory regulatory protein of the adenylate cyclase complex to inhibit LH-dependent testosterone production by Leydig cells.
authors.affiliation: Pediatric Endocrinology Unit, Karolinska Hospital, Stockholm, Sweden.
authors.forename: V
authors.initials: V
authors.lastname: Syed
authors.forename: S A
authors.initials: SA
authors.lastname: Khan
authors.forename: M
authors.initials: M
authors.lastname: Lindh
authors.forename: E M
authors.initials: EM
authors.lastname: Ritzén
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D002850:Chromatography, Gel; D005576:Colforsin / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D007985:Leydig Cells / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D008970:Molecular Weight; D011506:Proteins / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012671:Seminiferous Tubules / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D011506:Proteins; D005576:Colforsin; D013739:Testosterone; D007986:Luteinizing Hormone; D002772:Cholera Toxin