title: Stimulatory and inhibitory factors of Leydig cell steroidogenesis are secreted simultaneously by the rat seminiferous tubules and do not affect Leydig cell inhibin production in vitro.
abstract: The effect of conditioned medium from rat seminiferous tubules (at Stages VII-VIII and Stages IX-VI) cultured with or without follicle-stimulating hormone (FSH) on the production of testosterone and immunoactive inhibin by Leydig cells was examined. Low doses of conditioned medium from unstimulated tubules at Stages VII-VIII significantly (P < 0.05) increased the mean testosterone production to greater than 31 +/- 11% over that achieved with luteinizing hormone (LH) alone. At the highest dose, the conditioned medium significantly inhibited (P < 0.05) LH-stimulated testosterone production by 13 +/- 7%. Low doses of conditioned medium from unstimulated tubules at Stages IX-VI increased the mean testosterone production to 22 +/- 10%, whereas at higher doses, a significant reversal in the stimulation occurred although not to the same extent as that found with medium from tubules at Stages VII-VIII. Conditioned medium from FSH-stimulated tubules at Stages VII-VIII and Stages IX-VI, significantly increased testosterone production to 39 +/- 7% and 31 +/- 13% respectively. Immunoactive inhibin production by the Leydig cells remained unaffected by exposure to conditioned medium from FSH stimulated and unstimulated tubules at Stages VII-VIII and Stages IX-VI. The data demonstrate that tubule culture medium contains FSH-modulated activities which can specifically stimulate and inhibit testosterone synthesis by adult rat Leydig cells in vitro and therefore explains the contradictory reports in the literature.
authors.affiliation: Institute of Reproduction and Development, Monash University, Clayton, Vic, Australia.
authors.forename: J R
authors.initials: JR
authors.lastname: McFarlane
authors.forename: D M
authors.initials: DM
authors.lastname: de Kretser
authors.forename: G P
authors.initials: GP
authors.lastname: Risbridger
mesh_terms: D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004305:Dose-Response Relationship, Drug; D005640:Follicle Stimulating Hormone / Q000032:analysis / Q000494:pharmacology; D007265:Inhibins / Q000378:metabolism*; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000032:analysis / Q000494:pharmacology; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012671:Seminiferous Tubules / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone