LH/hCG receptors and stimulation of testosterone biosynthesis in the rat testis: changes during foetal development in vivo and in vitro.
The development of gonadotropin receptors to LH/hCG in the foetal rat testis from 14 to 20 days of gestation was monitored by quantitative binding assays using [125I]hCG and compared to testosterone secretion under basal and stimulated conditions in vitro. Specific hCG binding was first detected on day 15. Thereafter the binding increased gradually with advancement in gestational age and correlated with LH-stimulated secretion of testosterone in vitro. On day 18 of gestation the KA was 0.82 x 10(10) M-1 and the binding capacity was 0.57 fmoles per testis. No binding was detectable in the female gonads at this age. The differentiation of hCG receptors obtained in vitro was very low, although it was sufficient to give a full response to LH with testosterone biosynthesis. The results of the present study suggest that functional receptors do not appear before the capacity to synthesize testosterone is expressed and that their appearance is not dependent on factors extrinsic to the testis. However, additional factors could be necessary for a full development of the receptors.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D009924:Organ Culture Techniques; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011974:Receptors, LH; D013737:Testis / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis*
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D013739:Testosterone; D003994:Bucladesine; D007986:Luteinizing Hormone