title: The effects of testosterone and its 5alpha-reduced metabolites on pituitary responsiveness to gonadotrophin-releasing hormone (Gn-RH).
abstract: The aim of this study was to investigate effects of androgens on gonadotrophin release in response to gonadotrophin-releasing hormone (Gn-RH) stimulation in vitro. Hemipituitaries of mature male rats were pre-incubated for 90 min with T, DHT, 3alpha- or 3beta-diol (4 ng or 4 microgram/ml medium), and the incubation continued for 240 min after adding Gn-RH (1 ng/ml medium). Gn-RH caused a 4-5-fold rise in the secretion of LH and a 2-fold rise in FSH secretion. The effect of the androgens was dose-dependent. At low levels, T and DHT exerted no effect on Gn-RH-stimulated gonadotrophin release, whereas the two androstanediols (3alpha- and 3beta-diol) augmented the Gn-RH stimulation of both gonadotrophins, though preferentially LH. With high doses of androgens, the results obtained showed: a) no effect of T; b) DHT suppression of the Gn-RH-stimulated FSH release; c) suppression of Gn-RH stimulation by 3alpha- and 3beta-diol regarding both LH and FSH. It is concluded that T exerts through its reduced metabolites a feedback effect on the pituitary gland responsiveness to Gn-RH stimulation.
mesh_terms: D015113:Androstane-3,17-diol / Q000494:pharmacology*; D000731:Androstanes / Q000494:pharmacology*; D000818:Animals; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D009924:Organ Culture Techniques; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology*; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D000731:Androstanes; D010906:Pituitary Hormone-Releasing Hormones; D015113:Androstane-3,17-diol; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone