TESTICULAR GNRH-LIKE FACTORS - CHARACTERIZATION OF BIOLOGIC ACTIVITY

Observations that gonadotropin-releasing hormone [GnRH] and its agonists directly inhibit gonadal function by binding to receptors on the Leydig cells had led to search for testicular GnRH-like peptide(s). This communication presents evidence that GnRH-like factors isolated from rat testis by immunoaffinity chromatography and previously characterized by radioimmunoassay and radioreceptor assay possess biologic activity. The partially purified material led to dose-dependent inhibition of oLH [ovine luteinizing hormone] stimulated testosterone production in a mixed Sertoli-Leydig cell monolayer culture. Pre-incubation of the cells with a potent GnRH antagonist prevented the inhibitory effects of the partially purified material suggesting that inhibition of oLH-stimulated testosterone production may be receptor-mediated.