Gonadotropin specificity of androgen secretion by amphibian testes

Abstract

Testes of amphibians representing three anuran and four urodelan families were examined for their abilities to secrete androgens in vitro in response to highly purified amphibian ( Rana) and ovine LH or FSH. A relatively high specificity for LHs over FSHs was found for Rana catesbeiana, Ambystoma tigrinum, and Bolitoglossa species. For Rana, testis pieces and dispersed testis cells responded similarly. Ovine and homologous Ambystoma LHs were highly active in Ambystoma, relative to the respective FSHs, and Rana LH was moderately more potent than Rana FSH. In contrast, androgen secretion by testes of Bufo marinus and Pseudoeurycea smithi was elicited by both gonadotropins; LH appeared to be somewhat more potent than FSH, but dose—response curves were not parallel. In Xenopus laevis, ovine gonadotropins were equally potent, and only a slight specificity for Rana LH over FSH was observed. For Taricha species, FSHs were generally equally potent to, or more potent than LHs. Homologous pituitary homogenate, but not Rana or ovine gonadotropins, stimulated androgen secretion by Necturus maculosus testes. Although LH specificity was observed in the two species in which homologous gonadotropins were tested ( Rana and Ambystoma), the results generally do not support the hypothesis of LH specificity for testicular androgen secretion in Amphibia.