Stimulatory effect of a GnRH agonist (buserelin) in in vitro and in vivo testosterone production by the frog ( Rana esculenta) testis

Abstract

The summary testicular effects of an agonistic analogue of gonadotropin-releasing hormone (buserelin, GnRHa) have been studied in vitro and in vivo in the frog, Rana esculenta. During 3 h incubation GnllHa (8 × 10 −7 M) potentiated pituitary factors in stimulating testosterone production by minced testes in vitro. After 6 h of incubation 8 × 10 −7 M GnRHa stimulated maximal testosterone output. Testes of 10-day hypophysectomized animals did not show any GnRHa effect in vitro. In vivo, a direct effect of GnRHa on testicular testosterone production was demonstrated in hypophysectomized animals, although this effect was temperature-dependent, requiring the frog to be maintained at a high temperature (24° C). No effect of GnRHa was detectable in frogs kept at a low temperature (4°C).