Effects of chicken and mammalian gonadotropin-releasing hormones (GnRH) on in vivo pituitary gonadotropin release in amphibians and reptiles.

The ability of mammalian and chicken gonadotropin-releasing hormones (GnRH) and their agonistic analogs to stimulate in vivo gonadotropin release were tested in a frog (Rana catesbeiana), snake (Naja naja), and turtle (Sternotherus odoratus). In the frog, chicken and mammalian GnRH were equipotent in stimulating the release of FSH and LH. Attendant increases in plasma androgen and the occurrence of spermiation confirmed the release of biologically active gonadotropin. Neither of the GnRH preparations or their agonists produced significant changes in plasma hormones in either of the reptiles. In light of comparable data for the actions of these GnRH preparations in mammals and birds, it appears that species specificity in the response to different GnRHs does not correlate well with the nature of the homologous hypothalamic GnRH molecule.