Specificity to gonadotropins in the response of in vitro estrogen secretion by fish ovaries

Gonadotropin preparations from three classes of tetrapods (amphibian, avian, and mammalian) and a chondrosteian and teleost fish were used to investigate the species specificity and hormonal (FSH/LH) specificity of in vitro steroid (estradiol-17 beta) production by the teleost ovary. Results for ovaries from one species of gobiid, Gillichthys mirabilis, and two cichlids, Cichlasoma citrinellum and Sarotherodon mossambicus, revealed a general lack of species specificity in the response to tetrapod gonadotropins, but the piscine, especially sturgeon, gonadotropins were much more potent than any of the tetrapod hormones. All three species of teleost ovaries responded to both types of tetrapod gonadotropins (FSH and LH), but the extent of hormonal specificity was variable. The gobiid ovary showed the highest LH specificity (potencies of FSHs = 7-14% of LH); in the two cichlids the potency of FSHs ranged from 11 to 100% of the respective LHs. In general, the specificity of the ovarian steroidogenic response to gonadotropins parallels that observed for testosterone secretion in the males of the same three fish, but the differential actions of the tetrapod hormones (both species and hormonal specificity) are more exaggerated for the testes.