Effects of piscine and mammalian gonadotropins on gametogenesis in the catfish, Heteropneustes fossilis (bloch)

Abstract

Salmon (SG-G100) and mammalian (ovine FSH and LH) gonadotropins were tested for their gonadotropic activity in the hypophysectomized catfish, Heteropmeustes fossilis, by evaluating induction of spermatogenesis and spermiation in the male, as well as vitellogenesis, ovarian maintenance, and ovulation in the female. In the male, SG-G100 was 10 times more potent than LH in reinitiating and restoring spermatogenesis; FSH was virtually ineffective, even at high dose levels. Spermiation was induced only by SG-G100. Vitellogenesis was induced by SG-G100 and carp pituitary Sephadex G100 fraction II, whereas LH and carp pituitary Sephadex G100 fractions I and III were inefective at comparable dose levels. SG-G100 was 5 and 2.5 times more potent than LH in ovarian maintenance and ovulation responses, respectively; FSH was only marginally effective even at high dose levels. Our data provide corroborative evidence for the tentative view that, in teleosts, only a single gonadotropin (physiologically similar to mammalian LH) may regulate the whole maturational phenomenon.