Effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in hypophysectomized catfish, <i>Heteropneustes fossilis</i> (Bloch)

Abstract

Abstract Experiments were conducted to evaluate the effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in three‐day hypophysectomized gravid catfish. Of the hypophysial hormones tested (FSH, LH, LtH, STH, TSH, ACTH, and oxytocin), at various dose levels, LH alone consistently induced ovulation and spawning of eggs; administration of 5 mg/fish evoked the best response. The weak response obtained with FSH, STH, or TSH was not due to LH contamination. HCG at a dose level of 100 IU/fish induced ovulation and spawning, whereas in the case of PMS, doses of 250 IU/fish and above were equally effective. None of the gonadal hormones tested (estradiol, testosterone, and progesterone) evoked ovulation or spawning. All the adrenal corticosteroids tested (hydrocortisone, cortisone, and DOCA) proved to be powerful ovulating agents, DOCA (5 mg/fish) being the most effective. These findings indicate that in the catfish, LH and HCG as well as adrenal corticosteroids are effective in inducing ovulation and spawning in three‐day hypophysectomized gravid catfish. The possible mechanisms involved are discussed.