Sakae Kikuyama

Hormonal control of response to and secretion of sex attractants in Japanese newts.

Hormonal control of sexual chemoattraction in the newt, Cynops pyrrhogaster, was investigated by a water preference test. Sexually inert newts injected with prolactin (PRL) and human chorionic gonadotropin (HCG) in combination preferred the water in which newts of the opposite sex had been kept, whereas saline-injected specimens did not. This indicates that PRL and HCG enhance the response of the newts to attractant(s) secreted by the opposite sex. The water in which PRL plus HCG-treated newts had been kept attracted the opposite sex more intensely than the water in which PRL-, HCG-, or saline-injected newts had been kept. In castrated males, PRL plus testosterone propionate (TP), and in ovariectomized females, PRL plus estradiol induced the secretion of substance(s) that attracted newts of the opposite sex. Removal of the abdominal gland of the cloaca in the male or the oviduct in the female attenuated the attracting activity of the water in which they were kept. Involvement of PRL and gonadal steroids in the secretion of sex attractants by the male abdominal gland and female oviduct was suggested.