Role of gonadal feedback in annual reproduction of the weaver bird: Interaction with photoperiod

Abstract

Involvement of gonadal steroids in the annual reproduction of the weaver bird has been demonstrated by castration experiments. Castration renders the pituitary acyclic, as observed by LH-dependent yellow nuptial plumage, indicating the role of gonads in seasonal decline of pituitary activity. It was also evident from the results of castration performed at different months that sensitivity of the hypothalamo-hypophyseal system to negative feed-back of testicular hormones changes with the phase of the reproductive cycle. The initiation of pituitary activity in this bird seems to be direct effect of photostimulation and not a consequence of altered sensitivity of the pituitary or the hypothalamus to gonadal steroids. Gonadal steroids appear to interfere with/alter the photoresponse of this bird. The annual reproduction in the weaver bird seems to be a result of interaction between steroidal feedback and the day length.