Effects of exogenous prolactin on ovarian growth and fattening in the redheaded bunting, Emberiza bruniceps

Abstract

Subcutaneous daily injections of ovine prolactin (PRL) inhibit photoperiodic induction of gonads and fattening in the female redheaded bunting (Emberiza bruniceps). However, birds respond to the same photoperiod (15L:9D) after withdrawal of the exogenous PRL. Further, PRL injections given in late hours during the subjective days induce ovarian regression in the photostimulated females. The results suggest that the PRL has an inhibitory role on gonadal photoperiodic responses in redheaded buntings, and extend our understanding of the regulatory function of PRL in migratory birds. © 1983.