ABSTRACT
Prolactin in Nonmammalian Vertebrates Prolactin is also present in teleosts, amphibians, reptiles, and birds. In amphibians, PRL accelerates larval growth and blocks metamorphosis. It appears to be osmoregulatory in fishes and amphibians, where it is also, like PTH, a hypercalcemic factor. North American migratory birds exposed to a long day cycle release PRL, which induces premigratory fattening. As in mammals, TRH and VIP stimulate PRL release in birds. PRL stimulates brooding behavior (egg incubation) in chickens, and they stop laying eggs. When DA agonists are administered, egg-laying resumes (Ch. 72).
