Time course and response specificity of prolactin-induced hyperphagia in ring doves.

Abstract

Intracranial injections of prolactin (PRL) have been previously shown to elevate food and water intake in ring doves. In an attempt to further characterize these PRL-induced behavioral responses and the time course of PRL action, food and/or water intake were measured as frequent intervals in male doves given a single intracerebroventricular (ICV) injection of ovine PRL (44 pmoles) or vehicle under food deprivation, water deprivation, or nondeprivation conditions. PRL increased food consumption by 35-50% over baseline levels in water deprived and nondeprived doves, although response latencies (10 hr) and durations (greater than 24 hr) were considerably longer than those reported for other orexigenic peptides. Behavioral observations of nondeprived doves further revealed that PRL significantly increased total time spent feeding and average feeding bout duration. In contrast to this pattern, water intake remained unchanged in food deprived doves and was only marginally increased in nondeprived doves following PRL treatment. Collectively, these results suggest that PRL promotes a selective and long-lasting hyperphagia which may in turn augment drinking activity.