Intracerebroventricular administration of mouse leptin does not reduce food intake in the chicken

Recently, it has been suggested that leptin plays an important role in regulation of food intake and metabolism in rats and mice, however, the effect of central administration of leptin on food intake in chicks has not been reported. We have investigated the anorexigenic effect of leptin administered by intracerebroventricular (i.c.v.) injection in chicks using mouse leptin, which shows 97% homology to chicken leptin. Three experiments were conducted. After being deprived of food for 3 h, male broiler chicks were administered leptin by i.c.v. injection at dose levels of 0, 0.2, 1.0 and 5.0 microg (Experiment 1) or 0, 2.5 and 5.0 microg (Experiment 2). The birds were allowed free access to the diet for 2 h (Experiment 1) and 24 h (Experiment 2) after treatment. Male Single Comb White Leghorn chicks were used in Experiment 3 and were treated in the same manner as in Experiment 1. In all experiments, central administration of mouse leptin did not influence food intake in the time periods examined. It appears that either mouse leptin does not bind to the chicken leptin receptor or in the chicken brain the leptin receptor may be absent.