Role of the Histaminergic System in the Inhibitory Effect of Melatonin on Broiler Chicken Feed Intake

Prior investigations have postulated that melatonin, a prominent hormone produced by the pineal gland, can reduce animal food consumption. This study was designed to evaluate the involvement of central histamine H1 and H2 receptors in regulating melatonin-induced feeding behavior among broiler chickens. The research comprised three distinct experiments: In experiment 1, the four groups of chickens received intracerebroventricular (ICV) injections of the control solution, 2.5, 5, and 10 nmol of melatonin. In experiment 2, ICV administration of drugs in four groups of chickens was conducted as control solution, chlorpheniramine (histamine H1 receptor antagonist, 64 nmol), melatonin (10 nmol) and chlorpheniramine + melatonin. In experiment 3, birds received ICV injections with the same procedure as experiment 2, except they were injected with famotidine (histamine H2 receptor antagonist, 148 nmol), instead of chlorpheniramine. Cumulative feed intake measurements were obtained during the 3 h following the injections. The administration of melatonin (10 nmol) led to a notable reduction in feed intake (P < 0.05). Pre-injection of chlorpheniramine (64 nmol) mitigated the inhibitory impact of melatonin on feed intake (P < 0.05). In contrast, pre-injection of famotidine (148 nmol) failed to exert any significant influence on melatonin-induced feeding behavior. In conclusion, the findings suggest the presence of an interaction between melatonin and the central histaminergic system, mediated through H1 receptors, in the modulation of feed intake in broiler chickens.