The Effect of Histaminergic System on Nociceptin/Orphanin FQ Induced Food Intake in Chicken

The aim of this study was to investigate effects of intracerebroventricular injection of alpha-Fluoromethylhistidine (alpha-FMH; histidine decarboxylase inhibitor), Chlorpheniramine (histamine H-1 receptor antagonist), Famotidine (histamine H-2 receptor antagonist) and Thioperamide (histamine H-3 receptor antagonist) on Nociceptin/Orphanin FQ-induced feed intake response in chicken. A hundred and twenty-eight broiler cockerels (four groups eight replicate), were cannula surgically implanted into the lateral ventricle, used in four separate experiments. Experiment 1, cockerels injected intracerebroventricularly with alpha-FMH (250 nmol) followed by Nociceptin/Orphanin FQ (16 nmol). In experiment 2, chickens received Chlorpheniramine (300 nmol) prior to injection of Nociceptin/Orphanin FQ (16 nmol). In experiment 3, birds were administered with Nociceptin/Orphanin FQ (16 nmol) after Famotidine (82 nmol) injection. In experiment 4, broilers were injected with thioperamide (300 nmol) followed by Nociceptin/Orphanin FQ (16 nmol). Cumulative food intake was measured until 3 h post-injection. According to the results, a significantly increase was observed after injection of Nociceptin/Orphanin on food intake and this effect was amplified by pre-administration of alpha-FMH and Chlorpheniramine in broilers (p < 0.05). Moreover, famotidine had no effect on hyperphagia induced by Nociceptin/Orphanin FQ in chicken (p > 0.05). Also, pre-administration of thioperamide significantly attenuated Nociceptin/Orphanin FQ-induced hyperphagia (p < 0.05). These results suggest that, Nociceptin/Orphanin FQ-induced hyperphagia is mediated by histaminergic system via H-1 and H-3 receptors in broiler chickens.