The aim of this study was to investigate effects of intracerebroventricular injection of a-Fluoromethylhistidine (a-FMH; histidine decarboxylase inhibitor),Chlorpheniramine (histamine H1 receptor antagonist), Famotidine (histamine H2 receptor antagonist) and Thioperamide (histamine H3 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 a-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 wasmeasured until 3 h post-injection.According to the results, a significantly increase was observed after injection of Nociceptin/Orphanin on food intake and this effectwas amplified by pre-administration of a-FMHandChlorpheniramine 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 H1 and H3 receptors in broiler chickens. DOI: 10.1007/s10989-014-9445-5

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