Intracerebroventricular Injection of the Glutamatergic Receptors Antagonist Affects N/OFQ-Induced Hyperphagia in Neonatal Broilers: Role of NMDA and AMPA Receptors

Abstract

This study was designed to determine possible interaction of the central nociceptin/orphanin FQ (N/OFQ) and glutamatergic system on feeding behavior in neonatal broilers chicken. In experiment 1, 3-h food deprived (FD3) chicks received intracerebroventricular (ICV) injection of (i) control solution, (ii) N/OFQ (16 nmol), (iii) MK-801 (NMDA [N-methyl-d-aspartate-type glutamate] receptor antagonist, 15 nmol) and (iv) N/OFQ + MK-801. Experiments 2–7 were similar to experiment 1, except chicken ICV injected with CNQX (AMPA [α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid] receptor antagonist, 390 nmol), UBP-302 (kainate receptor antagonist, 390 nmol), AIDA (mGluR1 antagonist, 2 nmol), LY341495 (mGluR2 antagonist, 150 nmol), UBP1112 (mGluR3 antagonist, 2 nmol) and Glutamate (300 nmol) instead of MK-801. Then the cumulative food intake measured until 120 min post injection. According to the results, ICV injection of N/OFQ significantly increased food intake (P < 0.05). Co-administration of the N/OFQ + MK-801 significantly amplified N/OFQ-induced hyperphagia in neonatal broilers (P < 0.05). Injection of the N/OFQ + CNQX significantly increased hyperphagic effect of the CNQX in neonatal meat-type chicken (P < 0.05). Co-injection of the N/OFQ + glutamate significantly decreased N/OFQ-induced hyperphagia in neonatal meat type chicken (P < 0.05). These results suggested interconnection between central N/OFQ and glutamatergic systems on feeding behavior mediates via NMDA and AMPA receptors in neonatal broilers.