Interaction Between Endocannabinoid and Opioidergic Systems Regulates Food Intake in Neonatal Chicken

Abstract

Endocannabinoids and opiates have regulatory role in some physiological functions in mammals but their interaction(s) have not been studied in avian. This survey is designed to investigate interaction of these systems on feeding behavior in neonatal chickens. In experiment 1, chicken intracerebroventricular (ICV) injected with saline, DAMGO (µ-opioid receptors agonist, 125 pmol), SR141716A (CB1 receptors antagonist, 6.25 µg) and SR141716A + DAMGO. In experiment 2, saline, DAMGO, AM630 (CB2 receptors antagonist, 1.25 µg) and DAMGO + AM630. Experiments 3–6 followed the procedure similar to experiments 1 and 2, except DPDPE (δ-opioid receptors agonist, 40 pmol) and U-50488H (κ-opioid receptors agonist, 30 nmol) instead of DAMGO were used. In experiment 7, saline, Naloxone (opioid receptors antagonist, 5 µg), 2-AG (CB1 receptors agonist, 2 µg), Naloxone + 2-AG were used. Experiment 8 was similar to experiment 7, except CB65 (CB2 receptors agonist, 1.25 µg) used instead of 2-AG. Cumulative food intake was recorded until 120 min post injection. Data provided that, ICV injection of DAMGO decreased food intake and its effect amplified by CB1 and CB2 receptors antagonist (P 0.05). Hyperphagia-induced by CB1 and CB2 receptors agonist amplified by naloxone (P < 0.001). Perhaps there is interaction between endocannabinoid and opioidergic systems on appetite regulation in chicken.