Central Opioidergic and Adrenergic systems Mediates Food Intake via α1, α2 and β2 Receptors in Neonatal Layer-Type Chicken

Abstract

The aim of the current study was to determine possible interaction of central Opioidergic and Adrenergic systems on food intake regulation in neonatal layer-type chicken. In experiment 1, chicken ICV injected with control solution, DAMGO (µopioid receptors agonist, 125 pmol), parazosin (α1 receptor antagonist, 10 nmol) and DAMGO + parazosin. In experiment 2, control solution, DAMGO (125 pmol), yohimbine (α2 receptor antagonist, 13 nmol) and DAMGO + yohimbine were ICV injected. In experiment 3, FD3 birds ICV injected with control solution, DAMGO (125 pmol), metoprolol (β1 receptor antagonist, 24 nmol) and DAMGO + metoprolol. In experiment 4, FD3 chicks received ICV injection of control solution, DAMGO (125 pmol), ICI 118,551 (β2 receptor antagonist, 5 nmol) and DAMGO + ICI 118,551. Experiments 5–8 were similar to experiments 1–4, except chicken injected with DPDPE (δ opioid receptors agonist, 40 nmol) instead of DAMGO. Experiments 9–12 were similar to experiments 1–4, except chicken injected with U-50488H (κ opioid receptors agonist, 30 nmol) instead of DAMGO. Then, cumulative food intake was recorded at 30, 60 and 120 min after injection. According to the results, ICV injection of the DAMGO significantly decreased food intake while DPDPE and U-50488H significantly increased food intake in neonatal layer type chicken (P < 0.05). Co-injection of the DAMGO + ICI 118,551 decreased DAMGO-induced hypophagia (P < 0.05). Also, co-injection of the DPDPE + parazosin diminished hyperphagic effect of the DPDPE (P < 0.05). In addition, co-injection of the U-50488H + yohimbine diminished U-50488H-induced hyperphagia (P < 0.05). These results suggested there are interconnection between adrenergic and opioidergic systems on central food intake regulation which mediates via α1, α2 and β2 receptors in neonatal layer-type chicken.