Mechanism of Effect Opioid Central Food Intake Regulation in Ad LibitumFedNeonatalLayer-Type Chicken

Inroduction & Opioidergic system has crucial role on central regulation of food intake in mammals and birds. This study was designed to investigate role of opioidergic system on opioid-induced feeding behavior in 3-h food-deprived (FD3) neonatal layer-type chicks.
Material and 144 chickens allocated into3 experiments, each with four treatment groups. In Experiment 1, birds were ICV injected with D-Ala2–NMe-Phe4-Glyol5-enkephalin (DAMGO, µ-opioid receptor agonist) (125, 250 and 500pmol). In Experiment 2, chickens were ICV treated with D-Pen2,5Enkephalin,D-Pen2,D-Pen5Enkephalin (DPDPE, δ-opioid receptor agonist) (20, 40 and 80pmol). In Experiment 3, the effect of ICV injection of U-50488H -, κ opioid receptor agonist (10, 20 and 30nmol) was investigated in chicks.Cumulative food intake recorded until 3-h post injection.
According to the results, ICV injection of µ-opioid receptor agonist significantly diminished food intake (P≤0.05). Also, injection of δ and κ-opioid receptors agonist significantly increased food intake (P≤0.05). ICV injection of DAMGO significantly decreased food intake whereas DPDPE and U-50488H increased food intake (P≤0.05).
These results suggest that central opioidergic system has important role on feeding behavior.