title: Modulation of opioid-induced feeding behavior by endogenous nitric oxide in neonatal layer-type chicks.
abstract: The current study was designed to evaluate the effects of central administration of L-arginine (The precursor of nitric oxide), N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase inhibitor, selective opioid receptor agonists and involvement of central nitrergic/opioidergic systems on feeding behavior in neonatal layer-type chicks. The results of this study showed that the intracerebroventricular (ICV) injection of L-arginine (400 and 800 nmol) significantly decreased food intake (P < 0.001) but the injection of 200 nmol L-arginine had no effect on cumulative food intake in FD3 chickens (P > 0.05). The ICV injection of L-NAME (200 and 400 nmol) increased food intake (P < 0.001) but 100 nmol of L-NAME had no significant effect (P > 0.05). On the other hand, the co-injection of 100 nmol L-NAME significantly attenuated the anorexigenic effect of 800 nmol L-arginine (P < 0.001). Moreover, the food intake of chicks was significantly decreased by ICV injection of DAMGO (μ-opioid receptor agonist, 125 pmol) (P < 0.001) while both DPDPE (δ-opioid receptor agonist, 40 pmol) and U-50488H (κ-opioid receptor agonist, 30 nmol) significantly stimulated food intake (P < 0.001). In addition, the hypophagic effect of DAMGO was significantly amplified by administration of L-arginine (P < 0.001) while the administration of L-NAME attenuated the hypophagic effect of DAMGO (P < 0.001). In contrast, co-injection of L-arginine or L-NAME with DPDPE had no effect on the hyperphagia induced by DPDPE as well as the hyperphagic effect of U-50488H on food intake was not affected by concurrent injection of L-arginine or L-NAME (P > 0.05). These results suggest that nitrergic and opioidergic systems have an important role on feeding behavior in the CNS of neonatal layer-type chicks and it seems that interaction between them is mediated by μ-opioid receptor.
authors: Department of Physiology, Faculty of Veterinary Medicine, University of Tehran, PO Box: 14155-6453, Tehran, Iran.
authors: Samad
authors: S
authors: Alimohammadi
authors: Morteza
authors: M
authors: Zendehdel
authors: Vahab
authors: V
authors: Babapour
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology; D002645:Chickens / Q000502:physiology*; D004435:Eating / Q000187:drug effects*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000008:administration & dosage / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D005247:Feeding Behavior / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology*; D009569:Nitric Oxide / Q000494:pharmacology*; D017450:Receptors, Opioid, mu / Q000378:metabolism
chemical_list: D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester