title: Methylamine induced hypophagia is mediated via dopamine D1 and D2 receptors in neonatal meat chicks.
abstract: Recently, methylamine has been found as an endogenous amine, which is controlling food intake in mammals. However, there is no evidence about the effect of methylamine on feeding behavior in poultry. So, the present study was designed to evaluate the effect of intracerebroventricular (ICV) injection of methylamine and involvement of central methylamine/dopaminergic systems on feeding behavior in neonatal meat type chicks. In experiment 1, chicks were ICV injected with different doses of methylamine (0.48, 0.96, 1.44, 1.92 and 2.40 μmol). In experiment 2, chicks received a dose of either the control solution, 2.40 μmol methylamine, 125 nmol L-DOPA (dopamine precursor) or a combination of methylamine plus L-DOPA. Experiments 3-7 were similar to experiment 2 except that 150 nmol 6-OHDA (dopamine synthase inhibitor), 5 nmol SCH23390 (D1 receptor antagonist), 5 nmol AMI-193 (D2 receptor antagonist), 6.4 nmol NGB2904 (D3 receptor antagonist) and 6 nmol L-741, 742 (D4 receptor antagonist) were used instead of 125 nmol L-DOPA, respectively. Cumulative food intake was determined until 2 h post-injection. According to the results, methylamine significantly decreased food intake in a dose dependent manner (p < 0.05). The inhibitory effect of methylamine on food intake was significantly attenuated by 6-OHDA, SCH23390 and AMI-193 (P < 0.05), but NGB2904 and L-741, 742 had no effect on food intake induced by methylamine. In addition, hypophagic effect of methylamine significantly amplified by L-DOPA (P < 0.05). These results suggest that methylamine decrease food intake and there is an interaction between methylamine and dopaminergic system via D1 and D2 receptors in chickens.
authors.affiliation: Section of Physiology, Department of Basic Sciences, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Mansour
authors.initials: M
authors.lastname: Mahzouni
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, 14155-6453, Iran. zendedel@ut.ac.ir.
authors.forename: Morteza
authors.initials: M
authors.lastname: Zendehdel
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, 14155-6453, Iran.
authors.forename: Vahab
authors.initials: V
authors.lastname: Babapour
authors.affiliation: Section of Poultry, Department of Clinical Sciences, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Charkhkar
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002645:Chickens / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D005247:Feeding Behavior / Q000187:drug effects*; D057967:Infusions, Intraventricular; D008744:Methylamines / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism*
chemical_list: D018492:Dopamine Antagonists; D008744:Methylamines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C027451:methylamine
keywords: Chick; Dopamine; Food intake; Methylamine