title: Effects of activation and blockade of orexin A receptors in the medial preoptic area on food intake in male rats.
abstract: It has been shown that activation of type 1 orexinergic receptors (ORX1) in several parts of the hypothalamus stimulate food intake. Orexin A receptive sites for food intake exist primarily in a narrow band of the hypothalamus that is known to be involved in control of energy homeostasis. The present study aimed to investigate the role of orexin receptors in the medial preoptic area (MPOA) on food intake in rats. Twenty-four male rats weighing 200-250g were divided into three groups (n=8 in each group). Rats were cannulated using stereotaxic coordinates above the MPOA. Normal saline was microinjected into the MPOA in the control group. Another group received intra MPOA microinjection of SB334867, a selective antagonist for ORX1 receptors. In the other group, orexin A was microinjected (0.5μl of 1μmol) into the MPOA. Food intake was measured in metabolic cages. The statistical significance of differences between groups was detected by a one way ANOVA. A value of p<0.05 was considered significant. There was no significant difference in food consumption between saline and SB334867 treated groups. However, activation of the orexin receptor in the MPOA significantly increased food intake during the 2 and 8h after orexin A microinjection. Our results showed that during ad libitum access to food, activation but not blockade of the MPOA ORX1 receptor can increase food intake in a time-dependent manner. The role of these receptors in hunger and appetite stimulation requires further study.
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Abdolrahman
authors.initials: A
authors.lastname: Sarihi
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran. Electronic address: a_emam@umsha.ac.ir.
authors.forename: Amir Hossein
authors.initials: AH
authors.lastname: Emam
authors.affiliation: Department of Anatomy, Faculty of medicine, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Mohammad Hosseini
authors.initials: MH
authors.lastname: Panah
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Komaki
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Sadegh
authors.initials: S
authors.lastname: Seif
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Vafaeirad
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, P.O. Box 65 178-38678, Hamadan, Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Alaii
mesh_terms: D000818:Animals; D001583:Benzoxazoles / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists / Q000494:pharmacology*; D064446:Orexin Receptors / Q000819:agonists / Q000378:metabolism*; D000068797:Orexins / Q000494:pharmacology; D011301:Preoptic Area / Q000187:drug effects* / Q000378:metabolism; D017208:Rats, Wistar; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors; D000068797:Orexins; D014508:Urea
keywords: Food intake; Homeostasis; MPOA; Orexin A