title: Role of intra-hippocampal orexin 1 and orexin 2 receptors in conditioned place preference induced by chemical stimulation of the lateral hypothalamus.
abstract: Evidence from animal models suggests a role for orexinergic system in reward processing and drug addiction. The lateral hypothalamus (LH) orexin neurons send projections to the dorsal hippocampus (CA1 region) which plays a pivotal role in reward processes. Moreover, it has been shown that orexin containing terminals and orexin receptors are distributed in the hippocampal formation. In this study, we assessed the role of orexin 1 (OX1r) and orexin2 (OX2r) receptors in the CA1 on the development of LH stimulation-induced conditioned place preference (CPP). Animals weighing 230-280 g were unilaterally implanted by two separate cannulae into the LH and CA1. The CPP paradigm was done; SB334867 and TCSOX229, as selective OX1r and OX2r antagonists (1, 3, 10 and 30 nM/0.5 μl DMSO) administrated into the CA1 prior to intra-LH carbachol microinjection (250 nM; the most effective dose) during the 3-days conditioning phase, respectively. Conditioning scores and locomotor activities were recorded by Ethovision software on the test day. The results showed that the administration of OX1r and OX2r antagonists into the CA1 attenuated the development of CPP induced by chemical stimulation of the LH. However, this decrease in OX1r antagonist treated groups was more significant than that in OX2r antagonist treated animals. Our findings suggest that OX1 and OX2 receptors in the CA1 region of the hippocampus were involved in the development of CPP induced by chemical stimulation of the LH and the efficiency of OX1 receptors in this phenomenon was more considerable than OX2 receptors in rats.
authors.affiliation: Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Rashidy-Pour
authors.affiliation: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, PO Box 19615-1178, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Moradi
authors.affiliation: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, PO Box 19615-1178, Tehran, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Fatahi
authors.affiliation: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, PO Box 19615-1178, Tehran, Iran; Faculty of Dentistry, International Branch of Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Amir
authors.initials: A
authors.lastname: Haghparast
authors.affiliation: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, PO Box 19615-1178, Tehran, Iran. Electronic address: Haghparast@yahoo.com.
authors.forename: Abbas
authors.initials: A
authors.lastname: Haghparast
mesh_terms: D000818:Animals; D001583:Benzoxazoles / Q000008:administration & dosage / Q000494:pharmacology; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000008:administration & dosage / Q000494:pharmacology; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D007026:Hypothalamic Area, Lateral / Q000187:drug effects / Q000502:physiology*; D007546:Isoquinolines / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors / Q000502:physiology*; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; C572065:1-(3,4-dihydro-6,7-dimethoxy-2(1H)-isoquinolinyl)-3,3-dimethyl-2-((4-pyridinylmethyl)amino)-1-butanone; D001583:Benzoxazoles; D018679:Cholinergic Agonists; D007546:Isoquinolines; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors; D011725:Pyridines; D014508:Urea; D002217:Carbachol
keywords: CA1 region of the hippocampus; Conditioned place preference; Lateral hypothalamus; Orexin 1 receptor; Orexin 2 receptor; Reward