title: Modulatory effects of the basolateral amygdala α2-adrenoceptors on nicotine-induced anxiogenic-like behaviours of rats in the elevated plus maze.
abstract: The present study was designed to clarify whether α2-adrenoceptors of the basolateral amygdala (BLA) are involved in nicotine-induced anxiogenic-like behaviours. Adult male Wistar rats were bilaterally cannulated in the BLA and anxiety-like behaviours were assessed in an elevated plus maze (EPM) task. Systemic intraperitoneal (i.p.) administration of nicotine (0.3, 0.5 and 0.7 mg/kg) dose-dependently decreased open arm time (%OAT) and open arm entry (%OAE), indicating the anxiogenic-like effect of nicotine. The activation of the BLA α2-adrenoceptors by the injection of α2-receptor agonist, clonidine (0.1, 0.3 and 0.5 μg/rat) into the BLA (intra-BLA) reversed nicotine-induced anxiogenic-like behaviours. It is important to note that intra-BLA injection of a higher dose of clonidine (0.5 μg/rat) by itself increased %OAT, but not %OAE which showed an anxiolytic effect of the agonist. On the other hand, intra-BLA injection of different doses of α2-adrenoceptor antagonist, yohimbine (1, 3 and 5 μg/rat) in combination with an ineffective dose of nicotine (0.3 mg/kg) decreased %OAT and %OAE, suggesting a potentiative effect of the antagonist on nicotine response. In addition, intra-BLA injection of the same doses of yohimbine did not alter %OAT and %OAE. Interestingly, intra-BLA injection of yohimbine (0.5 and 1 μg/rat) significantly reversed the inhibitory effect of clonidine on nicotine-induced anxiogenic-like behaviours. It should be considered that the drug treatments had no effect on locomotor activity in all experiments. Taken together, it can be concluded that nicotine produces anxiogenic-like behaviours which may be mediated through the BLA α2-adrenoceptor mechanism.
authors.affiliation: Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamideh
authors.initials: H
authors.lastname: Bashiri
authors.affiliation: Department of Animal Biology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran.
authors.forename: Ameneh
authors.initials: A
authors.lastname: Rezayof
authors.affiliation: Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mousa
authors.initials: M
authors.lastname: Sahebgharani
authors.affiliation: Department of Pathology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Tavangar
authors.affiliation: Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran; School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran; Institute of Cognitive Science Studies (ICSS), Tehran, Iran. Electronic address: zarinmr@ams.ac.ir.
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Zarrindast
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001007:Anxiety / Q000139:chemically induced / Q000378:metabolism*; D066272:Basolateral Nuclear Complex / Q000187:drug effects* / Q000378:metabolism*; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000008:administration & dosage*; D017208:Rats, Wistar; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: C547769:Adra2a protein, mouse; D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D018722:Nicotinic Agonists; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D009538:Nicotine; D003000:Clonidine
keywords: Anxiety-like behaviours; Basolateral amygdala; Clonidine; Nicotine; Rat(s); Yohimbine