title: Modulation of fear/anxiety responses, but not food intake, following α-adrenoceptor agonist microinjections in the nucleus accumbens shell of free-feeding rats.
abstract: This study investigated the effect of α-adrenoceptor agonists microinjected into the shell region of the accumbens nucleus (AcbSh) on feeding and anxiety-related behaviors in free-feeding rats. Male Wistar rats with a chronically implanted cannula into the AcbSh were unilaterally microinjected with either clonidine (CLON, α(2)-adrenoceptor agonist) or phenylephrine (PHEN, α(1)-adrenoceptor agonist) at the doses of 6 and 20 nmol and submitted to the elevated plus-maze (EPM), a pre-clinical test of anxiety. Immediately after the EPM test, the animals underwent food intake evaluation for 30 min. The data showed that rats microinjected with CLON (20 nmol/0.2 μl) into the AcbSh exhibited increased %Open arm time, which is compatible with an anxiolytic-like effect. The CLON-induced anxiolysis was corroborated by increased head-dipping and decreased stretched-attend posture, two ethologically derived behaviors which are fear/anxiety-motivated. The animal's locomotor activity was not changed by 20 nmol CLON microinjection into the AcbSh. However, neither dose of PHEN microinjected into the AcbSh was able to alter either the spatial-temporal or ethological variables representative of fear/anxiety and locomotion. Food intake was not altered by any dose of CLON and PHEN microinjected into the AcbSh, but the 20 nmol CLON microinjection induced increased motor activity in the feeding test. The data suggests that noradrenergic projections to the AcbSh may underlie fear/anxiety modulation through α(2)-adrenoceptor in the AcbSh, while feeding behavior was unaffected by noradrenergic modulation in the AcbSh of free-feeding rats. This article is part of a Special Issue entitled 'Anxiety and Depression'.
authors.affiliation: Department of Physiological Sciences, Centre of Biological Sciences, Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil. larissakochen@gmail.com
authors.forename: Larissa
authors.initials: L
authors.lastname: Kochenborger
authors.forename: Débora
authors.initials: D
authors.lastname: Zanatta
authors.forename: Luigi Marins
authors.initials: LM
authors.lastname: Berretta
authors.forename: Ana Paula Fraga
authors.initials: AP
authors.lastname: Lopes
authors.forename: Bruna Luiza
authors.initials: BL
authors.lastname: Wunderlich
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Januário
authors.forename: José Marino
authors.initials: JM
authors.lastname: Neto
authors.forename: Mariana Graciela
authors.initials: MG
authors.lastname: Terenzi
authors.forename: Marta Aparecida
authors.initials: MA
authors.lastname: Paschoalini
authors.forename: Moacir Serralvo
authors.initials: MS
authors.lastname: Faria
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D003000:Clonidine / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005239:Fear / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008845:Microinjections; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000316:Adrenergic alpha-Agonists; D010656:Phenylephrine; D003000:Clonidine