The microinjection of AMPA receptor antagonist into the accumbens shell, but not into the accumbens core, induces anxiolysis in an animal model of anxiety.
This study investigated the effect of the AMPA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) microinjected into the core and shell sub-regions of the accumbens nucleus (Acb), on the level of fear/anxiety and emotional learning, in female rats submitted to the elevated plus-maze (EPM), an animal model of anxiety. Bilateral microinjections of DNQX (330 and 660 ng) into the Acb shell (AP, +1.08 to +2.16) induced an anxiolytic-like effect in relation to rats microinjected with vehicle, since there was an increased percentage of entries in the open arms of the maze. The 660 ng DNQX microinjection into the Acb shell also increased the percentage of entries into the open arms in relation to 660 ng DNQX microinjection into the Acb core. Prior DNQX microinjections in both core and shell sub-regions of the Acb failed to impair the emotional learning, since the animals exhibited an increase of the open arm avoidance on EPM Trial 2 in relation to EPM trial 1. DNQX microinjections into both sub-regions of the Acb did not change the number of entries into the enclosed arms, either in the EPM Trial 1 or in the EPM Trial 2, which indicates an absence of drug-induced locomotor impairment. Similarly, DNQX microinjections into both sub-regions of the Acb failed to alter the total arm entries, rearing, grooming and head-dipping frequency. The anxiolytic-like effect induced by DNQX suggests that the AMPA receptor in the Acb shell, but not in the Acb core, may underlie anxiety regulation in the EPM.
Department of Physiological Sciences, Centre of Biological Sciences, Federal University of Santa Catarina, 88.040-900 Florianópolis, SC, Brazil.
Isabel Cristina
IC
da Cunha
Ana Paula Fraga
AP
Lopes
Sergio Murilo
SM
Steffens
Adriana
A
Ferraz
Juliano Cordova
JC
Vargas
Thereza Christina Monteiro
TC
de Lima
José
J
Marino Neto
Marta Aparecida
MA
Paschoalini
Moacir Serralvo
MS
Faria
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000139:chemically induced / Q000378:metabolism*; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology*; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008845:Microinjections; D009714:Nucleus Accumbens / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D011810:Quinoxalines / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D018091:Receptors, AMPA; C056723:FG 9041