Chronic blockade of cannabinoid CB2 receptors induces anxiolytic-like actions associated with alterations in GABAA receptors

BACKGROUND AND PURPOSE: The aim of this study was to explore the effects of CB2 receptor agonist and antagonist in the regulation of anxiety-like behaviours. EXPERIMENTAL APPROACHES: Effects of acute and chronic treatment with the CB2 receptor agonist JWH133 and CB2 receptor antagonist AM630 were evaluated in the light-dark box (LDB) and elevated plus maze (EPM) tests in Swiss ICR mice. CB2 receptor, GABAAa2 and GABAAg2 gene and protein expression in the cortex and amygdala of mice chronically treated with JWH133 or AM630 were examined by RT-PCR and Western blot. Effects of chronic AM630 treatment were evaluated in spontaneously anxious DBA/2 mice in LDB....