SUMMARYThe purpose of this study was to characterize the putative anxiolytic-like effects of the 70% ethanol extract of Portulaca oleracea (EPO) using an elevated plus maze (EPM) in mice. The EPO was orally administered at 50, 100, 200 or 400 mg/kg to ICR mice, 1 h before the behavioral evaluation in the EPM, respectively. Control mice were treated with an equal volume of 10% tween 80, and positive control mice with diazepam (1 mg/kg). Single treatments of the EPO significantly increased the percentage of time spent and arm entries into the open arms of the EPM versus controls (P < 0.05). Moreover, there were no changes in the locomotor activity and myorelaxant effects in any group compared with the saline controls. In addition, the anxiolyticlike effects of the EPO were blocked by flumazenil (10 mg/kg, i.p), a GABA receptor antagonist. These results indicate that P. oleracea is an effective anxiolytic agent, and suggest that the anxiolytic-like effects of P. oleracea is mediated via the GABAergic nervous system.