Experimental anxiety and antiepileptics: the effects of valproate and vigabatrin in the mirrored chamber test

Abstract

The potential anxiolytic-like effects of valproate (VPA; 200, 300 and 400 mg/kg i.p.) and vigabatrin (GVG; 150, 300 and 450 mg/kg i.p.) were evaluated in an experimental model of anxiety in mice. The mirrored chamber test was the model selected. In this study, anxiogenic-like behavior was induced by pretreatment with m-chlorophenylpiperazine hydrochloride (m-CPP; 1 mg/kg i.p.). For comparative purposes, the effects of an established reference anxiolytic, lorazepam (LOR; 0.025, 0.05 and 0.10 mg/kg i.p.) were also evaluated. Results showed that 2 weeks of repeated treatment with 200, 300 and 400 mg/kg of VPA or, to a lesser extent, 300 and 450 mg/kg i.p. of GVG, antagonized the anxiogenic effects of m-CPP. VPA induced behavioral changes very similar to those produced by lorazepam, i.e., a decrease in the latency time to enter the mirrored chamber and an increase in the time spent in the mirrored chamber. The anxiolytic-like potency of GVG was lower than that of VPA in this test. In conclusion, these data provide additional evidence for the anxiolytic-like effects of VPA and substantiate its role in the treatment of anxiety disorders and in the withdrawal state of ethanol or sedative-hypnotics.