Topiramate Reduces Basal Anxiety and Relieves Ethanol Withdrawal-Induced Anxious Behaviors in Male Rats
Anxiety disorders are associated with increased impairments in psychosocial functioning, work productivity and health-related quality of life. In addition, anxiety is a common symptom of ethanol withdrawal and it strongly contributes to relapse. Benzodiazepines are frequently prescribed for relief of anxiety and ethanol withdrawal symptoms but considerable side effects, such sedation, tolerance and dependence, are observed during treatment. Therefore, better drugs are needed for the treatment of anxiety states. The purpose of this study was to investigate whether topiramate would reduce basal levels of anxiety and ethanol-withdrawn induced anxiety in male rats; the elevated plus maze (EPM) was used as an animal model of anxiety. In Experiment 1, topiramate (0, 10, and 40 mg/kg, i.g.) and diazepam (1 mg/kg, i.p.) was acutely and repeatedly administered to naive rats. In Experiments 2 and 3, topiramate (0 or 40 mg/kg, i.g.) was acutely and chronically administered in early (72 hr after ethanol removal) and protracted (21 days after ethanol removal) ethanol-withdrawn rats, respectively. Acute and repeated topiramate treatment induced anxiolytic-like effects in naive rats. Early ethanol withdrawal increased anxiety, and acute topiramate administration counteracted the anxiogenic-like effects of ethanol removal. Protracted withdrawal did not produce lasting changes in anxiety but topiramate was equally effective at reducing anxiety in ethanol-withdrawn and control animals. Importantly, no signs of tolerance to the anxiolytic effects of topiramate were observed. In conclusion, these data support a role for topiramate in the treatment of basal levels of anxiety and ethanol withdrawal-induced anxiety.