Aim: The purpose of the present study was to evaluate the anxiolytic effects of the aqueous extract of Lemon verbena on rats. Materials and Methods: In this study, aqueous extract of Lemon verbena leaves was prepared, and then male Wistar rats (200-230 g) were divided randomly into six experimental groups. Each group received a single intraperitoneal (IP) injection of saline, aqueous extract of Lemon verbena (10 mg/kg, 100 mg/kg, 500 mg/kg, 1,000 mg/kg)or diazepam, respectively. The level of anxiety was asserted by an elevated plus maze (EPM) 20 min after treatment. Statistical Analysis Used: Results were analyzed by one-way analysis of variance (ANOVA) and Tukey's post-hoc test. The results were expressed as mean ± standard error of mean (SEM). The differences were considered significant at P < 0.05. Results: The results of this study showed that there was a significant difference in the number of entrances into the open arms, spent time in the open arms and number of total entrances into the open and closed arms of the EPM between control, diazepam and extract-receiving groups (10 mg/kg, 100 mg/kg, 500 mg/kg, 1,000 mg/kg) and control. The numbers of entrances into the open arms, spent time in the open arms in extract receiving groups were significantly less than control group. Conclusion: These results indicated that acute administration of aqueous extract of Lemon verbena (≥10 mg/kg) increased anxiety-like behavior in rats in the EPM.
Key words: Anxiety, elevated plus maze, rat, vervain