Avicenna Journal of Pharmaceutical Research

Background: This study aimed to investigate the potential antidepressive-like effect of the aqueous extract of Mentha piperita (peppermint) leaves using two predictive models of depression, namely, forced swimming test (FST) and tail suspension test (TST), in male Wistar albino mice. For this purpose, after weighting, coding, and classifying the mice, they were grouped (n=6) as test (175 mg/kg, 350 mg/kg, and 700 mg/kg M. piperita aqueous extract; i.p.) and control (20 mg/kg fluoxetine and 30 mg/kg imipramine; i.p.) groups and the blank group (normal saline; i.p.) and received medication or extract for 28 days before the tests.

Results: All doses of the aqueous peppermint extract compared to the control group markedly reduced the immobility duration in both FST and TST when administered intraperitoneally for 28 days. In addition, our results demonstrated that 350 mg/kg and 700 mg/kg of the peppermint aqueous extract increased swimming time significantly (P<0.001) without any significant change in climbing (struggling) duration.

Conclusion: The results of this study suggest that the aqueous extract of Mentha piperita leaves has anti-depressant-like activity in the animal models of depression that might be a cause of increasing central serotonergic activity. However, more studies are required to determine the exact mechanisms of action.