ABSTRACT
Background and aims: Melissa officinalis is one of the most consumed plants in the world which has many different therapeutic effects such as: sedative, antioxidative and antispasmodic effects. Nowadays, it is mostly used for its calmness effect and for improvement of quality of sleep. In this study we tried to evaluate the eventual effect of hydro-alcoholic extract of Melissa officinalis on learning and spatial memory in mice using Morris watermaze task
Methods: In this experimental study, 32 Balb/c mice were randomly divided into one control and three experimental groups. Control group received normal saline and experimental groups received hydro-alcoholic extracts of Melissa officinalis [25, 50 and 100 mg/kg, i.p.] for 7 days, and then spatial learning was evaluated for 5 consecutive days. For evaluating short-term and long-term memory, probe-trial experiments were performed in the day 5, 7 and 9. Data were analyzed using ANOVA and Tukey tests
Results: No significant difference was found between control group and experimental groups in learning [P>0.05]. The first probe-trial experiment showed a positive effect of lower dose of Melissa officinalis [25 mg/kg] on short-term memory [P<0.05]; while control animals were succeeded in making short-term memory in the second probe trial experiment. Performing the third probe trial experiment in the day 9, we demonstrated that higher dose of Melissa officinalis [100 mg/kg] prevents from making short-term memory
Conclusion: Hydro-alcoholic extracts of Melissa officinalis have no significant effect on learning in watermaze task. Melissa officinalis increases short-term memory in lower dose; however, it may have prevention effect on making short-term memory in higher dose