Evaluation of Acute Anxiolytic and Antidepressant Activity of Ethanolic Extract of Ocimum sanctum (Tulsi) Leaf in Wistar Albino Rats

Anxiety and depression are common psychiatric disorders, often requiring prolonged pharmacotherapy with many adverse effects. So, traditionally used medicinal plants may be safer alternatives. Reports of anxiolytic and antidepressant activity of Ocimum sanctum are scarce and no studies are available on the combination of plant extract with reduced dosage of standard drugs. Our aim was to evaluate the anxiolytic and antidepressant activities of ethanolic extract of leaves of Ocimum sanctum. Twenty four Wistar albino rats of either sex were divided randomly into four groups (n=6) and were administered normal saline 1ml/kg, Ocimum sanctum ethanolic extract (OSEE) 100mg/kg, Alprazolam 5mg/kg or Fluoxetine 10mg/kg and combination of OSEE and half dose Alprazolam/Fluoxetine respectively. Elevated plus maze test (EPM) and light and dark arena (LDA) models of anxiety were carried out. Washout period (15 days) was followed by administration of plant extract and standard drug. Forced swim test and Modified Tail Suspension Test models of depression were done for evaluation of antidepressant activity. Results were expressed as Mean ± SEM. Statistical significance was calculated using One way ANOVA followed by Tukey’s post hoc test, taking p<0.05 as significant at 95% C.I. OSEE and combination of OSEE and half dose of alprazolam demonstrated a significant anxiolytic effect (p<0.05, p<0.001) by increasing time spent in open arms/ light area and number of entries in open arms/ light area in the EPM and LDA models respectively when compared to normal control. The combination showed anxiolytic effect which was comparable to that of Alprazolam. However, none of the groups showed a significant antidepressant effect (p>0.05). Conclusions: Hence, OSEE and combination of half dose of alprazolam and OSEE demonstrated a significant anxiolytic activity but did not demonstrate a significant antidepressant activity on acute administration.