Résumé
The aim of this study was to evaluate the antidepressant like actions of butanol fraction from methanol extract of Opuntia dillenii in rodents. Butanol fraction of Opuntia dillenii was obtained by bioassay guided fractionation of crude methanol extract of the plant. This fraction was evaluated for antidepressant activities using two behavioral tests viz a] forced swimming and b] tail suspension tests in rats and mice, respectively. Additionally, locomotor test and yohimbine potentiation test were also conducted to understand its mechanism of antidepressant action. One way analysis of variance and Student's paired t test were applied for data analysis and significance was defined as P value <0.05. The butanol fraction significantly reduced the duration of immobility time of rodents in a dose dependant manner in both behavioral stress models, indicating antidepressant-like activity. This effect was comparable to that of reference antidepressant drug fluoxetine. The butanol fraction did not cause significant change in the locomotor activity suggesting that the butanol fraction is not a stimulant. The four times higher mortality in yohimbine treated mice in the presence of butanol fraction as compared to control animals implies that butanol fraction is probably interfering with the alpha -2 feedback mechanism of norepinephrine. Hence the butanol fraction of Opuntia dillenii possesses antidepressant activity therefore it merits further research to identify active moiety and to further elaborate the possible mechanism[s] involved in its antidepressant activity