Antidepressant-like activity of ellagic acid in unstressed and acute immobilization-induced stressed mice

Background: the aim of present study was to evaluate antidepressant-like activity of ellagic acid in swiss young male albino mice; and to explore the possible underlying mechanisms for this activity. methods: mice were immobilized for 150 min once only for induction of stress. ellagic acid (8.75,17.5,35 mg/kg,po) and fluoxetine (20 mg/kg,ip) per se were administered to unstressed and stressed mice; and immobility periods were recorded using tail suspension test and forced swim test. the plasma nitrite levels were also estimated in unstressed and stressed mice. effects of 7-nitroindazole (nnos inhibitor),aminoguanidine (inos inhibitor),prazosin (α1-adrenoceptor antagonist),sulpiride (selective d2-receptor antagonist),and p-chlorophenylalanine (p-cpa - tryptophan hydroxylase inhibitor) on antidepressant-like activity of ellagic acid were also evaluated. results: ellagic acid (17.5 and 35 mg/kg,po) and fluoxetine per se significantly decreased immobility periods of unstressed and stressed mice,indicating significant antidepressant-like activity. there was no significant effect on locomotor activity of the mice. ellagic acid significantly decreased the plasma nitrite levels in stressed mice only. aminoguanidine significantly potentiated antidepressant-like activity and plasma nitrite decreasing effect of ellagic acid (35 mg/kg) in stressed mice. 7-nitroindazole did not enhance antidepressant-like activity and plasma nitrite decreasing effect of ellagic acid in unstressed mice. prazosin and p-cpa significantly attenuated antidepressant-like effect of ellagic acid (35 mg/kg) in unstressed mice only. conclusion: thus,ellagic acid showed antidepressant-like activity in unstressedmice probably by interaction through adrenergic and serotonergic systems.on the other hand,antidepressant-like activity of ellagic acid in stressed mice might be through inhibition of inducible nos. copyright © 2012 by institute of pharmacology.