Antidepressant-like effect of ethanol extract from Paeonia lactiflora in mice.

The present study investigated the antidepressant effect of ethanol extract of Paeonia lactiflora (EPL) in mice using forced swim test, tail suspension test, open-field test and reserpine test. Our results showed that intragastric administration of EPL at the doses of 250 and 500 mg/kg for seven days significantly reduced the duration of immobility in both forced swim test and tail suspension test. EPL at the dose of 500 mg/kg was as effective as the positive control (chlorimipramine, 20 mg/kg) in these tests. However, these treatments did not affect the number of crossing and rearing in the open-field test. Treating mice with EPL at the doses of 250 and 500 mg/kg significantly antagonized reserpine-induced ptosis and hypothermia. However, at the dose of 125 mg/kg, EPL antagonized only the hypothermia but not ptosis induced by reserpine. The results clearly demonstrated the antidepressant effect of Paeonia lactiflora in animal models of depression. The action of Paeonia lactiflora may be mediated via the central monoaminergic neurotransmitter system.