Chronic administration of St. John's Wort attenuates alcohol intake and brain indoleamine 2, 3-dioxygenase activity in mice.

Present study aims to elucidate the effects of chronic administration of St. John's Wort (SJW) (500mg/kg) on brain tryptophan (TRP) metabolites and indoleamine 2-3 dioxygenase (IDO) activity in alcohol treated mice. Locally bred Albino BALB/c mice, weighing 20-25g were divided into three groups (untreated controls, Alcohol, Alcohol +Drug) having 6 mice in each. Freshly prepared ethanol solution was administered in drinking water in the proportion of 5% for three days or 8% for 3 weeks to two groups. After 3 weeks drug group was treated with SJW (dissolved in ethanol: saline 1:3 v/v) at a dose of 500mg/kg was administered orally for 1 week. During treatment alcohol intake was monitored .In present finding chronic administration of SJW significantly reduced ethanol intake by 78.6% (P<0.001) in mice. Data analyzed by student's t-test indicates that SJW remarkably reduce kynurenine (KYN) by 60.9% (P<0.001) and KYN/TRP ratio (IDO) activity) by 70.9% (P<0.001) in brain. Low serotonin level promotes alcohol intake. Presentresults suggest that SJW decreases alcohol intake by inhibiting IDO thereby shifting TRP catabolism towards serotonin synthesis.