Evaluation of the anxiolytic effects of chrysin, a Passiflora incarnata extract, in the laboratory rat.

The definitive anxiolytic effects of Passiflora incarnata are unknown. We studied the potential anxiolytic effects of chrysin, a Passiflora extract, and the purported modulation of the benzodiazepine receptor on the GABA(A) receptor in laboratory rats. We hypothesized that chrysin decreases anxiety via interaction with the GABA(A) receptor in laboratory rats as measured by elevated plus-maze (EPM), corticosterone, and catecholamine assays. We randomized 44 male Sprague-Dawley rats in a double-blind, placebo-controlled, between-subjects experimental design. Each animal received an intraperitoneal injection of (1) vehicle (DMSO 4%), (2) chrysin, 2 mg/kg, (3) midazolam, 1.5 mg/kg, or (4) flumazenil, 3 mg/kg and chrysin, 2 mg/kg. The EPM was used to evaluate the behavioral component of anxiolysis, and catecholamine and corticosterone assays were examined to measure the neurohormonal effects of anxiety. No statistical difference was found among groups in catecholamine and corticosterone levels. Midazolam significantly decreased anxiety compared with control and flumazenil plus chrysin groups (P <.05); there was no significant difference compared with the chrysin group. These data suggest that chrysin may have anxiolytic properties similar to midazolam but to a lesser magnitude at the 2 mg/kg dose used in this study.