Effect of antenatal exposure to Saint John's wort (Hypericum) on neurobehavior of developing mice.

Abstract

We conducted, in a randomized, placebo-controlled manner, behavioral testing on mice offspring exposed antenatally to the herbal antidepressant Saint John's wort (Hypericum ). A daily dose of Saint John's wort (0.75 mg/g of food consumed), equivalent to that in human beings according to body surface, was chosen because it has been shown to cause an antidepressant effect in adult mice. CD-1 mice were randomly assigned to consume either Saint John's wort (n = 45) or a placebo (n = 45) for 2 weeks before conception and throughout gestation. Behavioral testing consisted of early developmental tasks of geotaxis, separation vocalization, and homing, followed by motor, anxiety, and depression assessments into adulthood. Birth weights of male offspring were less in the Saint John's wort group than in the placebo group (1.68 vs. 1.75 g; P<.01). Offspring in both treatment groups showed no long-term statistical differences in early developmental tasks, locomotor activity, and exploratory behavior throughout development. Performances on a depression task (forced swim) and on anxiety tasks (elevated plus maze as juveniles and adults) revealed no differences between treatment groups. Antenatal exposure to a therapeutic dose of Saint John's wort showed no long-term deficits on selected behavioral tasks by developing mice offspring.