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

Objective: We conducted, in a randomized, placebo-controlled manner, behavioral testing on mice offspring exposed antenatally to the herbal antidepressant Saint John’s wort (Hypericum). Study Design: 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. Results: 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. Conclusion: Antenatal exposure to a therapeutic dose of Saint John’s wort showed no long-term deficits on selected behavioral tasks by developing mice offspring. (Am J Obstet Gynecol 2000;183:1225-31.)