Effect of Ginkgo biloba extract EGb 761 on the nonspecific and humoral immune responses in a hypothalamic-pituitary-adrenal axis activation model.

We evaluated the immune response of healthy control and stressed Wistar rats submitted to hypothalamic-pituitary-adrenal (HPA) axis activation. Rats were treated with Ginkgo biloba extract (EGb 761) orally (100 mg/kg per day for 7 days). EGb 761 stimulated the digestion index of peritoneal and alveolar macrophages (PM and AM) of stressed rats. Likewise, the cellular immune response measured using the delayed-type hypersensitivity response to sheep red blood cells (SRBC) and the humoral immune response (measured through an anti-SRBC response), were also restored in stressed rats. Thus, this G. biloba extract possesses immunostimulatory activity in addition to its broad spectrum of pharmacological effects.