Effects of an extract of Ginkgo biloba on noradrenergic systems of rat cerebral cortex.

Oral treatment of rats with Ginkgo biloba extract (Gb) elicited a biphasic effect on normetanephrine (NMN) content of cerebral cortex; an initial decrease was evident after 45 minutes, followed by a marked increase that was evident after 14 days. Chronic treatment with Gb led to decreases in the density of 3H-dihydroalprenolol binding (after 27 days or 2 months) and in isoproterenol-stimulated adenylate cyclase activity (after 2 months) of the cerebral cortex. Taken together, these results indicate that the effects of Gb on the central beta-adrenergic system might be involved in its therapeutic actions.