Motor function in young and aged hemiplegic rats: effects of a Ginkgo biloba extract.

We have previously shown beneficial effects of a Ginkgo biloba extract (EGb761-IPSEN) in accelerating functional recovery from hemiplegia induced by unilateral motor cortex ablation. Here, we report the behavioral and histological effects of various dose regimes of EGb761. In young rats (3 months), 10 mg/kg/day for 7 days produced an improvement in motor performance, relative to untreated controls, on the last day of treatment. Applying a priming (P)-maintenance (M) dose regime (P-7 = 7 days, M-21 = 21 days), a P-7 of 50 (all doses expressed in mg/kg/day) and a M-21 of 10 promoted recovery from the second day after surgery. However, in aged rats (26-28 months old) this treatment ameliorated motor performance only after the 10th day of treatment. A P-7 of 100 or 200 and a M-21 of 50 or 100 produced an acceleration of behavioral recovery in aged animals. Improvement was evident by the fifth day of treatment and was maintained after the treatment regimen. These two groups also demonstrated reduced glial fibrillary acid protein (GFAP) immunostaining and ex vacuo hydrocephalus. Thus, the confirmed efficacy of EGb in hemiplegic rats can be enhanced by an appropriate posology.