Neuroprotective effects of Ginkgo biloba extract in brain ischemia are mediated by inhibition of nitric oxide synthesis

We studied the effects of pre-treatment (15 days) with oral administration of Ginkgo biloba extract (Ph-Gb 37,5-150 mg/kg) on brain malonildialdehyde (MDA), brain edema, brain nitrite and nitrate and delayed neuronal death fo llowing transient cerebral ischemia in the Mongolian gerbil. Survival was n ot modified, however, pre-treatment with Ginkgo biloba significantly and in a dose-dependent way reduced post-ischemic brain MDA levels and post-ische mic brain edema. Delayed neuronal death in the CA(1) of the hippocampus was attenuated by the highest dose of the extract. Increase of nitrite and nit rate was observed after cerebral ischemia in the hippocampus and it was dos e-dependently reduced in animals pretreated with Ph-Gb, thus suggesting tha t neuroprotective effects of Ginkgo biloba may be due to an inhibitory acti on on nitric oxide formation. (C) 2000 Elsevier Science Inc. All rights res erved.