Protective effect of Ginkgo biloba extract (EGB 761) on free radical-induced changes in the electroretinogram of isolated rat retina.

The retina is a tissue particularly rich in polyunsaturated fatty acids and thus highly sensitive to lipid peroxidation initiated by oxygenated free radicals. By recording the electroretinogram (ERG) b wave amplitude on isolated rat retina, the authors have investigated the anti-oxidant properties of Ginkgo biloba extract (EGB 761). Two groups of rats were used: one group was treated with EGB 761 at a dose of 100 mg/kg/day per os for 10 days; the other one of untreated animals served as a control. At the end of the treatment (10 days), rats were sacrificed, one retina isolated and perfused in order to record ERG. Lipid peroxidation was induced by adding a mixture of (FeSO4 + Na ascorbate) to the perfusion solution. In the untreated rats a 50% decrease in ERG was observed after only 55 min. Such a delay in the decrease and subsequent maintenance of ERG b wave amplitude confirm that the anti-oxidant properties of EGB 761 can protect the retina against lipoperoxidation.