EGb761 protects hydrogen peroxide-induced death of spinal cord neurons through inhibition of intracellular ROS production and modulation of apoptotic regulating genes.

The present study was conducted to investigate whether Ginkgo biloba extract (EGb) 761 could protect spinal cord neurons from H(2)O(2)-induced toxicity. In primary spinal cord neurons isolated from embryonic day 14 rats, H(2)O(2) administration resulted in a significant decrease in the survival of spinal cord neurons. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and Hoechst 33342 nuclear staining showed that these cells die by apoptosis. Such neuronal death, however, was significantly reversed by EGb761 in a dose-dependent manner. Moreover, a marked increase in intracellular free radical generation was found after the H(2)O(2) administration which could be reversed almost completely by EGb761, indicating that inhibition of free radical generation is an important mechanism of the anti-apoptosis action of EGb761. Finally, treatment of cells with H(2)O(2) for 12 h reduced the expression of Bcl-2, an anti-apoptotic gene, by 70% but showed no effect on the level of Bax, a pro-apoptotic gene. EGb76 treatment, however, significantly reversed H(2)O(2)-induced reduction of Bcl-2 expression and inhibited Bax expression by 2.3-fold. Thus, our study provided evidence showing that the protective effect of EGb761 on spinal cord neuronal apoptosis after oxidative stress is mediated, at least in part, by its anti-oxidative action and regulation of apoptosis-related genes Bcl-2 and Bax.