Effects of bilobalide on hypoxia/hypoglycemia-stimulated glutamate efflux from rat cortical brain slices

The aim of this study was to investigate the effects of bilobalide, the postulated active constituent of Ginkgo biloba, on the release of glutamate elicited by hypoxia/hypoglycemia. Cortical slices were prepared from rat brain and perfused with normal artificial cerebrospinal fluid (aCSF) or aCSF made hypoxic by gassing with nitrogen, and hypoglycemic by removal of glucose. The perfusate was assayed for glutamate by HPLC. After 30 minutes, perfusion with hypoxic/hypoglycemic aCSF glutamate levels in the perfusate were increased approximately 5-fold. Bilobalide at 1, 10, and 100 microM, when perfused together with hypoxic/hypoglycemic aCSF, significantly reduced the release of glutamate. This study suggests that the reported neuroprotective properties of bilobalide may, in part, be mediated through its ability to reduce glutamate efflux, thus leading to a decrease in the excitotoxic effects of this neurotransmitter.