Effects of gingko biloba extract on glutamate-induced [Ca2+]i changes in cultured cortical astrocytes after hypoxia/reoxygenation, H2O2 or L-glutamate injury.

Aim To investigate glutamate-induced [Ca 2+] i changes in cultured rat neonatal cortical astrocytes after hypoxia/reoxygenation, H 2O 2 or high concentration of L-glu tamate injury. In the meantime, the effects of Gingko biloba extract (Gb E) were examined. Methods [Ca 2+] i changes in astrocytes were monito red by laser scanning confocal microscopy with the Ca 2+ sensitive fluoresc ent probe fluo-3. Results After astrocytes were impaired by hypoxia/reoxygenation , H 2O 2 (50 μmol·L -1) or L-glutamate (0.25 mm ol·L -1), the exogenous glutamate (27 μmol·L -1) could not in duce increase of [Ca 2+] i, but decrease by (3.3±1.6)%, (81±11)% and (81±7)%, respectively. Pretreatment with GbE (10 mg·L -1) co uld not improve injured astrocytic glutamate response. But after pretreatment wi th GbE (100 mg·L -1), glutamate-induced [Ca 2+] i ele vation of astrocytes after hypoxia/reoxygenation, H 2O 2 or high c oncentration of L-glutamate injury were (135±98)%, (117±93)% and (89±36) %, respectively. Nimodipine (1.6 mg·L -1) could also reverse the abno rmal response of astrocytes after different injury. Conclusion Hypoxia/reoxygenation, H 2O 2 and high concentration of L-glutamate impaired astrocytes′ response to exogenous L-glutamate, and then bidirectional communication between astrocytes and ne urons could not take place. GbE could improve the abnormal responses and mai ntain the normal function of astroglical network. These effects support that G bE has potential beneficial actions against brain injury.