Effects of gingko biloba extract on glutamate-induced [Ca2+]i changes in cultured cortical astrocytes after hypoxia/reoxygenation, H2O2 or L-glutamate injury
Li, Z.; Lin, X-ming.; Gong, P-li.; Du, G-hua.; Zeng, F-dian.
Yao Xue Xue Bao 40(3): 213-219
2005
ISSN/ISBN: 0513-4870 PMID: 15952591 Document Number: 593747
Aim: To investigate glutamate-induced [Ca2+]i changes in cultured rat neonatal cortical astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury. In the meantime, the effects of G. biloba extract (GbE) were examined. Methods: [Ca2+]i changes in astrocytes were monitored by laser scanning confocal microscopy with the Ca2+ sensitive fluorescent probe fluo-3. Results: After astrocytes were impaired by hypoxia/reoxygenation, H2O2 (50 micro mol l-1) or L-glutamate (0.25 mmol l-1), the exogenous glutamate (27 micro mol l-1) could not induce increase of [Ca2+]i, but decrease by (3.3+or-1.6)%, (81+or-11)% and (81+or-7)%, respectively. Pretreatment with GbE (10 mg l-1) could not improve injured astrocytic glutamate response. But after pretreatment with GbE (100 mg l-1), glutamate-induced [Ca2+]i elevation of astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury were (135+or-98)%, (117+or-93)% and (89+or-36)%, respectively. Nimodipine (1.6 mg l-1) could also reverse the abnormal response of astrocytes after different injury. Conclusion: Hypoxia/reoxygenation, H2O2 and high concentration of L-glutamate impaired astrocytes' response to exogenous L-glutamate, and then bidirectional communication between astrocytes and neurons could not take place. GbE could improve the abnormal responses and maintain the normal function of astroglical network. These effects support that GbE has potential beneficial actions against brain injury.