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

Yao Xue Xue Bao. 2005 Mar;40(3):213-9.

Abstract

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 Gingko 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 micromol x L(-1)) or L-glutamate (0.25 mmol x L(-)), the exogenous glutamate (27 micromol x L(-1)) could not induce increase of [Ca2+]i, but decrease by (3.3 +/- 1.6)%, (81 +/- 11)% and (81 +/- 7)%, respectively. Pretreatment with GbE (10 mg x L(-1)) could not improve injured astrocytic glutamate response. But after pretreatment with GbE (100 mg x L(-1)), glutamate-induced [Ca2+]i elevation of astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury were (135 +/- 98)%, (117 +/- 93)% and (89 +/- 36)%, respectively. Nimodipine (1.6 mg x 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.

MeSH terms

  • Animals
  • Astrocytes / cytology
  • Astrocytes / metabolism*
  • Calcium / metabolism*
  • Cell Hypoxia
  • Cells, Cultured
  • Cerebral Cortex / cytology
  • Cerebral Cortex / metabolism
  • Drugs, Chinese Herbal / isolation & purification
  • Drugs, Chinese Herbal / pharmacology*
  • Ginkgo biloba* / chemistry
  • Glutamic Acid / toxicity
  • Hydrogen Peroxide / toxicity
  • Plant Leaves / chemistry
  • Plants, Medicinal / chemistry
  • Rats
  • Reperfusion Injury

Substances

  • Drugs, Chinese Herbal
  • Glutamic Acid
  • Hydrogen Peroxide
  • Calcium