摘要目的研究银杏叶提取物(GBE)对大鼠缺血再灌注损伤皮质内自由基、氨基酸动态平衡的影响及其对原代培养的大鼠海马神经元内游离钙离子浓度([Ca2+]i)的影响和特征.方法采用的动物模型参照Zivin JV 的大脑中动脉线栓模型以获得缺血/再灌注损伤的皮质组织样本.采用高压液相色谱仪测量氨基酸的浓度;MDA和GSH-PX采用TBA法测量,SOD采用嘌呤法测量.使用显微荧光检测系统检测单个原代培养的海马神经元内游离钙离子浓度([Ca2+]i)的变化和特征.结果和对照组比较,治疗组中,SOD和GSH-PX 的浓度较高, MDA的浓度则明显降低, 谷氨酸、天门冬氨酸的浓度明显降低,而GABA的浓度在各个时间点均升高(P<0.01), Gly的浓度在一些时间点有所降低 (P<0.05), 5 mg/kg 组与10 mg/kg、15 mg/kg组间有显著差别,而后二者间差别无显著意义.当向原代培养的神经元同时给予1×10-5 mol/L谷氨酸和25 μg/mlGBE20秒时所诱导的[Ca2+]i明显低于单独使用1×10-5 mol/L谷氨酸所引起的[Ca2+]I的变化,其峰值明显下降,且Phase 1上升速度减慢,Phase 2的时间也有所缩短,二相之间的平台期相对延长,当其返回基线后,再次给予1×10-5 mol/L谷氨酸时,其反应可恢复.结论银杏叶提取物在大鼠脑再灌注损伤中可通过保持抑制性氨基酸/兴奋性氨基酸、自由基系统的平衡及快速抑制谷氨酸诱导大鼠海马神经元内游离钙浓度升高来保护受损的神经元的.

abstractsObjective To study the effect of Ginkgo biloba extract on rats during ischemia/reperfusion and its influence on intracellular calcium in hippocampal neurons. Methods Model of intraluminal occlusion of the middle cerebral artery (MCAO) was used to prepare the ischemia/reperfusion cortex tissue. Concentration of MDA was determined by measuring thiobarbituric acid-reactive substance. GSH-PX was quantified using the thiobarbituric acid (TBA) technique. SOD was assayed througha xanthine method. Endogenous amino acids were quantified by high performance liquid chromatographic (HPLC) analysis. Primary culturs of hippocampal neurons were prepared for a free intracellular calcium ([Ca2+]I ) assay by Fura-2 based single cell microfluoremetric technique.Results Comparing control and treatment groups, the concentration of SOD and GSH-PX were higher, whereas that of MDA was much lower; the concentration of glutamate and aspartate decreased and that of GABA increased markedly at all time point (P<0.01), Gly also decreased at some time points (P<0.05). The differences were significant between the groups of 10 mg/kg, 15 mg/kg and the groups of 5 mg/kg. When 1×10-5 mol/L glutamate was applied with 25 μg/ml ginkgo biloba extract to cultured neurons, the increase in [Ca2+]I was lower than that caused by applying glutamate alone. Its peak value was much lower and increased phase was longer, its declining phase was shorter. After returning to baseline, the application of 1×10-5 mol/L glutamate could induce the reaction to recover.Conclusions Ginkgo biloba extract could protect damaged neurons by keeping the balance of inhibitory/excitatory aminoacids, enhancing the free radical scavengers system, and inhibiting the effect of glutamate on [Ca2+]I.