Hu Bo, Sun Sheng-gang, Mei Yuan-wu
Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022.
Zhongguo Zhong Xi Yi Jie He Za Zhi. 2003 Jun;23(6):436-40.
To study the effect of Ginkgo biloba extract (GbE) on dynamic equilibrium of free radicals and amino-acids in cortex of rats with cerebral ischemia/reperfusion (I/R) injury and its influence and characteristics to intracellular free calcium concentration ([Ca2+]i) in primary cultured hippocampal neuron of rats.
Amino-acids were quantified by high performance liquid chromatographic (HPLC) analysis. Concentration of MDA and GSH-Px were determined by thiobarbituric acid (TBA) technique. SOD was assayed through xanthine method, and microfluoremetric technique was used to assay the change of [Ca2+]i and its characteristics.
Compared with the non-treated groups, at all time points (3 hrs after ischemia, 1 and 2 hrs after I/R separately), in the GbE treated groups, the levels of Glu, Asp and MDA were lower and SOD and GSH-Px were higher (P < 0.01 or P < 0.05), the GABA and Gly levels were lower in groups treated with middle (10 mg/kg) or high dosage (15 mg/kg) of GbE (P < 0.05). Compared with the group treated with small dosage GbE (5 mg/kg), Glu, Asp and MDA were lower and GABA, Gly, SOD and GSH-Px were higher in the groups treated with middle or high dosage of GbE (P < 0.05), while the difference in the latter two groups was insignificant. Level of [Ca2+]i in cultured neurons treated with 1 x 10(-5) mol/L glutamate combined 25 micrograms/ml GbE for 20s was lower with lower peak value and longer time for reaching the peak than that in neurons treated with 1 x 10(-5) mol/L glutamate alone. Besides, the time of decline phase was also shorter in the former, so the flatform stage was prolonged. The response was recovered by re-applying of glutamate after [Ca2+]i back to base line.
GbE can protect damaged neurons through keeping the balance of inhibitory/excitatory amino-acids, enhancing free radicals scavengers system, and inhibiting the effect of glutamate to [Ca2+]i.
研究银杏叶提取物（GbE）对脑缺血/再灌注（I/R）损伤大鼠皮质自由基和氨基酸动态平衡的影响及其对大鼠原代培养海马神经元细胞内游离钙浓度（[Ca2+]i）的影响和特点。
采用高效液相色谱（HPLC）分析法对氨基酸进行定量分析。采用硫代巴比妥酸（TBA）技术测定丙二醛（MDA）和谷胱甘肽过氧化物酶（GSH-Px）的浓度。通过黄嘌呤法测定超氧化物歧化酶（SOD），并采用显微荧光技术测定[Ca2+]i的变化及其特点。
与未处理组相比，在所有时间点（缺血后3小时、I/R后1小时和2小时），GbE处理组中谷氨酸（Glu）、天冬氨酸（Asp）和MDA水平较低，SOD和GSH-Px水平较高（P<0.01或P<0.05），中剂量（10mg/kg）或高剂量（15mg/kg）GbE处理组中的γ-氨基丁酸（GABA）和甘氨酸（Gly）水平较低（P<0.05）。与低剂量GbE（5mg/kg）处理组相比，中剂量或高剂量GbE处理组中的Glu、Asp和MDA水平较低，GABA、Gly、SOD和GSH-Px水平较高（P<0.05），而后两组之间的差异不显著。用1×10(-5)mol/L谷氨酸联合25μg/ml GbE处理20s的培养神经元中的[Ca2+]i水平低于单独用1×10(-5)mol/L谷氨酸处理的神经元，峰值较低，达到峰值的时间较长。此外，前者下降期的时间也较短，因此平台期延长。在[Ca2+]i恢复到基线后重新应用谷氨酸可使反应恢复。
GbE可通过维持抑制性/兴奋性氨基酸平衡、增强自由基清除系统以及抑制谷氨酸对[Ca2+]i的作用来保护受损神经元。
