低氧与缺血诱导培养海马和皮质神经元钙应答反应的比较

COMPARISON OF THE INTRACELLULAR CALCIUM CHANGES INDUCED BY HYPOXIA"ISCHEMIA IN CULTURAL CEREBRAL CORTICAL AND HIPPOCAMPAL NEURONS

目的 :钙作为重要信使参与多种生理和病理代谢过程 ,而且在缺血性神经元损伤机制中起着重要的作用。本实验模拟脑缺血的病理生化改变 ,用激光扫描共聚焦显微镜 (LSCM)和Fluo 3荧光探针标记技术 ,观察低氧缺血状态下体外培养的海马、皮质神经元内钙浓度的变化。方法 :用 1 0 0 μmol/L氰化钠造成细胞低氧 ;1 0 0 μmol/L氰化钠和 3.5mmol/L碘醋酸盐模拟在体完全性脑缺血 ;1mmol/LL 谷氨酸模拟在体脑缺血时兴奋性氨基酸大量释放 ;无葡萄糖介质剥夺细胞能量代谢的底物。结果 :低氧使海马神经元 [Ca2 + ]i显著升高 ,但有两种不同的钙振荡现象。谷氨酸引起海马神经元 [Ca2 + ]i持续升高 ,但峰值低于低氧组。缺血组未见 [Ca2 + ]i大幅升高。葡萄糖缺如不引起 [Ca2 + ]i升高。结论 :低氧和谷氨酸引起的神经元损害是能量依赖性的。轻度酸中毒可阻止胞内Ca2 + 升高。糖对神经元具有保护作用 ,但单纯无糖引起的神经元损害与Ca2 + 超载机制无关。

Objective:To study the changes in intracellular free calciumion concentration ([Ca 2+ ]i) in response to hypoxia/ischemia in cultured cerebral cortical and hippocampal neurons.Methods:The cultures were exposed to hypoxia/ischemia medium by adding L glutamic acid,NaCN,iodoacete acid and glucose free medium.[Ca 2+ ]i of cortical and hippocampal neurons was measured by laser scanning confocal microscope (LSCM) at room temperature.Results:Application of NaCN produced 2 different patterns of [Ca 2+ ]i elevation in hippocampal neurons.A rapid large [Ca 2+ ]i elevation in some neurons and a gradual increase in [Ca 2+ ]i with the peak value of [Ca 2+ ]i lower than the former.Glutamate made a sustained [Ca 2+ ]i elevation,but peak calcium levels were lower than in cyanide hypoxia.In contrast with groups described above,elevation of calcium levels did not occur in the deprivation of glucose at all.Conclusion:The neuronal lesions induced by hyposia,exitotoxicity of L lutamate are energy dependent.Mild acidosis can prevent a influx of calcium.Glucose may prevent neurons from lesions,but glucose free medium can not increase [Ca 2+ ]