咖啡因对谷氨酸诱导神经元凋亡的保护作用

目的　研究咖啡因对谷氨酸诱导的神经元凋亡是否具有保护作用，并对其机制进行探讨。方法　采用ＤＮＡ凝胶电泳分析及Ｈｏｅｃｈｓｔ３３２５８核染色方法进行凋亡分析；使用荧光指示试剂Ｆｕｒａ ２检测单细胞内游离钙浓度变化。结果　谷氨酸可诱导小脑颗粒神经元凋亡，咖啡因能拮抗谷氨酸的这一效应，其ＩＣ５０为５－０ｍｍｏｌ·Ｌ－１。咖啡因的这一保护作用不能被ｆｏｒｓｋｏｌｉｎ模拟，也不能被Ｒｐ ｃＡＭＰ阻断。此外，内质网Ｒｙａｎｏｄｉｎｅ受体阻断剂ｄａｎｔｒｏｌｅｎｅ也不能取消咖啡因的保护作用，咖啡因不影响谷氨酸诱导的钙超载。结论　咖啡因对谷氨酸诱导的神经元凋亡具有保护作用，这一保护作用与咖啡因升高细胞内ｃＡＭＰ和Ｃａ２＋水平的药理作用无关。

Protection of caffeine against neuronal apoptosis induced by glutamate

AIM To investigate the effect of caffeine on the neuronal apoptosis induced by glutamate. METHODS Agarose gel electrophoresis was used to analyse DNA fragmentation induced by glutamat. The survival rate of neurons was measured with Hoechst 33 258 nucleus staining analysis. Measurement of intracellular calcium was performed by means of microspectrofluorimetry and the Ca 2+ sensitive indicator Fura 2. RESULTS ① Caffeine could reduce the excitotoxicity of glutamate and prevent the neurons from apoptosis. The IC 50 =5 0 mmol·L -1 . ② The protective effects of caffeine were not mimicked by forskolin, and blocked by Rp cAMP and Dantrolene. CONCLUSION Caffeine can protect neurons from apoptosis induced by glutamate, but the protection is irrelevant to its pharmacological action of raising intracellular cAMP and Ca 2+ levels.