腺苷抑制P2X7和N-甲基-D-天冬氨酸受体诱导的视网膜神经节细胞死亡

Inhibiting effect of adenosine on retinal ganglion cells death induced by P2X7 and N-methyl-D-aspartate receptors

目的研究腺苷（adenosine）对嘌呤受体P2X7和谷氨酸N-甲基-D-天冬氨酸（NMDA）受体激活诱导的大鼠视网膜神经节细胞（RGC）死亡的神经保护作用。方法（1）对新生Long-Evan大鼠进行上丘注射荧光标记物荧光金（aminostilbamidine）以标记RGC，检测P2X7激动剂BzATP（50μmol/L）、谷氨酸NMDA受体激动剂（100μmol/L）和腺苷（300μmol/L）对体外培养RGC存活率的影响；（2）体外培养未经荧光金标记的新生大鼠RGC，以10μmol/L钙离子（Ca^2＋）荧光染料Fura-2乙酸甲酯（Fura-2Am）标记后，利用Ca^2＋影像测定仪分别测定BzATP、NMDA和腺苷对RGC内Ca^2＋浓度的影响。结果BzATP和NMDA均可引起体外培养的RGC死亡，BzATP在50μmol/L、NMDA在100μmol/L浓度下，均杀死约30%RGC。而300μmol/L腺苷则可明显减轻两者对RGC的毒性作用，使RGC存活率分别从68.9%±2.3%、69.9%±3.2%提高至91.2%±3.5%（P〈0.001）、102.1%±3.9%（P〈0.001）。BzATP可引起RGC内Ca^2＋持续升高，在50μmol／L浓度下可使细胞内Ca^2＋升高至（1183±109）nmol／L。在300μmol／L腺苷作用下，BzATP介导的Ca^2＋升高幅度显著降低，仅升高为（314±64）nmol／L（P〈0.001）。结论腺苷能阻止P2X，受体和NMDA受体激活诱导的RGC死亡和细胞内钙离子浓度升高，具有神经保护作用。

Objective To evaluate the inhibiting effect of adenosine on rat retinal ganglion cells （RGC） death induced by P2X7 and N-methyl-D-aspartate （NMDA） receptor. Methods （1） Long-Evan neonatal rats were back labeled with aminostilbamidine to identify RGC. The viability of RGC affected by P2X7 excitomotor BzATP （50 μmol/L）, glutamate receptor exeitomotor NMDA （100 μmol/L） and adenosine （300 μmol/L） was detected. （2） RGC from the retinae of unlabeled neonatal rats were cultured in vitro. After labeled with Fura-2 methyl acetate, an intracellular calcium indicator, the effect of BzATP, NMDA and adenosine on intracellular Ca2＋ level was detected by Ca^2＋ imaging system. Results Both BzATP （50 μmol/L） and NMDA （100 μmol/L） could kill about 30% of the RGC. Cell death was prevented by adenosine （300 μmol/L） with the cell viability increased from （68.9±2.3）% and （69.9±3.2）% to （91.2±3.5）% （P〈0.001） and （102.1±3.9）% （P〈0.001）, respectively. BzATP （50 μmol/L） led to a large, sustained increase of intraeellular Ca^2＋ concentration to （1183±109） nmol/L. After the adenosine intervened, Ca^2＋ concentration increased slightly to （314±64） nmol/L （P〈0. 001）. Conclusion Adenosine may prevent RGC death and increase of intracellular Ca^2＋ concentration from P2X7-and NMDA receptor stimulation.