依托咪酯对神经元缺氧损伤的保护及其作用机制

目的观察依托咪酯对大鼠海马神经元缺氧损伤的保护作用及其机制。方法用原代培养的新生大鼠海马神经细胞建立缺氧模型,用MTT法测定神经元存活率。采用激光扫描共聚焦显微镜动态监测单个海马神经元Ca2+]i随缺氧或加入谷氨酸、KC l前后的实时变化。结果依托咪酯在1.2~4.8 mg.L-1范围内,可剂量依赖性地降低神经元缺氧损伤时的细胞死亡率(P<0.05)。0.3~4.8 mg.L-1依托咪酯能抑制缺氧及50 mmol.L-1KC l引起的Ca2+]i升高(P<0.05),仅在4.8 mg.L-1时才抑制1 mmo.lL-1谷氨酸所致的Ca2+]i升高(P<0.01)。结论依托咪酯对离体大鼠海马神经元缺氧性损伤具有保护作用,其机制可能与依托咪酯抑制缺氧引起Ca2+]i异常升高有关。

Protective effects and mechanisms of etomidate on anoxia injury in cultured rat hippocampal neurons

Aim To investigate the protective effects of etomidate on cultured rat hippocampal neurons subjected to anoxia injury and its mechanism.Methods Hippocampal neurons of neonatal rat,which had been cultured in vitro for 10 days,were allocated to control groups and etomidate-treating groups.The neurons were exposed to oxygen-glucose deprivation for 24 h.The cell survival rate in each group was evaluated using MTT colorimetry.To explore the effect of etomidate on neuronal calcium overload evoked by anoxia or 50 mmol·L~(-1) KCl or 1 mmol·L~(-1) glutamate,fluo-3,a fluorescent probe,was used for imaging of intracellular calcium in laser scanning confocal microscope(LSCM)to measure real-time changes of Ca~(2+)]_i in cultured rat hippocampal neurons.Results The hippocampal neurons developed acute neuronal swelling and widespread neuronal degeneration following anoxia for 24 h.Etomidate at concentrations of 1.2～4.8 mg·L~(-1) attenuated the neuronal injury in a dose-dependent manner(P<0.05).Etomidate at concentrations of 0.3～4.8 mg·L~(-1)inhibited Ca~(2+)]_i elevation caused by anoxia or KCl which induced the opening of the voltage-gated calcium ion channels(P<0.05).4.8 mg·L~(-1) etomidate inhibitedCa~(2+)]_i elevation caused by glutamate,an agonist of the N-methyl-D-aspartate(NMDA)receptor(P<0.01).Conclusion Etomidate can effectively protect cultured hippocampal neurons from anoxia injury.The mechanism may be partially due to inhibition of Ca~(2+)]_i overload via the voltage-gated calcium ion channels and the NMDA receptor calcium ion channels.