褪黑素在叠氮钠所致的海马锥体细胞钙超载中的神经保护作用

目的 观察叠氮钠对急性分离的大鼠海马锥体神经元胞内游离钙的作用以及不同浓度的褪黑素（Melwatonin, MT)的影响。方法 海马锥体细胞的急性分离，新型游离钙荧光探针Fluo-4AM负载海马锥体细胞，激光共聚焦动态检测胞内游离钙的变化及叠氮钠，褪黑和荷包牡丹碱的作用。结果 在孵育液中加入叠氮钠（0.8mg/ml）能使急性分离的海马锥体细胞胞内游离钙在200s内急剧升高并维持在高水平，处于钙超载状态。褪黑素能使NaN3所致的海马锥体细胞内处于超载状态的游离钙显著下降，并有量效关系。结论 叠氮钠导致海马神经细胞损伤的早期原因可能是钙超载，MT促进钙离子向细胞外的转运而抑制叠氮钠所致的钙超载。

Neuroprotective effect of melatonin on calcium overload of pyramidal cell in the hippocampus due to sodium azide

Objective To observe the effect of sodium azide on the intracellular free Ca 2+ concentration ([Ca 2+ ]i) in acute isolated pyramidale cells and the influence of melatonin at different dosages Methods The pyramidale cells in the CA1 of the hippocampus were isolated and loaded with the new fluorescence probe of free calcium Fluo 4 AM The dynamic real time changes of [Ca 2+ ]i in the pyramidale cells were analysed with laser scanning confocal microscope (LSCM) The influence of sodium azide, melatonin and Biculline on the [Ca 2+ ]i in pyramidale cells was also observed Results The [Ca 2+ ]i in the acute isolated pyramidale cells increased significantly and remained at high level of calcium overload 200 s after sodium azide (0 8 mg/ml) was added into the medium [Ca 2+ ]i decreased significantly when the cells were treated with melatonin at different dosages The effect of melatonin was in a dose dependent manner Conclusion The early cause resulting in neuron injury in the hippocampus due to sodium azide is probably calcium overload Melatonin can block the calcium overload by increasing the outflow of intracellular free Ca 2+