短暂缺血再灌注后大鼠海马神经营养因子3 mRNA表达的变化

目的　观察缺血和再灌注不同时间大鼠海马不同区域神经营养因子 3(NT 3)mRNA表达的变化及其与神经元凋亡的关系。方法　用Smith法制备前脑缺血和再灌注大鼠模型 ;随机引物法标记NT 3cDNA探针 ;原位杂交检测NT 3mRNA表达情况 ;原位末端标记法检测凋亡神经元。结果　前脑短暂缺血后 ,海马CA1、CA2、CA3区和齿状回NT 3mRNA表达均一过性下降 ,并随再灌注进一步加重 ,尤以CA1区下降幅度明显 ,且持续时间长 ,此后各区逐渐恢复正常水平 ;CA4区NT 3mRNA表达无显著性变化 ;各脑区、各时段NT 3mRNA表达水平与神经元凋亡呈显著负相关。结论　前脑缺血和再灌注后 ,NT 3表达的减少可能是神经元凋亡的重要原因之一

The variations of NT-3 mRNA expression in hippocampi of rats after transient forebrain ischemia and reperfusion

Objectives To investigate the changes of neurotrophin 3 (NT 3) mRNA expression in hippocampi of rats after transient forebrain ischemia and reperfusion and to find out their relationships with neuron apoptosis.Methods Animal models of forebrain ischemia and reperfusion were prepared following the method described by Smith. NT 3 mRNA was examined by in situ hybridization with cDNA probe labelled by random primers and apoptotic neurons were stained by means of in situ nick end labeling.Results A transient but significant decrease in NT 3 mRNA was observed in the regions of CA1,CA2,CA3 and dental gyrus and the decrease was aggravated during a certain period of further reperfusion.Then the level of the concerned mRNA returned to or towards baseline.The most prominent change in both severity and duration was observed in CA1.However,no significant change was found in CA4.Negative correlation was indicated by statistic analysis between the levels of NT 3 mRNA and the amount of apoptotic neurons in all regions of hippocampi.Conclusion The decrease in NT 3 expression in hippocampus may play an important role in neuron loss after forebrain ischemia and reperfusion.