脑梗塞后脑代谢及高糖对脑代谢影响的研究

Studies of cerebral metabolism and effect of hyperglycemia on the metabolism after ischemia in rat in vivo

目的 探测脑梗塞后梗塞区及对照区域的代谢变化并探讨高糖对梗塞区域代谢的影响 ,为脑梗塞的临床治疗提供理论依据。方法 雄性SD大鼠左侧颈内动脉插线法制作脑梗塞模型。用磁共振定域1H MRS技术 ,在同一活体上分别连续检测梗塞区及对照区域代谢变化。结果 脑梗塞后梗塞区NAA、Cho、Pcr/Cr强度均低于对照区 ,并出现明显的Lac信号。NAA在脑梗塞急性期明显降低。加用高糖 1～ 2h内 ,所选区域NAA、Cho、Pcr/Cr均有小幅回升 ,随后又渐趋下降 ;原有乳酸信号成倍增加 ( 2 4倍 )。结论 ( 1)NAA的变化可反映神经元的功能状况 ,可望作为MRS早期诊断脑梗死的有效指标。 ( 2 )Lac峰的出现是脑梗死早期的敏感指标 ,其含量变化可直接反映局部病理代谢状况。 ( 3)NAA和Cho的降低证明脑梗塞后即发生细胞膜结构、膜功能及膜间连接损伤 ;( 4)高糖可加剧脑梗塞区的病理代谢导致Lac大量积聚 ;( 5 )采用MRS定域波谱技术可更精确、更客观地连续检测活体动物大脑各区域代谢变化。

Objective To detect metabolite changes in the ischemic cores and contralateral areas directly and continuously, and to study the effect of hyperglycemia on the metabolism of the both areas after ischemia in rat brain. Methods We used left MCA ischemic suture model in SD rat to continuously detect and record the metabolites of the VOIs in the same body in vivo by the localized 1H-MRS technique. Results There are significant differences in NAA, Cho, Pcr/Cr between ischemic areas and contralateral areas. These metabolites declined continuously after ischemia in the ischemic areas, but kept normal in contralateral areas. In the early-period of post-ischemia NAA was dropped sharply. Lac was detected only in the ischemic areas. After administering high-glucose, NAA, Cho, Pcr/Cr increased and followed a decline during 1～2 hrs. Lac signals were increased greatly (2.4 fold). Conclusions (1)NAA greatly decreased in ischemic cores after ischemia. The change of NAA could reflect the function of neurons and could be one of the important evidences for MRS to diagnose earlier ischemia. (2) Lac is another important evidence and its changes directly reflect the condition of pathologic metabolism in ischemic areas. (3)There are damages in the structure and function of cellular membranes and the connections between membranes. (4) Administering high-glucose depraved pathologic metabolism and resulted in Lac accumulation in ischemic areas. (5) The localized 1H-MRS technique can continually detect the metabolites in specific areas more exactly and objectively in the same body in vivo.