大鼠蛛网膜下腔出血后脑皮质中兴奋性氨基酸水平变化的微透析研究

The Change of Excitatory amino acids in the Cortex of Rats with Subarachnoid Hemorrhage Measured by Intracerebral Micro dialysis

目的观察蛛网膜下腔出血(Subarachnoid hemorrhage,SAH)后大鼠脑皮质细胞外液中兴奋性氨基酸(Excitatory Amino Acids,EAA)[主要包括谷氨酸(Glu)和天冬氨酸(Asp)]水平的变化规律,探讨SAH后脑损害的机制。方法将SD大鼠20只随机分为SAH组和对照组,每组各10只,将微透析探针置入大鼠右侧顶叶皮质,在不同的时间段进行定点采样,样本采用高效液相分析方法进行检测。结果SAH后0hGlu和Asp水平均明显高于对照组(P<0.001,P<0.01),而后Glu虽有波动但均高于基础水平;在SAH后1hAsp水平降至基础水平,25hAsp水平再次显著升高(P<0.01),而后呈升高趋势。结论SAH后大鼠脑皮质细胞外液中Glu和Asp在不同的时限有不同程度的升高,提示两者在SAH后的缺血性脑损伤中均起一定作用,但早期的神经细胞损伤主要与Glu有关,而Asp主要在中后期发挥作用。

Objective To observe the change law of excitatory amino acids （especially Glu and Asp） in the cortex of rats with subarachnoid hemorrhage, and try to find out the cerebral impaired mechanism after SAH. Methods Twenty SD rats were randomly divided into two groups, SAH group （n = 10） and control group （n = 10）. The micro dialysis probe was inserted into the right front parietal cortex, and micro dialysis samples were collected continuously at different time. The concentrations of Glu and Asp were analyzed with using high performance liquid chromatography （HPLC）. Results 0 h after SAH the concentrations of Glu and Asp in the extracellular fluid were higher than those of the control （Glu：P〈0. 001, Asp：P〈0. 01 ）, since then though it was fluctuant, the concentration of Glu was still up to the basal level. 1 h after SAH the level of Asp rapidly declined to baseline, which was not significantly increased until 25 h after SAH （Asp：P〈0. 01）. Subsequently, it increased persistently. Conclusions The levels of Glu and Asp in the extracellular fluid of the cortex of rats with SAH have increase of different degree at different time. It suggests that Glu should play an important role during the early neuronal damage after SAH, and that Asp produce a mark effect during the late period.