急性脑缺血时缺血对侧血流动力学动态变化的实验研究

Experimental Study on the Hemodynamic Changes of the Counterpart of the Cerebral Ischemic Lesion in Acute Cerebral Ischemia

目的:研究急性脑缺血时缺血对侧脑组织的血流动力学变化。方法:采用1∶1配对方法,实验组6只兔成功制作急性局灶性脑缺血模型,对照组6只行假手术。采用GE Lightspeed16MSCT,在基础灌注后于栓塞后不同时间点进行CT灌注。在完成缺血12h CT灌注扫描后,断头取脑,进行TTC染色和Bcl-2免疫组织化学染色。测量不同时间点缺血对侧相同区域灰质和白质区参数值并与对照组相同区域比较;实验组两侧大脑半球免疫组化切片进行Bcl-2阳性细胞计数,并与对照组比较。结果:TTC染色示实验组缺血侧脑组织出现白色的梗死区,缺血对侧和对照组的两侧大脑半球均未见梗死区。实验组缺血侧、缺血对侧、对照组的Bcl-2阳性表达细胞数分别为25±2个/HP、13±4个/HP和1±1个/HP(x±s),两两间差异均有显著统计学意义(P<0.001)。实验组缺血对侧CBV在缺血1h内呈轻度上升趋势,1h后下降,处于一个低水平,8h后又轻度上升;CBF在缺血12h内呈逐渐下降趋势。实验组的缺血对侧CBV或CBF在脑缺血12h内的动态变化与对照组有显著性差异(P<0.001),缺血对侧灰白质之间的动态变化亦有显著差异(P<0.001)。结论:急性脑缺血时缺血对侧脑组织的血流呈可逆性下降,且引起受累脑细胞凋亡。

Objective：To investigate the hemodynamic changes of the counterpart of the ischemlc brain in acute cerebral ischemla. Methods：In our experiment, focal cerebral ischemia models were successfully established in 6 rabbits （designated as experimental group）,a sham operation was undergone in 6 other rabbits （designated as control group）. All of the CT scans were performed with a GE Lightspeed 16 multisllced CT scanner. Following the baseline scans, further CT perfusion scans were performed at the same sites of the brain every hour till 12 hours since the ischemic process induced by embolus delivery. Then, the heads of the rabbits were cut down and the brains were taken off for study. The brains were stained with TTC and studied the expression of Bcl-2 protein with immunohistochemical technique. CT perfusion parameters of the gray and white matter of the counterparts of the ischemic lesions at different time-points were measured and compared with those relative data obtained from the control rabbits. The Bcl-2 positive cells were counted. Results：On the TTC maps, except the ischemic side of brain of the experimental group, no white areas were found in their counterparts and the brains of the control group. The counts of Bcl-2 positive cells of the ischemic brain parenchyma, those of their counterparts and of the control group were 25 ±2/HP, 13 ± 4/HP and 1 ±1/HP （x^-± s） respectively. Marked statistic difference was found among them （P〈0. 001）. In comparison with those of the control group,both CBV and CBF were lower in the counterparts of the experimental group. In the experimental group, there was an initial and mild increase of CBV of the counterparts,then a decrease was found and finally a mild increase happened again. CBF of the counterparts decreased gradually within 12 hours since ischemia. Distinguished statistic differences in both CBV and CBF were found between counterparts of the experimental and control groups. The hemodynamic changes of gray matter were not the same as those of the white matter （P〈0. 001）. Conclusion：CBV and CBF of counterparts of the ischemic hemispheres reversibly decreased at acute phase, however,some of the involved brain cells would have been led to apoptosis.