胰岛素对大鼠脑缺血再灌注后Bcl—2表达及细胞凋亡的影响

The effect of insulin on the expression of Bcl-- 2 and the neuronal apoptosis in rats after cerebral ischemia-- reperfusion

目的探讨胰岛素对大鼠脑缺血再灌注后Bcl-2表达及细胞凋亡的影响。方法将动物随机分为假手术组、缺血组及干预组，参照Zea Longa线栓法建立大鼠左侧大脑中动脉闭塞（middle cerebral artery occlusion，MCAO）再灌注模型，干预组大鼠在脑缺血即刻给予胰岛素及葡萄糖腹腔注射，分别在左侧MCAO2h再灌注不同时间点断头取脑，脑皮质神经元Bcl-2的表达通过免疫组化法来测定，并采用TUNEL法原位标记DNA片段，检测TUNEL阳性细胞的变化。结果缺血组大鼠脑皮质Bcl-2的表达较假手术组显著增强（P〈0．01），TUNEI。阳性细胞数较假手术组显著增多（P〈0．01）；给予胰岛素处理后，Bcl-2的表达较缺血组显著增强（P〈0．01），TUNEL阳性细胞数较缺血组明显减少（P〈0．01），但两者均显著高于假手术组（P〈0．01）。结论短暂的脑缺血再灌注可导致脑皮质神经元中Bcl-2的表达增加，抗细胞凋亡；胰岛素可上调脑皮质神经元中Bcl-2的表达，发挥神经保护作用。

Objective To investigate the effect of insulin on the expression of Bel--2 and the neuronal apoptosis in rats after cerebral isehemia--reperfusion. Methods 78 male Sprague--Dawley rats were randomly divided into 3 groups： sham operation group （sham）, cerebral isehemia group （CI） and insulin intervention group （IN）. Focal cerebral ischemia on left side was induced by middle cerebral artery occlusion （MCAO） according to Longa＇s methods. Insulin and glucose was injected into the enterocoelia immediately post- occlusion in insulin intervention group. Reperfusion began 2hrs after the left middle cerebral artery occlusion. At the prescriptive time, rats were killed and brains were harvested. Immunohisto--chemistry method was used to detect the expression of Bcl--2 and terminal deoxynucleotidyl transferase--mediated dUTP nick end labeling（TUNEl.） was used to calculating TUNEL positive neuron. Results The expression of bcl--2 was significantly higher in IN group than that in sham （P 〈 0.01） and CI group （P 〈0.01）. The expression of bcl--2 was significantly increased in CI group than that in sham group （P〈 0.01）. The TUNEL positive neurons was significantly higher in CI group than that in sham （P 〈0.01）. But the TUNEL positive neurons was significantly decreased in IN group than that in CI group （P 〈 0.01） although higher than sham group （P〈 0.01 ）. Conclusions The transient cerebral isehemia--reperfusion induced neuronal apoptosis and overexpression of bcl--2 to protect neurons from damage. Insulin protected neurons through up--regulating the expression of Bcl-2.