不同剂量IGF-2对脑缺血再灌注损伤的保护作用

目的胰岛素样生长因子-2（Insulin-Like Growth Factor-2,IGF-2）对脑缺血再灌注损伤具有神经保护作用[1],S100B蛋白是神经胶质细胞分泌的蛋白质,反映神经细胞损伤的标记物,目前国内外尚无报道给予IGF-2后脑缺血灌注区S100B蛋白的动态观察,本研究通过观察不同剂量IGF-2对缺血性卒中脑缺血再灌注区不同时间点S100B蛋白表达的动态变化,研究其对局灶性脑缺血再灌注损伤影响的量效关系。方法取66只SD大鼠建立局灶性脑缺血再灌注模型,随机分成假手术对照组（n=6）、脑缺血再灌注组（n=15）、IGF-2治疗组（低剂量组n=15、中等剂量组n=15、高剂量组n=15）,按再灌注时间分为3个亚组,亚组15只（12h组5只、1d组5只、3d组5只）;脑缺血1h后开始再灌注。免疫组化采用SABC法,检测脑缺血不同时间大脑皮层S100B蛋白,用原位末端标记技术检测各组大鼠大脑皮层缺血中心和周围区神经细胞凋亡的表达。结果凋亡检测结果显示,脑缺血再灌注损伤组与假手术对照组比较凋亡细胞数明显增多（P〈0.05）;与脑缺血再灌注组相比,IGF-2中等剂量治疗组与高剂量组凋亡细胞数明显减少（P〈0.05）,IGF-2低剂量组与脑缺血再灌注组比较无统计学意义（P〉0.05）。免疫组化检测结果显示,脑缺血再灌注损伤组与假手术对照组比较S100B蛋白表达明显增多（P〈0.05）;与脑缺血再灌注组相比,IGF-2中等剂量治疗组与高剂量组S100B蛋白表达明显减少（P〈0.05）,IGF-2低剂量组S100B蛋白表达无统计学意义（P〉0.05）;中等剂量组与高剂量组在凋亡细胞与S100B蛋白表达方面比较,差异均有统计学意义。结论 IGF-2可促进S100B蛋白表达减少,凋亡细胞数明显减少,可能是IGF-2产生脑保护机制的原因之一;推测IGF-2治疗局灶性脑缺血再灌注脑损伤存在量效关系,随治疗剂量增加可能疗效改善。

Protective mechanism of the different doses of insulin-like growth factor-2 for focal cerebral ischemia reperfusion injury

【Objective】IGF-2 plays an important role in protecting cerebral ischemic reperfusion injury,S100B protein is a marker of nerve cell Injury,secreted by gliocyte,Now no report is about the dynamic observation of S100B protein after the different doses of IGF-2 supplyed after cerebral ischamic reperfusion injury home and abroad.The research is to study the possible mechanism of the effects of the different doses of IGF-2 towards focal cerebral ischamic reperfusion Injury by the dynamic observation of s100B protein at the different time after the cerebral ischamic reperfusion Injury.【Methods】66 SD rats were operated to establish focal cerebral ischamic reperfusion Injury model and were divided into 3 groups randomly： imitational operation control group（6 rats）,cerebral ischemic reperfusion Injury group（15 rats）,treatment of IGF-2 group（low dose group 15 rats、moderate dose group 15 rats、high dose group 15 rats）.All these 3 groups were divided into 3 subgroups（12h、1day、3day）.One hour after cerebral ischemia,Cerebral ischamic reperfusion is finished.Immunohistochemistry were used to observe apoptosis of neuronal cells at the central and around the focal cerebral ischemia and detect the expression of S100B protein. 【Results】The result showed that compared with imitational operation control group,the expression of S100B protein in ischemic reperfusion injury group increased greatly（p0.05）;compared with ischemic reperfusion injury group,the expression of S100B protein in the moderate and high dose of treatment group decreased greatly（p0.05）,but no statistical significance was found in low dose group;By the Tunel detection we can see that the number of neuronal cells＇ apoptosis in the moderate and high dose of IGF-2 treatment group decreased clearly compared with ischemic reperfusion injury group（p0.05）;Compared with imitational operation control group,the expression of S100B protein in ischemic reperfusion injury group increased greatly（p0.05）;the defference between the moderate and high dose of treatment group has obvious statistical significance in the expression of S100B protein and the number of neuronal cells＇ apoptosis（P﹤0.01）.【Conclusion】IGF-2 can not only reduce the number of neuronal cells＇ apoptosis and the expression of S100B protein greatly,which should be presumed one of its brain protective mechanisms;We Speculated that dose-effect relationship exists in IGF-2 treatment of focal cerebral ischemia-reperfusion brain injury,the therapy efficacy may be improved with the dose increased.