大鼠星形胶质细胞在高血糖脑缺血再灌注损伤中的变化

目的:探讨星形胶质细胞在高血糖脑缺血再灌注损伤中的变化规律。方法:采用链脲佐菌素(STZ)诱导Ⅰ型糖尿病高血糖大鼠模型,通过双侧颈总动脉夹闭联合股动脉放血法建立全脑缺血再灌注模型,应用组织学、免疫荧光、组织化学及Western Blot方法,对比观察糖尿病高血糖脑缺血再灌注组(简称糖尿病组)与正常血糖脑缺血再灌注组(简称正常血糖组)在脑缺血15 min、再灌注1 h和6 h大脑额叶皮质区神经元、星形胶质细胞组织学变化及GFAP的表达。结果:正常血糖组再灌注1 h脑组织出现轻度水肿;再灌注6 h脑水肿加重,出现神经元固缩;再灌注1 h,糖尿病组病变与正常血糖组基本相同,再灌注6 h脑水肿加重,固缩神经元进一步增加。再灌注1 h和6 h,糖尿病组Nissl体平均光密度值明显低于正常血糖组(P<0.05)。脑组织GFAP免疫荧光检查可见,再灌注6 h正常血糖组GFAP免疫阳性细胞明显增加。糖尿病组再灌注1 h和6 h,出现GFAP阳性星形胶质细胞数目增加(P<0.05),胞体显著增大,突起增长、增粗。Western Blot结果可见,糖尿病组GFAP的表达明显高于正常血糖组。结论:糖尿病高血糖脑缺血再灌注能够加重神经元损伤,星形胶质细胞出现更明显的数量增加和GFAP表达。

Changes of astrocytes in cerebral ischemia and reperfusion injury under hyperglycemia of rat

Objective:To detect changes of astrocytes in rat brain after ischemia and reperfusion under hyperglycemia.Methods: Type 1 diabetic hyperglycemia rat model was induced by injection of streptozotocin(STZ).Forebrain ischemia was induced by clamping bilateral common carotid arteries and bleeding hypotension.For both of hyperglycemic brain ischemia group(diabetes group) and normoglycemic brain ischemia group(normoglycemic group),histological changes of neurons and astrocytes and expression of glial fibrillary acidic protein(GFAP) in astrocytes at frontal cortex were detected by pathohistology,immunofluorescence and Western Blot after 15 minutes of brain ischemia,and 1 or 6 hours of recirculation.Results: A mild cerebral edema was observed in normoglycemia group at 1 hour of reperfusion.Worse cerebral edema,even neuronal pyknosis was appeared followed 6 hours of reperfusion.Hyperglycemic ischemia increased cerebral damage of 6 hours of reperfusion comparing to normoglycemia group.Comparing with the normoglycemia,the optical density of Nissl bodies in diabetes rats was significantly decreased at 1 and 6 hour of reperfusion(P<0.05).By immunofluorescence staining we found that numbers of GFAP-positive cells was increased at 6 hours of reperfusion in both normoglycemic and diabetic rats.Hyperglycemic ischemia increased GFAP expression(P<0.05).Enlarged cell body,lengthened and thicken process of astrocytes were detected in the diabetes group at 1 and 6 hours of reperfusion.Western Blot results for GFAP protein confirmed the above results.Conclusion: Diabetic hyperglycemia could aggravate brain ischemia and reperfusion induced cerebral damage,and increase astrocytes cell number and GFAP expression.