高血糖通过氧化损伤加重局灶性脑缺血再灌注神经元损伤

Hyperglycemia aggravated the focal brain ischemia/reperfusion injury through the neuronal oxidative damage

目的:探讨在高血糖加重脑缺血再灌注损伤中神经元氧化损伤的作用及机制。方法:将SD大鼠分为正常血糖脑缺血再灌注组(正常血糖组)、糖尿病高血糖脑缺血再灌注组(糖尿病组)以及假手术对照组(假手术组),通过线栓大脑中动脉制备局灶性脑缺血再灌注损伤模型,于再灌注后1,7和14 d分别进行组织学、8羟基脱氧鸟苷(8-hydroxy-2’deoxyguanosine,8-OHdG)免疫组织化学、NeuN和8-OHdG免疫荧光双标记,对比观察各组神经元的氧化损伤。结果:正常血糖组再灌注1 d脑组织出现明显水肿,糖尿病组较正常血糖组有所加重,出现较多的固缩神经元;再灌注7 d正常血糖组神经元固缩和脑水肿明显减少,糖尿病组仍可见少数神经元固缩和脑水肿;再灌注14 d正常血糖组神经元固缩和脑水肿消失,胶质细胞增加,糖尿病组可见轻度脑水肿。免疫组化和免疫荧光双标记提示,再灌注1 d,正常血糖组及糖尿病组8-OHdG阳性细胞和阳性神经元数量均明显增加,高血糖组8-OHdG阳性细胞数量和阳性神经元均明显高于正常血糖组(P<0.05)。再灌注7 d和14 d 8-OHdG免疫阳性细胞阳性神经元明显减少,但仍多于假手术组(P<0.05)。结论:糖尿病高血糖加重脑缺血再灌注损伤,神经元的氧化损伤是高血糖加重脑缺血再灌注损伤的重要方式之一。

Objective： To investigate the mechanism of hyperglycemia aggravating neuronal damage after the ischemia/ reperfusion （I/R） injury. Methods： SD rats were randomly assigned into normoglycemic focal cerebral I/R group （normoglycemic group）, diabetic hyperglycemic I/R group （diabetes group） and the sham groups. The focal cerebral I/R was induced by middle cerebral artery occlusion （MCAO） in rats. The immunohistochemistry and immunofluorescence stain of NeuN and 8-OHdG at 1 d,7 d and 14 d after reperfusion was comparably observed. Results： Significant cerebral edema was observed in normoglycemic group at 1 day after reperfusion, while worse cerebral edema, even neuronal pyknosis was appeared in diabetic group. The cerebral edema and neuronal pyknosis was decreased and disappeared in normoglycemic group at 7 d and 14 d after reperfusion, respectively. However, there was few neuronal pyknosis and edema in diabetic group. The number of 8-OHdG positive ceils and neurons was significantly increased at 1 d after reperfusion in both normoglycemic and diabetic rats compared with sham group （ P 〈 0.05 ）. More 8-OHdG positive cells and neurons were observed in diabetic rats compared with normoglycemic group （P 〈 0.05 ）. The number of 8-OHdG positive ceils and neurons was significantly decreased at 7 d, and 14 d after reperfusion in both normoglycemic and diabetic rats compared with sham group（P 〈 0.05 ）. Conclusion： Hyperglycemia aggravates the neuronal I/R injury, and the mechanism of oxi- dative damage of neurons might be involved.