实验性糖尿病大鼠海马星形胶质细胞形态和凋亡的研究

Histological morphology and apoptosis of astrocytes induced by hippocampus of experimental diabetic hyperglycemia in rats

目的：研究糖尿病高血糖大鼠海马星形胶质细胞形态和凋亡改变。方法：采用链脲佐菌素（STZ）诱导Ⅰ型糖尿病SD大鼠模型,并以正常SD大鼠作对照。分别于1、2、4周和8周用组织学、免疫组织化学、免疫荧光和Western Blot等方法对比研究糖尿病高血糖对大鼠海马区星形胶质细胞形态和凋亡的作用。结果：与正常对照比较,大鼠糖尿病高血糖1~2周,脑组织结构基本正常,海马区固缩神经元偶见,4~8周固缩神经元数明显（P〈0.05）,出现轻微脑水肿,星形胶质细胞胞体轻度肿胀;免疫荧光和免疫组织化学检测显示,糖尿病高血糖1~2周,星形胶质细胞胞体增大和突起增粗,4~8周时突起增粗变长,星形胶质细胞数量减少（P〈0.05）;Western Blot结果表明,大鼠糖尿病高血糖4~8周时,脑组织胶质原纤维酸性蛋白（GFAP）含量明显升高（P〈0.05）;免疫组化双标显示,糖尿病高血糖大鼠1~2周偶见cleavedcaspase-3阳性标记的星形胶质细胞（P〈0.05）,4~8周海马区双标阳性细胞数明显增多（P〈0.01）。结论：大鼠糖尿病高血糖早期对星形胶质细胞可能有激活作用,而持续的糖尿病高血糖则可抑制海马区星形胶质细胞,并可能导致星形胶质细胞凋亡。

Objective： To investigate the histological morphology and apoptosis of astrocytes induced by hippocampus of experimental diabetic hyperglycemia in rats. Methods：Type 1 diabetes mellitus SD rat model was induced by injection of streptozotocin （ STZ）, and the normal SD rats were used as the control group. The effects of diabetic hyperglycemia on the morphology and apoptosis of astrocytes in hippocampus of rats were measured by bistology, immunohistochemistry, immu- nofluorescence and Western Blot in 1, 2, 4, and 8 weeks, respectively. Results： Compared with the normal control, dia- betic hyperglycemia in rats, the structure of brain tissue was normal, and the fixation neurons were occasionally seen in the hippocampus at 1 - 2 weeks. At 4 - 8 weeks, the number of the pyknotic neurons increased significantly（ P 〈 0.05 ）, and it was found that mild cerebral edema was found in the astrocytes. By immunofluorescence and immunohistochemistry assay, the cell bodies and growth of astrocytes were increased in the diabetic rats at 1 - 2 weeks, and number of the cells was decreased at 4 - 8 weeks （ P 〈 0.05 ）. By Western Blot, the expression of glial fibrillary acidic protein （GFAP） in brain tissue of rats with diabetes mellitus was significantly higher than that the control group at 4 - 8 weeks （P 〈 0.05 ）. Immunohistochemically double staining showed, in diabetic hyperglycemia rats at 1 -2 weeks there was cleavedcaspase-3 positive staining astroglial cells （ P 〈 O. 05 ）, and the number of positive cells in hippocampus were increased significantly at 4 - 8 weeks （P 〈 0.01 ）. Conclusion ： The results show that activation of astrocytes induced by diabetic hyperglycemia in rats is could occur at early stages, and persistent diabetes hyperglycemia may inhibit the astrocytes in the hippocampus, and lead to the apoptosis of astrocytes.