The effect of dexamethasone on the expression of TGF ?_1 protein and the changes of microglia of adult rats' brain following permanent focal cerebral ischemia
- VernacularTitle:氟美松对大鼠局灶性脑缺血后小胶质细胞变化及转化生长因子?_1蛋白表达的作用
- Author:
Tao FENG
;
Ke ZHU
;
Xiaokun QI
- Publication Type:Journal Article
- Keywords:
Cerebral ischemia;
Dexamethasone;
Microglia;
Tranforming growth factor beta;
Carrier proteins
- From:
Chinese Journal of Neurology
1999;0(06):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study the expression of TGF ? 1 protein and the changes of microglia of adult rats' brain treated with dexamethasone following permanent focal cerebral ischemia as to elucidating the neurotoxic effect of dexamethasone. Methods The adult rat's models of permanent focal cerebral ischemia were established by permanent middle cerebral artery occlusion.One hour after ischemia experimental groups were treated with dexamethasone (0.5 mg?kg -1?d -1) where as the control groups were treated with saline. The size of infarct was detected by Q570 image analysis system. Immunohistochemistry and picture analyses were performed to observe the expression of TGF ? 1 protein. The microglia was demonstrated by histochemical staining with isolectin-B4.? Result Dexamethasone treatment after ischemia increases the infarct volume significantly. The expression of TGF ? 1 and the changes of microglia were mainly located at the border zone of the infarct. The accumulation of the isolectin-positive microglia began at 12 h,peaked at 2d, decreased at 5 d. The densities of microglia in the groups treated with dexamethasone after ischemia decreased significantly at 12 h,24 h and 3 d as compared with the control groups, and disappeared at 5 d.The expression time-course of TGF ? 1 protein was two-phase. The first peak of expression was at 6 h; the second was from 24 h to 72h. The significant decrease in expression of TGF? 1 protein in rats treated with dexamethasone was observed at 6 h,24 h and 72h compared with that of control group. Conclusion The exceeding inhibition of the response of microglia and the two-phase expression of TGF ? 1 protein at the border zone of infarct may play a role in the neurotoxic effect of dexamethasone on cerebral ischemia.
