AIM; To investigate the effects of dexmedetomidine on astrocytes in rats with focal cerebral ische-mia -reperfusion. METHODS: Sixty female SD rats, weighing 230～250 g, were randomly divided into sham operation group, ischemia - reperfusion group, dexmedetomidine preconditioning group 1 and dexmedetomidine preconditioning group 2. The model of middle cerebral artery occlusion (MCAO) was established by thread embolism of middle cerebral artery. In sham operation group, the carotid arteries were exposed without performing MCAO. In ischemia -reperfusion group, NS was injected intraperitoneally 30 min before focal cerebral ischemia - reperfusion. The rats in dexmedetomidine precondi-tioning group 1 and dexmedetomidine preconditioning group 2 received intraperitoneal injection of dexmedetomidine at doses of 20μg/kg and 40 μg/kg, respectively. The neurological scores were studied, and the pathological changes were observed under microscope with HE staining. The expression of glial fibrillary acidic protein (GFAP) and tumor necrosis factor a ( TNF - a) in astrocytes was detected by the methods of immunohistochemistry and immunoblotting 24 h after cerebral is-chemia - reperfusion. RESULTS: No neurological change was observed in sham operation group. The neurological defi-ciency scores in ischemia - reperfusion group were markedly higher than those in dexmedetomidine preconditioning group 1 and group 2 ( P < 0. 05 ) . Compared with sham operation group, the expression of GFAP and TNF - a in astrocytes and the level of GFAP increased significantly 24 h after focal cerebral ischemia - reperfusion. Pretreatment with dexmedetomidine significantly attenuated the expression of GFAP and reduced the infarct size and inflammation. CONCLUSION: Dexme-detomidine has a neuroprotective effect on focal cerebral ischemia - reperfusion injury by inhibiting the astrocytes.%目的:通过观察右美托咪定(DEX)对大鼠脑缺血再灌注损伤后星形胶质细胞的影响,探讨DEX对抗脑缺血再灌注损伤的作用及其机制.方法:采用大脑中动脉栓塞法建立大鼠局灶性脑缺血再灌注模型,将SD大鼠随机分为假手术组、单纯脑缺血再灌注组、DEX预处理1组(缺血前30 min腹腔给予DEX 20 μg/kg)及DEX预处理2组(缺血前30 min腹腔给予DEX 40 μg/kg).缺血再灌注24 h后,观察大鼠神经功能缺失评分,通过HE染色了解脑梗塞后脑组织的病理学变化,采用免疫组化和蛋白免疫印迹方法观察缺血后脑组织星形胶质细胞的变化.结果:DEX预处理能显著改善大鼠神经功能缺失评分,减小大鼠梗死面积,减少缺血区胶质纤维酸性蛋白(GFAP)阳性星形胶质细胞和肿瘤坏死因子α(TNF-α)阳性星形胶质细胞,降低GFAP表达水平.结论:DEX对缺血再灌注损伤的脑组织具有保护作用,其作用机制可能与抑制星形胶质细胞激活有关.
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