促红细胞生成素对视网膜缺血再灌注神经元凋亡和caspase-2表达的影响

EFFECT OF ERYTHROPOIETIN ON NEURONAL APOPTOSIS AND CASPASE-2 EXPRESSION AFTER RETINAL ISCHEMIA-REPERFUSION INJURY

为研究促红细胞生成素(erythropoietin,EPO)预处理对视网膜缺血后caspase-2蛋白表达的影响,并探讨其对视网膜缺血保护的可能机制,我们采用升高眼内压的方法制作实验性视网膜缺血大鼠模型。将Wistar大鼠随机分为正常组、生理盐水组及EPO组。缺血前24h,生理盐水组腹腔注射生理盐水,EPO组注射重组人促红细胞生成素(rhEPO)5000U/kg。观察缺血再灌注后不同时间段生理盐水组及EPO组视网膜组织学变化、TUNEL检测及caspase-2蛋白的表达。结果发现:(1)视网膜缺血再灌注各时间段,H.E.染色EPO组大鼠视网膜内层厚度均较生理盐水组厚,且内核层细胞数多于生理盐水组(P<0.01);(2)TUNEL法凋亡细胞测定显示,正常组无阳性细胞,缺血再灌注24h,EPO组内核层的凋亡细胞比生理盐水组少(P<0.01);(3)caspase-2蛋白表达的测定显示,正常组无阳性细胞,EPO组及生理盐水组在缺血再灌注12h检测到caspase-2蛋白阳性表达,但EPO组阳性蛋白表达量比生理盐水组少(P<0.01)。以上结果提示:EPO预处理可以促进视网膜缺血再灌注后细胞的存留,减少细胞凋亡,caspase-2蛋白表达的抑制可能参与了这种保护机制。

To observe the effect of erythropoietin（EPO） pretreatment on caspase-2 expression after retinal ischemia and explore the neuroprotection mechanism of EPO. The Wistar rat model of experimental retinal ischemia was made by increasing the intraocular pressure. The rats were divided into normal group, saline group and EPO group randomly, rhEPO at 5000 U/kg or normal saline control was administered i.p. 24 hours before retinal ischemia. The histological changes, TUNEL detection and the expression of caspase-2 protein in retina at different time-points after reperfusion were observed. The results showed that ： （ 1 ） The thickness of the inner retina and the INL cell number of EPO group were bigger than those of the saline group after H. E. staining during all the post-reperfusion stages（ P 〈 0.01 ） ; （2） No TUNEL-positive cell was seen in the normal group, and there were less apoptosis cells（ P 〈 0.01 ）in EPO group than those in ischemia group at 24 hours after reperfusion; （3） The expression of caspase-2 protein at 12 h after reperfusion between EPO group and saline group was significantly different （ P 〈 0.01 ）. These results suggest that EPO pretreatment can promote neuronal viability, inhibit the apoptosis of neurons after retinal ischemia, and the down-regulating of caspase-2 expression might contribute to the protective mechanism.