重组人促红细胞生成素对高糖视网膜Müller细胞谷氨酰胺合成酶表达的影响

摘要

Objective To investigate the effect of recombinant human erythropoietin (rhEPO) on the expression of glutamine synthetase (GS) of cultured rat retinal Müller cells in high glucose environment in vitro.Methods Mtüller cells were isolated from retinas of 10 Sprague-Dawley rats at postnatal day three to five by trypsin digestion,and were randomly divided into six groups,including normal control group,high glucose group,high glucose +5 U/ml rhEPO group,high glucose+ 10 U/ml rhEPO group,high glucose+ 20 U/ml rhEPO group,high glucose+40 U/ml rhEPO groups.After 48 hours,the apoptosis of retinal Müller cells were assayed by terminal transferase-mediated DNA end labelling assay,and the expression levels of GS protein were detected with semi-quantitative immunocytochemistry.Results Compared with the normal control group,the cell viability and GS protein were reduced while the cell death increased in Müller cells cultured in high glucose,the difference was statistically significant (t =27.4,P ＜ 0.01).Compared with the high glucose group,rhEPO treatment reduced the apoptotic Müller cells (t=857.2,2 374.6,2 473.2,2 537.7; P＜0.01),induced the expression of GS proteins (t=3.2,18.0,22.5,26.4; P＜0.05).Conclusions rhEPO can protect Müller cells from apoptosis under high glucose condition.The mechanism may be related to its function to up-regulate the GS protein expression,promote glutamic acid cycle,and reduce the excitotoxicity effects of high concentration of glutamate.%目的 观察体外培养大鼠视网膜Müller细胞在高糖培养环境下谷氨酰胺合成酶(GS)的表达变化,探讨重组人促红细胞生成素(rhEPO)对其表达的影响及作用机制.方法 出生后3～5 d新生Sprague-Dawley大鼠10只,摘除眼球分离视网膜,经胰酶消化后分离纯化视网膜Müller细胞.并将其随机分为正常对照组、高糖培养组、高糖+5U/ml rhEPO组、高糖+10 U/ml rhEPO组、高糖+20 U/mlrhEPO组、高糖+40 U/ml rhEPO组.48 h后原位缺口末端标记法检测高糖及不同浓度rhEPO对视网膜Müller细胞凋亡的影响；免疫细胞化学法半定量检测高糖组在不同浓度rhEPO干预下视网膜Müller细胞GS蛋白的表达水平.结果 与正常对照组比较,高糖培养组视网膜Müller细胞活性下降,细胞大量凋亡,GS蛋白表达下降,差异有统计学意义(t=27.4,P＜0.0l).与高糖培养组比较,不同浓度rhEPO处理组凋亡细胞随着rhEPO浓度的增加显著性减少,差异有统计学意义(t=857.2、2 374.6、2 473.2、2 537.7,P＜0.01),GS蛋白的表达显著性升高,差异有统计学意义(t=3.2、18.0、22.5、26.4,P＜0.05).结论 rhEPO对高糖作用下视网膜Müller细胞的凋亡具有保护作用,并可上调高糖损伤细胞内下降的GS蛋白表达水平；促进谷氨酸循环,有效降低高浓度谷氨酸的兴奋性毒性作用,可能是其抗高糖损伤的保护机制之一.