急性高眼压后大鼠视网膜谷氨酰胺合成酶的表达变化

EXPRESSION OF GLUTAMINE SYNTHETASE IN THE RAT RETINA FOLLOWING ACUTE INTRAOCULAR HYPERTENSION

为了探索谷氨酰胺合成酶在青光眼视网膜中的表达变化及其可能作用,本实验用急性高眼压模型,结合免疫组织化学染色和Western blot检测了急性高眼压后大鼠视网膜中谷氨酰胺合成酶的表达。结果显示:正常视网膜中,谷氨酰胺合成酶免疫组织化学染色主要见于Muller细胞胞体;0 d组中,Muller细胞胞体染色稍淡,而内网层中表达增加,且呈明显的点状分布; 1d组、3 d组中Muller细胞胞体染色进一步变淡,但内网层中呈现弥散染色。至再灌第7 d、14 d,Muller细胞胞体又出现浓的染色。平均灰度值显示:与正常组相比,0 d组中谷氨酰胺合成酶表达有增加但差异无显著性;1 d组中表达显著增加,3 d组、7 d组表达逐渐减少,至第14 d时基本恢复正常。Western blot显示谷氨酰胺合成酶为一分子量约为45 kD的单一蛋白带,与其它组相比,1 d组中表达显著增加。提示:急性高眼压导致的视网膜缺血再灌早期,Muller细胞中谷氨酰胺合成酶的快速重新分布和表达上调可能加速了胞外谷氨酸的代谢,对缺血再灌条件下的视网膜特别是节细胞起到保护作用。

To observe the expression change and potential role of glutamine synthetase(GS) in the glaucomatous retina, im-munohistochemistry and Western blot were used in an acute intraocular hypertension (AIH) model in this study. The results showed that GS immunoreactivity (GS-ir) was mainly localized in the Muller cell bodies in the normal retinas. Following AIH, bands of GS-ir were observed in the inner plexiform layer( IPL) of 0 d retina while mild decrease was found in the Muller cell bodies; intense and diffuse staining was observed m IPL of 1 d and 3 d groups. In contrast, the 7 d and 14 d groups showed similarity with the controls. Western blot analysis of retina from normal and AIH eyes revealed GS to be a single protein band with a molecular weight of 45 kD. GS level increased quantitatively in the 1 d group and then decreased gradually to control by day 14. The quick relocation and up-regulation of GS expression in the early stage of reperfusion suggests that GS may accelerate the metabolism of extracellular glutamate and thus protects the retina especially ganglion cells following AIH.