玻璃体内注射谷氨酸导致大鼠视网膜Mǖller细胞内ERK1/2磷酸化水平增高

Intravitreal glutamate injection induces an increased phosphorylation of ERK1/2 in retinal Müller cells of rats

目的:观察大鼠玻璃体内注射谷氨酸后视网膜 M櫣ller细胞内ERK1/2分子的磷酸化水平,为探讨ERK1/2通 路的激活在谷氨酸毒性损伤视网膜时的保护作用提供形态学 证据.方法:SD大鼠18只,随机分为生理盐水对照组、谷氨酸 注射后3d组和7d组,每组6只.随机选取大鼠的一只眼进 行玻璃体内注射,实验组注射谷氨酸(375nmol)2μL,对照组 注射等量生理盐水,注射后3或7d后,取出眼球作冰冻切片, 采用免疫组化法显示视网膜中的含磷酸化ERK1/2的阳性结 构,用图像分析比较对照组和不同实验组的平均灰度值. 结果:注射谷氨酸7d组的视网膜M櫣ller细胞内ERK1/2表 达上调,其灰度值(97.00±2.21)比对照组灰度值(128.00± 3.23)和注射谷氨酸3d组的灰度值(126.00±4.12)均低 (P<0.05),与这两组的灰度值之间差异有显著性.结论:玻 璃体内注射谷氨酸导致大鼠视网膜M櫣ller细胞激活。

AIM: To analyze the changes of phospho-ERK1/2 in retinal Müller cells by using an intravitreal glutamate insult and to explore the neuroprotection role of activated (phosphorylated) ERK1/2 against glutamate cytotoxicity in retina. METHODS: A 2 μL of saline or glutamate (375 nmol) was injected into the random unilateral vitreous body for 3 d or 7 d in 18 SD rats. The rats were randomly divided into 3 groups: Control group (saline injections), glutamate injections 3 d group and glutamate injections 7 d group. The changes of the activated ERK1/2 were studied by immunohistochemical staining and computer-picture analytic system. RESULTS: After 7 d intravitreal glutamate insult, the activated phenotypes of retinal cells exhibited a hypertropic morphology and increased immunostaining for ERK1/2. By the staining pattern in shape and localization, the positive cells were presumed to be Müller cells. The gray level of glutamate injections 7 d group was the lowest among the 3 groups. The difference between glutamate injections 7 d group and other two groups was significant (P<0.05). CONCLUSION: Increased phosphorylated ERK1/2 in retinal Müller cells by using an intravitreal glutamate insult suggests that phospho-ERK1/2 plays an important neuroprotective role when retinal ganglion cells are injured by glutamate cytotoxity.