暗饲养对视神经横断后SD大鼠视网膜谷氨酰胺合成酶表达的影响

Effect of dark rearing on expression of glutamine synthetase in retina of SD rat after optic nerve transection

目的探讨视神经横断后Müller细胞在改善视网膜节细胞轴突再生微环境及其对光信号传递突触的保护作用。方法实验建立视神经横断模型,随机分成正常昼夜循环组及黑暗饲养组,用免疫组织化学及Western blot法检测视神经横断后,SD大鼠在正常昼夜循环条件及黑暗条件下饲养时视网膜谷氨酰胺合成酶随饲养时间延长的表达变化;Nissl染色法观察相应视网膜节细胞的形态结构改变。结果正常昼夜循环饲养的大鼠视网膜谷氨酰胺合成酶的表达于视神经横断后持续减少,5 d时达最低值;暗饲养的大鼠视网膜谷氨酰胺合成酶的表达于视神经横断后3 d时最低,5~7 d时持续增加。Nissl染色显示暗饲养组大鼠视网膜节细胞14d时存活较多。结论正常昼夜循环条件视神经横断后Müller细胞谷氨酰胺合成酶的表达呈应激性反应,暗饲养能在突触溃变关键期维持视网膜内谷氨酰胺合成酶的表达强度。

【Objective】To explore the effect of Müller cells on improving the microenvironment of axonal regeneration of retinal ganglion cell（RGC） and protecting the synapsis of optical signal transduction after optic nerve transection. 【Methods】The optic nerve transection rat models were established, and then randomly divided into normal circadian cycle group and darkness rearing group. Finally, the expression of retinal glutamine synthetase（GS）in SD rats reared in the normal circadian cycle conditions and dark conditions after optic nerve transection was detected by immunohistochemistry assay and Western blot. And the number of retinal ganglion cells was counted and the morphological changes of retinal ganglion cells were observed after Nissl staining. 【Results】The retinal GS expression decreased and reached the lowest value on 5th d after optic nerve transection in the normal circadian cycle reared rats; and that in the dark reared rats reached the lowest value on 3rd d after optic nerve transection, and then increased on 5th to 7th d after optic nerve transection. Nissl staining showed that the number of RGCs was larger in the dark reared rats than in the normal circadian cycle reared rats. 【Conclusions】The expression of GS in Müller cells is in a stress reaction stage after optic nerve transection in normal circadian cycle conditions. Dark rearing can maintain the GS expression intensity within the critical period of synaptic degeneration in retina.