N-乙酰半胱胺酸对大鼠挫伤性视网膜病变的保护作用

目的:研究凋亡相关基因Bcl-2/Bax在大鼠挫伤性视网膜病变中的表达,以及N-乙酰半胱氨酸(N-acetyl-cysteine,NAC)对其表达的影响。方法:自由落体法制作视网膜挫伤模型。将SD大鼠随机分为正常组6只、模型组24只及治疗组24只。每组按挫伤后不同时间段分为1,3,7,14d,每个观察时段6只大鼠。HE染色光镜观察视网膜组织学变化,应用SABC免疫组织化学法检测大鼠视网膜挫伤后视网膜组织Bcl-2/Bax蛋白表达的变化。结果:挫伤性视网膜病变的损害主要集中在神经纤维层。挫伤后视网膜组织水肿,细胞紊乱,胞浆空泡样变,视网膜组织变薄,细胞丢失。NAC治疗组视网膜水肿程度有所改善,细胞紊乱,胞浆空泡样变,细胞丢失有所恢复。正常组及NAC治疗组视网膜组织Bax均未见表达,Bcl-2低表达。视网膜挫伤后1d时Bax表达开始增多,3d强阳性表达,7d表达有所减少,14d时表达进一步减少。Bcl-2低表达,未见明显变化。NAC治疗组各观察指标变化趋势基本与视网膜挫伤组相似,但表达明显减弱,两组相比较,于挫伤后1,3d和7d时差异有统计学意义(P<0.05)。Bcl-2在各时段的表达均较模型组有所增强,两组相比较,于挫伤后1,3d和7d时差异有统计学意义(P<0.01)。结论:在大鼠挫伤性视网膜病变中,NAC能够改善视网膜组织病理学损害并通过调节Bcl-2/Bax蛋白表达而抑制细胞凋亡,对视网膜挫伤具有保护作用。

The protective effect of N-acetyl-cysteine on rats traumatic retinopathy

AIM: To study the expression of Bcl-2/Bax in contusion of the rat retina and the effect of N-acetyl-cysteine(NAC)on it.

METHODS: The animal model of retinal injury was created by a free falling iron bar hitting the rat cornea. The rats were divided into normal group(n=6), contusion group(n=24)and treatment groups of NAC(n=24)randomly. After retina contusion, the latter two groups were subdivided into 1 day, 3 days, 7 days and 14 days group; there were 6 rats in each observation period. Structural changes of retina were observed with light microscope, and the expression of Bcl-2/Bax was observed by immunohistochemistry.

RESULTS: In the contusion of the rat retina, retinal damage was concentrated in sensory layer. RGC layer, inner nuclear layer, and outer nuclear layer cells were obviously observed. After contusion, retinal tissue edema, cell disorder, cytoplasm vacuolated changes, thinning of retinal tissue, and cell loss were began to appear. No expression of Bax was found in normal group and treatment group, and low expression of Bcl-2 was observed. Most of Bax positive cells had expression at 1 day after contusion injury in contusion group, and then increased obviously at 3 days, and decreased at 7 days and much further at 14 days, and Bcl-2 positive cells had expression at a low stage. Treatment group had the same trend with the contusion groups in each index, but the expressive intensity of each period weakened in evidence. There were significant differences between two groups at 1 day,3 days and 7 days after contusion(P<0.05). The expression of Bcl-2 in each period of time was increased. Compared the two groups with 1 day, 3 days after contusion and 7 days had a significant difference(P<0.01 ).

CONCLUSION:In the contusion of the rat retina, NAC can improve the retina damage, and may protect the retinal tissue from contusion injury by regulating Bcl-2/Bax protein expression.