银杏苦内酯B对N-甲基-N-亚硝脲诱导的大鼠视网膜细胞凋亡的抑制作用

目的: 探讨银杏苦内酯B(GB)对N-甲基-N-亚硝脲(MNU)诱导的大鼠视网膜变性的影响及其机制。方法: 建立大鼠视网膜变性模型,应用TUNEL法检测光感受器细胞凋亡,RT-PCR法和免疫组织化学法分别检测MNU作用后不同时间大鼠视网膜中bcl-2和bax mRNA和蛋白的表达。结果: GB治疗组外核层细胞凋亡指数显著低于模型组(P<0.01)。MNU作用后12 h、1 d、2 d、3 d和5 d,bcl-2/bax mRNA模型组为0.36、0.15、0.29、0.42和0.64,GB治疗组为0.98、0.92、0.53、0.45和0.68,显著高于模型组(P<0.01)。GB治疗组Bcl-2蛋白在MNU给药后1 d表达最强,2 d阳性表达下降,3 d后阳性表达消失,模型组未见视网膜Bcl-2阳性表达;GB治疗组Bax蛋白表达显著低于模型组(P<0.01)。结论: 银杏苦内酯B能抑制MNU诱导的视网膜光感受器细胞凋亡,可能与上调Bcl-2的表达量,提高Bcl-2/Bax比值有关。

Protective mechanisms of ginkgolide B on rat retinal cell apoptosis induced by N-methyl-N-nitrosourea

AIM: To investigate the protective mechanisms of ginkgolide B(GB) on rat retinal degeneration induced by N-methyl-N-nitrosourea(MNU).METHODS: The rat retinal degeneration model was made.Photoreceptor cell apoptosis was measured by TUNEL assay.The expression of Bcl-2 and Bax in the different time points in the rat retina after treated with MNU was measured by RT-PCR and immunohistochemical methods.RESULTS: The outer nuclear layer cell apoptotic index in GB treatment group was significantly lower than that in model group(P<0.01).The bcl-2/bax mRNA ratios at scheduled time points of 12 h,1 d,2 d,3 d and 5 d after MNU injection in model control were 0.36,0.15,0.29,0.42 and 0.64,respectively,while the ratios in GB group were 0.98,0.92,0.53,0.45 and 0.68,respectively,larger than those in model control group(P<0.01).No Bcl-2 positive expression was detected at any scheduled time points after MNU injection in model control group.Strong positive Bcl-2 expression was detected in GB group 1 d after MNU injection,decreased at the 2nd day and disappeared at the 3rd day.Compared with model control group,the Bax expression in GB group was significantly decreased(P<0.01).CONCLUSION: Ginkgolide B effectively inhibits the apoptosis of photoreceptor cells.The mechanism of GB action may be related to the increase in the expression of Bcl-2 and the increase in the ratio of Bcl-2/Bax.