Bcl-2、Bax在百草枯诱导大鼠视网膜损伤中的表达

Expression of Bcl-2 and Bax in rat retina withretinal injury induced by paraquat

目的观察百草枯对SD大鼠视网膜损伤的作用及对Bcl-2、Bax表达的影响,并探讨Bcl-2、Bax在百草枯诱导的视网膜细胞凋亡中的作用及意义。方法将大鼠随机分成对照组和模型组,对照组玻璃体腔注射0.1 mol.L-1 PBS,模型组玻璃体腔注射一定浓度的百草枯,分别在12 h、1 d、2 d、5 d处死动物,HE染色观察视网膜的损伤程度,TUNEL法检测视网膜细胞的凋亡情况,同时采用Western blot检测Bcl-2、Bax蛋白的表达。结果①HE染色观察随着时间的增加,外核层逐渐变得稀疏并观察到核固缩,内核层可观察到核固缩,神经节细胞出现空泡样,5 d时内丛状层消失,外核层内核层紊乱。②TUNEL法检测凋亡结果:对照组没有发现凋亡阳性细胞,PQ可以诱导视网膜细胞凋亡,2 d凋亡指数达到高峰③Western blot结果:百草枯诱导的大鼠视网膜损伤可上调Bcl-2的表达,在1 d时达到高峰,与对照组相比差异有显著性(P<0.01),2 d开始下降;同时上调Bax的表达,在2 d时达到高峰,5 d时下降,各组之间差异均具有显著性(P<0.01);下调Bcl-2/Bax的比值,在2 d时达到最低,与对照组相比差异有显著性(P<0.01),到5 d时升高,与对照组比仍较低(P<0.01)。结论百草枯诱导了视网膜细胞的凋亡,可能是通过调节Bcl-2和Bax的表达来诱导视网膜细胞的凋亡,Bcl-2/Bax也与凋亡的发生密切相关。

Aim To investigate the effect of paraquat-induced retinal injury on Bcl-2 and Bax protein expression in SD rats and discuss their role and significance in apoptosis of retinal cells induced by paraquat（PQ）.Methods Rats were divided into 5 groups randomly,including normal control（NC）group and PQ model control groups.NC group was intravitreously injected with 0.1 mol·L-1 PBS,while PQ model groups were intravitreously injected with a concentration of paraquat.The animals were sacrificed and eyeballs were extracted 12 h,1 d,2 d,5 d after PQ intravitreous injection.The degree of retinal injury was observed with light microscope.Retinal cell apoptosis was determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling（TUNEL）.Simultaneously,expression of Bcl-2 and Bax proteins in NC group and every model group were detected by Western blot.Results ① The outer nuclear layer became raritas gradually.Pyknosis could be observed in inner nuclear layer.Vacuolated ganglion cells were also observed.Besides,the inner plexiform layer disappeared,inner nuclear layer and outer nuclear layer became in disorder on 5 d after PQ injection.② The result of apoptosis detected by TUNEL：NO apoptotic cells in NC group,while PQ could induce apoptosis in retinal cells,and the apoptotic index（AI） peaked on 2 d after PQ injection ③ The result of Western blot：The injury of retinal cells induced by PQ up-regulated the Bcl-2 expression,which peaked on 1 d,significantly compared with NC group（P0.01）,and reduced on 2 d;simultaneously significantly up-regulated the expression of Bax,which peaked on 2 d,and down-regulated on 5 d（P0.01）;when compared with the value of Bcl-2/Bax down-regulated on 12 h and was the lowest on 2 d（P0.01）.The value elevated on 5 d,but it was still lower than that of NC group（P0.01）.Conclusions PQ can induce apoptosis in retinal cells via regulating the expression of Bcl-2 and Bax,Bcl-2/Bax is closely related to the occurrence of apoptosis.