Caspase-9抑制剂对RCS大鼠感光细胞凋亡抑制作用的研究

目的：采用Z-LEHD-FMK进行体内实验，观察caspase-9抑制剂对RCS大鼠感光细胞凋亡的抑制作用。方法：32只 18 d RCS大鼠随机分4组，检查ERG后随机选择一眼为实验眼给予玻璃体内注射Z-LEHD-FMK 4 μg，对侧眼给予4 μg 2%DMSO作对照。各组分别在术后2 d、7 d、12 d、17 d行ERG检查，然后摘取双眼球，石蜡切片行HE染色及感光细胞凋亡的TUNEL检测，透射电镜观察视网膜超微结构。结果：实验眼注药后 7 d ERG b波振幅达到最大(137.35±7.41)mV，17 d时b波振幅为(57.91±9.27)mV，对照眼7 d及以后各组ERG接近熄灭型；实验眼注药后12 d视网膜外颗粒层才开始出现凋亡阳性细胞，17 d更明显，对照眼强荧光的凋亡阳性细胞在术后7 d已经很明显；光镜下注药后17 d实验眼感光细胞外颗粒层细胞数尚保持有7-8层，对照眼仅余下2-4层细胞，视网膜厚度变薄；透射电镜下实验眼注药后17 d可见部分感光细胞胞核、核仁固缩，对照眼从术后 7 d 开始见感光细胞呈现凋亡改变。结论：Z-LEHD-FMK能够延缓RCS大鼠感光细胞凋亡，合适的caspases抑制剂在适宜的时机应用对视网膜感光细胞凋亡具有一定的抑制作用。

Inhibition of photoreceptor apoptosis in RCS rats by caspase-9 inhibitor

AIM: To observe the apoptosis inhibition of photoreceptor in Royal College of Surgeons (RCS) rats by Z-LEHD-FMK in order to evaluate the role of caspase-9 in photoreceptor apoptosis.METHODS:4 μg Z-LEHD-FMK were used to inject into vitreous of one eye of 32 RCS rats with age of 18 days. As a control, the same dose of 2% dimethyl sulfoxide (DMSO) was injected into another eye. Before injection, 8 rats were received ERG examination used for control of pre-injection and all the rats received ERG examination again at the 2nd, 7th, 12th and 17th post-injection day before sacrificed. Then, the eye balls were enucleated followed by HE staining, terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and transmission electron microscope (TEM) detection.RESULTS:The amplitude of b-wave of the treatment eyes was reached to its peak, (137.35±7.41) mV, at the 7th day post-injection and still been revealed (57.91±9.27)mV at the 17th day post-injection. But the ERG resembled flat form in the control eyes at 7th post-injection day and later. The TUNEL- positive specific cells were found at day 12 in treatment eyes and day 7 in control eyes after injection. The loss of large number of outer nuclear cells just found in the control eyes induced the whole retina become thinner than that of treatment eyes at day 17 after injection. Under the TEM, apoptosis specific karyopyknosis were observed as early as 7days after injection in the control eyes. On the contrary, those karyopyknosis could be seen till 17 days after injection in the treatment eyes. CONCLUSION: Z-LEHD-FMK could effectively defer the apoptosis of photoreceptors in RCS rats, which indicate that caspase-9 play an important role in the apoptosis of photoreceptor in RCS rats.