糖尿病大鼠视网膜病变细胞凋亡的观察

目的 探讨早、中、晚期不同病程糖尿病(DM)大鼠视网膜病变(DR)毛细血管周细胞、内皮细胞凋亡的发生，为研究DR发病机制提供形态学依据。方法 90只雄性SD大鼠随机分成正常对照组(n=30)及链脲佐菌素(STZ)糖尿病大鼠6、9、12个月模型组(n=20)。各实验组分别按期处死10只大鼠，取眼球作视网膜消化铺片，PAS染色及核苷酸末端转移酶介导dUTP缺口翻译法(TUNEL法)特异性标记凋亡细胞，光镜下观察。结果 6个月模型组，TUNEL标记法显示周细胞凋亡，但未见内皮细胞凋亡。9个月模型组，PAS染色、TUNEL标记法显示周细胞、内皮细胞均有凋亡，周细胞及内皮细胞出现核固缩、核破碎、凋亡小体形成等细胞凋亡形态学改变。12个月模型组，内皮细胞凋亡多见，部分区域每个高倍视野下可见2～3个不同时期的内皮细胞凋亡。结论 DR期间内皮细胞及细胞周细胞均可发生凋亡，DR早期以周细胞凋亡为主，中晚期内皮细胞发生凋亡，并逐渐增多。

Experimental study on programmed retinal cell death in diabetic rats

Objective To determine the occurrence of cell dea th in situ in diabetic-like retinopathy from the streptozotocin (STZ)-induced diabetic rats after 6, 9, 12 months. Methods 90 male Sprague -Dawley rats were randomly divided into normal control group (n=30) and dia betic model group. STZ were used to induce diabetes in rats. Rats in each grou p were frequently examined with blood glucose and weight, and killed after 6, 9, 12 months(n=20). The sections prepared from the trypsin-digested retina w ere studies with periodic acid-schiff-hematoxylin stain. The terminal deoxynuc leotidyl transferase-mediated dUTP nick end labeling (TUNEL) reaction was used to detect the preferentially apoptotic DNA fragmentation. Results Retinal microvessels of 6 month diabetic rats showed TUNEL-positive pericy tes, which were absent in control rats. Retinal micrographs of 9, 12 month diab etic rats showed pericytes and endothelial cell apoptosis respectively with TUNE L reaction and PAS stain. At 12 months, the numbers of apoptotic endothelial ce lls were more, and each of the pictures showed TUNRL-positive endothelial cell or apoptotic bodies under the light microscope. Conclusions These findings indicate that diabetes leads to the accelerated death in situ of pericyte in the early stages of retinopathy, and with the advance of disease th e endothelial cell apoptosis occurs.