鼠尾草酸对急性高眼压模型大鼠视网膜神经节细胞的保护作用

Protective effects of carnosic acid on retinal ganglion cells in acute ocular hypertension rats model

目的观察鼠尾草酸对急性高眼压模型大鼠视网膜神经节细胞（RGCs）的保护作用。方法采用抽签法将60只雄性8～12周龄SPF级SD大鼠随机分为正常对照组、鼠尾草酸组和模型对照组，每组20只。正常对照组大鼠不接受任何处理；鼠尾草酸组和模型对照组大鼠左眼采用前房内生理盐水灌注法将眼压升至110mmHg（1mmHg=0．133kPa）60min制备急性高眼压模型；鼠尾草酸组大鼠于造模后腹腔内注射鼠尾草酸（溶于DMSO）25rag／（kg·d）连续7d，模型对照组大鼠以同样的方法注射DMSO。造模后2周各组任意取10只大鼠实验眼制备视网膜切片行苏木精一伊红染色及TUNEL染色，观察大鼠视网膜形态学变化及RGCs凋亡情况，另取10只大鼠制备视网膜铺片行RGCs免疫荧光染色，计算大鼠存活的RGCs数目。结果苏木精一伊红染色显示，正常对照组大鼠视网膜结构清晰，RGCs数目多且排列紧密，细胞核边界清晰。模型对照组大鼠视网膜高度水肿，RGCs排列疏松，细胞核肿胀。鼠尾草酸组大鼠视网膜结构较为清晰，RGCs排列较模型对照组整齐。正常对照组、模型对照组和鼠尾草酸组大鼠视网膜神经纤维层（RNFL）厚度分别为（32．96±1．63）、（58．96±1．57）和（50．11±2．37）μm；各组大鼠RGCs细胞凋亡数分别为（6．92±2．96）、（29．85±6．40）和（14．69±2．98）个／视野；各组大鼠存活的RGCs数分别为（2363．17±148．45）、（1308．67±106．02）和（1614．17±96．39）个／0．235mm^2，组间总体比较差异均有统计学意义（F=339．284、81．583、122．68，均P〈0．01）。与正常对照组比较，模型对照组RNFL明显变薄，RGCs凋亡数明显增加，存活的RGCs数目明显减少；与模型对照组大鼠比较，鼠尾草酸组大鼠RNFL厚度值明显下降，RGCs凋亡数明显较少，存活的RGCs数目明显增加，差异均有统计学意义（均P〈0．01）。结论一定剂量的鼠尾草酸能明显减少急性高眼压导致的大鼠RGCs凋亡，对RGCs具有保护作用。

Objective To observe the protective effects of carnosic acid on retinal ganglion cells （RGCs） in acute ocular hypertension rats model. Methods Sixty male SPF SD rats （8-12 weeks） were randomly assigned to normal control group, carnosic-acid treated group and model control group with 20 rats for each group. The acute ocular hypertension animal model was induced by the perfusion of normal saline solution into anterior chamber of eyes to elevate the intraoeular pressure （IOP） to 110 mmHg for 60 minutes in the rats of the carnosic-acid treated group and model control group, and then the carnosic-aeid （dissolving in DMSO ） was intraperitoneally injected for consecutive 7 days in the earnosic-aeid treated group, and only DMSO was injected in the same way in the model control group. The rates were sacrificed 2 weeks after experiment and retinal sections were prepared for histopathological and apoptotic retinal ganglion cells （RGCs） examination by hemotoxylin ＆ eosin staining and TUNEL staining,and immunofluorescence was employed to examine the survival cell number of RGCs. This study protocol was approved by the Ethic Committee for Experimental Animal of Three Gorges University. Results The retinal morphology and structure were clear in the normal control group. The edema of retinal tissue, loosely arranged RGCs and swollen nucleus were seen in the model control group. In the carnosic-acid treated group, the retinal morphology and structure were regular. The retinal nerve fiber layer （RNFL） thickness was （32.96±1.63）, （58.96± 1.57） and （50.11±2.37）μm,and the apoptotic cell number was （6.92±2.96）,（29.85±6.40） and （14.69± 2.98）/field,and the survived cell number was （2 363.17±148.45） , （1 308.67±106.02） and （1 614. 17±96.39）/ 0. 235 mm^2 in the normal control group, model control group and carnosic-acid treated group, respectively, with significant differences among the groups （ F = 339. 284,81. 583,122.68, all at P〈0.01 ）. Compared with the normal control group,the RNFL thickness was thickened,the number of apoptotic RGCs was much more and the number of survived RGCs was decreased in the model control group, with significant differences （all at P〈 0. 01 ）. In the carnosic-acid treated group, the RNFL thickness was thinner, the number of apoptotic RGCs was reduced and the number of survived RGCs was increased in comparison with the normal control group,with significant differences （all at P〈0. 01 ）. Conclusions Carnosic-acid plays a protective effect on RGCs by inhibiting the cell apoptosis in acute ocular hypertension rats.