睫状神经营养因子对大鼠急性高眼压眼视网膜神经节细胞的保护作用

Protective effect of ciliary neurotrophic factor on retinal ganglion cell in acute ocular hypertension rat

背景青光眼可以引起视网膜神经节细胞（RGCs）凋亡，据报道睫状神经营养因子（CNTF）对外伤性视神经损伤有修复作用，其是否对青光眼视神经病变有保护作用尚少见报道。目的观察CNTF对大鼠急性高眼压眼RGCs的保护作用。方法24只Wistar大鼠双眼采用眼前房平衡盐液加压灌注法建立大鼠急性高眼压模型，造模前2d左眼玻璃体内注入0．5DgCNTF5斗l，右眼以同样的方法注射磷酸钠溶液5¨l，另取3只正常大鼠作为正常对照。造模后1、3、7、14d过量麻醉法处死动物并摘除眼球，制备视网膜组织学切片后采用苏木精一伊红染色法进行形态学观察，光学显微镜下计数RGCs数目；采用免疫组织化学染色法观察RGCs层谷氨酸的表达情况。结果正常对照组大鼠视网膜各层排列整齐，细胞边界清晰；模型对照组大鼠RGCs细胞膜、细胞核均发现异常改变，有细胞空泡样变；CNTF治疗组大鼠造模后变性的RGCs数量少。与模型对照组比较，造模后3、7、14dCNTF治疗组RGCs数目明显增加，差异均有统计学意义（均P=0．000）。免疫组织化学染色表明，造模后3～7d，CNTF治疗组RGCs层谷氨酸阳性细胞数分别为（5．50±1．04）个／3个高倍视野和（6．00±1．41）个／3个高倍视野，明显低于模型对照组的（9．00＋2．91）个／3个高倍视野和（10．834-1．94）个／3个高倍视野，差异均有统计学意义（均P=0．000），而造模后1d和14d两组间谷氨酸阳性细胞数的差异均无统计学意义（P=0．578、0．180）。结论CNTF能够下调急性高眼压眼谷氨酸在RGCs中的表达。

Background Glaucoma associates with apoptosis of retinal ganglion cells （RGCs）. Research showed that ciliary neurotrophic factor （CNTF） can repair optic nerve trauma,but it has not reported whether CNTF has a protective effect on glaucomatous optic neuropathy. Objective This experimental study was to explore the protective effect of CNTF on RGCs in rat eyes with acute ocular hypertension. Methods Ocular acute hypertension models were induced in bilateral eyes of 24 clean Wistar rats by forced perfusion of a balanced salt solution into the anterior chamber. Two days before molding,0.5 μg recombinant human C NTF （5μl） was injected intravitreously in the left eyes,and 5 mmol/L sodium phosphate solution （5 μl） was injected in the same way as the control group. Three other Wistar rats were used as the normal control group. The animals were sacrificed by excessive anesthesia and the retinal sections were prepared 1,3,7,14 days after molding. The morphology of the retina was examined and RGCs counting was performed by hematoxylin ＆ eosin staining and observed under a light microscope. The expression of glutamic acid in RGCs was assessed by immunoehemistry. Results Regular retinal structure with clearly defined cell layers were observed in normal control rats. Changes in vacuoles in RGCs were seen in the model control group. The number of degenerative RGCs decreased in the CNTF group. Compared with the model control group,number of normal RGCs increased from 1 day to 14 days after molding with a significant difference between the two groups （all P=O. 000）. Immunochemistry assay showed that the numbers of positive cells for glutamie acid were 5.50±1.04 and 6.00±1.41 for the average of 3 fields at 3 days or 7 days in the CNTF group, and those in the model control group were 9.00 ± 2.91 and 10.83 ± 1.94, respectively, showing significant differences between them （ all P = 0. 000 ）. However,no comparable differences were found in the numbers of positive cells for glutamic acid at 1 day and 14 days between the two groups（P=0. 578,0. 180）. Conclusions CNTF down-regulates the expression of glutamic acid in RGCs and offers neuroprotection for RGCs in an acute glaucoma rat model.