大鼠慢性高眼压诱导视神经损伤的研究

Optic nerve damage induced by chronic intraocular hypertension in rats

目的建立大鼠慢性高眼压模型,对其眼压、视网膜节细胞(RGCs)和视神经轴突损伤进行研究。方法对40只大鼠行慢性高眼压模型手术,分为4组:术后即刻、5 d、2周和4周,每组10只,分别测定眼压。采用全视网膜-RGCs Cresyl Violet染色,术后2周和4周对大鼠视网膜进行RGCs计数,并对视神经进行对位苯二胺(PPD)染色。对照组20只大鼠,分为2组,每组10只。结果31只大鼠眼压升高,眼压升高率为77.5%,且4周内眼压维持稳定。眼压升高2周时中心和周边RGCs分别减少11.0%和11.3%,眼压升高4周时中心和周边视网膜分别丢失RGCs达17%和24.6%,与正常对照组比较差异均有统计学意义(P<0.05);而眼压未升高的RGCs未见明显丢失,与正常对照组相比差异无统计学意义(P>0.05)。高眼压组大鼠视神经轴突在颞上方有大约5.3%损伤,球后1 mm的视神经在光镜下可以看到视神经轴突水肿和髓鞘碎屑。结论慢性高眼压动物模型是一种可以重复且有效的青光眼模型,它模拟了人类慢性眼压升高所导致的RGCs丢失和视神经的损伤。

Objective To establish the rat chronic intraocular hypertension model, and investigate its intraocular pressure （IOP）, retinal ganglion cells （RGCs） and optic nerve damage. Methods The operations for the establishement of chronic intraocular hypertension model were performed in 40 rats, and IOP was measured immediately, 5 days, 2 weeks and 4 weeks after surgery （n = 10 for each time point）. Cresyl Violet staining of whole-mounted retinas was used to label RGCs 2 weeks and 4 weeks after operation, and RGCs were counted. Paraphenylene diamine （PPD） staining was performed in the semi-thin cross sections of optic nerve. Another 20 rats were served as controls. Results Thirty-one rats （ 77.5% , 31/40） experienced higher IOP and maintained stable IOP in 4 weeks. The RGCs loss of 11.0% and 11.3% was found in the central and peripheral retina, respectively, after 2 weeks of IOP increase, significantly different from the RGCs of the controls（P 〈0.05）. After 4 weeks of IOP increase, the loss of RGCs was 17% for the central retina and 24.6% for the peripheral retina, significantly different from the RGCs of the controls（ P 〈 0.05）. In the retina of those with normal IOP, there was no loss of RGCs, and no significant difference was found when compared with the RGCs of the controls（P 〉 0.05）. About 5.3% damaged of optic nerve were located in the superior temporal region in those with higer IOP. There were damaged axons with axonal swelling and myelin debris in the region of affected optic nerve 1 mm posterior to the globe under light microscope. Conclusion The chronic intraocular hypertension animal model is a reproducible and effective glaucoma model, which simulates RGCs loss and damage of optic nerve induced by chronic elevation of IOP.