兔视神经损伤后视网膜一氧化氮的表达与神经节细胞凋亡关系的研究

目的通过建立兔视神经夹伤模型，观察伤后视网膜组织中一氧化氮的表达与视网膜神经节细胞（RGCs）凋亡的关系，从而探讨RGCs凋亡机制及氨基胍（AG）在伤后对RGCs的保护性作用。方法55只成年大耳白兔，随机分正常对照组（5只）、损伤对照组（25只）、AG治疗组（25只）。损伤组双眼夹伤视神经，按伤后1、3、7、14、21d又随机分为5组（5只／组）。AG治疗组于伤后2min耳缘静脉注射2％AG，损伤对照组同法注射生理盐水。应用TUNEL染色计数凋亡阳性细胞；比色法测量一氧化氮（NO）含量、诱导型一氧化氮合酶（iNOS）活力。结果正常组视网膜切片中极少见RGCs凋亡。损伤组于伤后1d偶见，3—7d逐渐增多，至14d达高峰，之后逐渐下降。正常视网膜组织中很少表达iNOS，但含有少量NO。在损伤后二者含量逐渐增高，与RGCs凋亡呈正相关性。同一时间点损伤对照组和AG治疗组比较差异有统计学意义。结论兔视神经夹伤后，NO合成增多可能是引起RGCs凋亡的一个因素。而AG通过减少NO的合成，降低RGCs凋亡，对RGCs有保护性作用。

A research about the correlation between expression of nitric oxide at retina and the apoptosis of retinal ganglion cells after optic nerve injury in rabbits

Objective Through establishing the model of optic nerve crush in rabbits, to observe expression of nitric oxide （NO） in retinal tissue and apoptosis of retinal ganglion cells after trauma, to investigate the apoptosis mechanism of RGCs and protective effect of Aminoguanidine （AG） to RGCs after injury. Methods Fifty - five adult rabbits were randomly divided into normal control group （ n = 5 ） , injury control group （n = 25 ） and AG treatment group （ n = 25 ）. The optic nerve of both eyes were crushed in injury group, According to 1 d,3 d,7 d,14 d and 21 d after injury,the injury group were divided into 5 subgroups （n = 5 ）. AG treatment group were injected 2% AG through ear-border vein 2 rain after injury. The injury control group were injected equal volume of NS through ear-border vein. Retinal slice stained TUNEL was selected to locate and calculate apoptosis cells. NO content and inducible nitric oxide synthase （iNOS） vitality were determined with biochemistry method. Results Few apoptosis cells were detected at normal retina. A few apoptosis cells were detected in ld after injury, there were a significant number of TUNEL positive cells in 3 -7d after injury, The number of TUNEL positive cells reached a maximum in 14 d after injury, followed by a decrease, iNOS was expressed rarely in normal retinal tissue, but it contains a small amount of NO. Both content increased gradually after injury, the expression of NO and iNOS were positive correlated with apoptosis of RGCs. The injury in treatment group and the injury in control group were significantly different （ P 〈 0.05 ） at the same time point. Conclusion The experiment show that the increase of NO synthesis may be a factor apoptosis of RGCs after optic nerve crush in rabbits. AG can reduce NO synthesis, reduce the degree of apoptosis of RGCs, and protect the RGCs after optic nerve injury.