An Experimental Study Of Protection Effect Of Viper Venom Nerve Growth Factor On Experimental Retinal Ischemia/reperfusion Injury

Objective To evaluate the protection effect and mechanism of viper venom nervegrowth factor(vNGF) injected into the vitreous cavity on experimental retinalischemia/reperfusion injury (RIR).Method The Spregue-Dawley(SD) rat model of experimental retinalischemia/reperfusion injury was made by increasing the intraocular pressure. Therats were divided into normal, Balanced Salt Solution (BSS) treatment and vNGFtreatment groups randomly. At the beginning of reperfusion, 25μl of BSS wasinjected into the vitreous cavity in BSS group and 25μl (100BU) of vNGF wasinjected into the vNGF group. The histological, ultrastructural changes and theexpression of MAP1B in retina at different time after reperfusion were observed.The retinal ganglion cell number was counted and the thickness of inner layer ofretina was measured by using image diagnosis system. The ultrastructuralmorphology was examined under transmission electron microscope(TEM). Theexpression of MAP1B was studied by immunohistochemistry.Result In the early period of retinal ischemia/reperfusion injury, the edematousstatus of retina of vNGF group was lighter than that of the BSS group. Thethickness of retinal inner layer declined gradually since 2 hours after reperfusionand the RGC numbers decreased gradually since 6 hours after reperfusion in BSSgroup. In contrast, The RGC numbers did not decrease more since 24 hours afterreperfusion and the thickness of retinal inner layer increased gradually since 48hours after reperfusion in vNGF group. At 168 hours after reperfusion, thethickness of the retinal inner layer and the RGC numbers of BSS groups wereobviously lower than that of the normal groups and vNGF group, the differences ofstatistical were very importance(P<0.01). At 24 hours after reperfusion of BSSgroup, the arrangement of the membrane disc became disordered and distorted.Most chondriosomes of nerve fiber layer were swelling and vacuolating, thechromatin of RGCs was concentrated and marginate, the apoptotic body can befound. organelles in the cytoplasm were swelling, vacuolating and decreasing.While in the vNGF group, the arrangement of the membrane disc were tidy, theswell of RGCs was more slight, more abundant organelles in the cytoplast than inthe BSS group, chondriosomes of nerve fiber layer were swelling slightly,and thestructure of microtubule was clear. The changes of retinal ultrastructuralmorphology in the vNGF group were better than in the BSS group in the rat. Theexpression of MAP1B was found in normal group. In BSS group, the expression ofMAP1B enhanced gradually at 24h after reperfusion, reached the peak at 96h,decreased at 120h, and then the expression of MAP1B at 168h was similar asnormal group. In vNGF group, the expression of MAP1B enhanced gradually at 6hafter reperfusion, reached the peak at 48h at when the concentration of stain wasstronger than that at 96h in BSS group.Conclusion Injection of vNGF into the vitreous cavity has the protection effecton experimental retinal ischemia/reperfusion injury through reducing the injury ofthe retinal inner layer and enhancing the expression of MAP1B to promote theregeneration of retinal nerve fiber.