The Study Of Neural Protection On Venom Nerve Growth Factor After Optic Nerve Crush Injury In Rat

Objective:To study the neuroprotective effects and mechanism of venom nerve growth factor on retinal ganglion cells after optic nerve crush injury in rats by observing GAP-43(growth associated protein-43),NFs(neurofilaments), MAP1B(microtubule associated protein-1B),tau protein,MBP(myelin basic protein).Methods:Forty-eight SD rats were divided into experimental and experimental control groups at random.The rat's optic nerves were crushed by using mini-vascular nip.After crushed the optic nerves of the left eyes, 100U/0.025ml of vNGF were injected into the vitreous of experimental group injury eyes and 0.025ml of balance salt solution were injected into the vitreous of experimental control group injury eyes.The right eyes were not treated with anything as normal control group.In 4 days,7 days,14 days after injury,the number of the RGCs were counted by using image analysis system,and the immunohistochemical staining of the GAP-43,NFs,MAP1B,Tau protein,MBP were observed.Result:(1)In 4-14 days after injury,the number of RGCs in the experimental group and experimental control groups were lower than normal control group by using microscope.The differences were significant(P＜0.01); the number of RGCs in experimental group were higher than that in the experimental control group.The differences were significant(P＜0.01);(2)The results of immunohistochemical staining:①GAP-43:The expression of GAP-43 in the experimental group was obvious at 4 days and enhanced gradually at 7 days,then decreased slightly at 14 days.There were also expression of GAP-43 in the experimental control groups at 4 days and 7 days but not so obvious as that in experimental group,and then decreased slightly at 14 days.The positive rates of RGCs in different durations of experimental group were higher than that in the experimental control group.The differences were significant(P＜0.01).②NFs:The expression of NFs in the experimental group increased continually at 4 days,7 days,and 14 days.There were similar expression in the experimental control groups,but not so obvious as that in experimental group.The averages of gray scale of NFs in different durations of experimental group were lower than that in the experimental control group.The differences were significant(P＜0.01).③MAP1B:The expression of MAP1B in the experimental group increased gradually,and reached the peak at 14 days;the expression of MAP1B in the experimental control group can be found at 4 days, then increased gradually and reached the peak at 7 days,and decreased at 14 days.But it's not as obvious as that in experimental group.The positive rates of RGCs in different durations of experimental group were higher than that in the experimental control group.The differences were significant(P＜0.01).④Tau: The expression of Tau in both groups increased with times,and reached the peak at 14 days.But the expression in experimental group was higher than that in the experimental control group.There were not significant differences of positive rates of RGCs between the experimental and experimental control groups at 4 days(P＞0.05).But the differences at 7 days and 14 days were significant (P＜0.01).⑤MBP:expression of MBP in both experimental group and experimental control group can be observed after injury and were gradually decreasing during 14 days.The expression of MBP in experimental group were less apparent than experimental control group and decreased obviously at 14 days,while expression of MBP in experimental control group were still obvious at 14 days.The positive rates of RGCs in different durations of experimental group were lower than that in the experimental control group.The differences were significant(P＜0.01).Conclusion:in 4-14 days after optic nerve crush injury,vNGF is effective in promoting the number of retinal ganglion cells.The study shows vNGF has neuroprotective effects on retinal ganglion cells by evoking the expression of the GAP-43,NFs,MAP1B,Tau protein while decrease the expression of the MBP.