Effect Of Mouse Nerve Growth Factor To Aquaporin-2 Expression In Rat Dorsal Root Ganglion After Chronic Constriction Injury

Background and Objective:Mouse nerve growth factor(mNGF)is a kind of biologically active that is extracted from the submandibular gland of the mouse,Its relative molecular mass is 26.5×103,it has the nutritional effect on the normal cells of human nervous system and can promote damaged nerve to recovery.mNGF Has been already widely used in the treatment of central nervous system injury and achieved good clinical results.The dorsal root ganglion is a sensory neuronal cell accumulation area,damage can lead to the body sensory sensory dysfunction.It is very common in clinical practice that lumbar degeneration leads to dorsal root ganglion injury,therefore,the repair of dorsal root ganglion is of great significance to clinical work.In this study,we tied up the sciatic nerve to establish the model of dorsal root ganglion injury,and study the role of mNGF in promoting nerve recovery after chronic constriction injury,observe the effect on aquaporin-2 expression in the dorsal root ganglion,and finally provide a theoretical basis for clinical treatment.Methods:90 male Sprague-Dawley rats were used,Weighted 200-250 g,all the rats were randomly divided into three groups: sham operation group,operation group,mNGF treatment group,30 rats in each group,The left sciatic nerve was exposed in the sham operation group.the left sciatic nerve was exposed proximal to its trifurcation,four ligatures were then loosely tied around the nerve at 1–2 mm distance using 4–0 chromic gut suture materia,the length of the nerve ligation is about 4.5 mm,and then sutured layer by layer.MNGF group were treated with the same operation.All the three groups were tested with Plantar(Hargreaves)test and Von Frey test of mechanical threshold 0 day before surgery,3 days,7 days and 14 days after surgery.At the time of 3 days,7 days,and 14 days after surgery.Immunohistochemical staining and Western blot analysis of dorsal root ganglion specimens were performed and quantitative analysis of AQP-2 expression changes Results: 1 Behavioural teststhe three groups of the paw withdrawaI latency time at the 3rd day were 13.5±0.6s,5.4±0.3s,6.4±0.4s respectively,at the 7th day were 13.5±0.6s,5.8±0.3s,8.3±0.7s respectively,and at the 14 th day were 13.3±0.6s,5.8±0.3s,10.7±0.8s,There were significant differences among the three groups at the 3rd day,7th day and 14 th day after surgery(P <0.05);The three groups of the thresholds of mechanical compression at the 3rd day were 34.3±1.3s,15.9±0.8s,22.5±0.8s respectively,at the 7th day were 34.3±0.9s,15.9±1.0s,24.8±0.8s respectively,and at the 14 th day were 34.3±0.5s,15.6±0.6s,28.6±1.3s,There were significant differences among the three groups at the 3rd day,7th day and 14 th day after surgery(P <0.05)2 Immunohistochemical stainingThe sham operation group was lightly stained on the 3rd,7th and 14 th day after surgery,and the dyeing of the DRG was not changed with the time.Immunohistochemical staining was performed on the third day after operation.A large number of spotted DRG cells were stained with brownish yellow,he staining of positive cells was not changed on the 7th day and the 14 th day.there was not much difference between mNGF treatment group and operation group of the degree of staining in the third day and 7th day,On the 14 th day,the number of stained cells was significantly reduced and the staining was lighter.3 Western blot analysisThe expression of Aquaporin-2 in the dorsal root ganglion of the sham operation group,the operation group and the mNGF group was quantitatively analyzed at the 3rd,7th and 14 th day after surgery,The results are expressed as the mean ± standard deviation of the integrated optical density(IOD)value.The IOD were 328±20,2744± 77,2173±110 of the operation group,sham operation group and mNGF group respectively at the 3rd day.There was significant differences among the three groups(P <0.05).The IOD were 323±16,2299±93,1664±54 of the operation group,sham operation group and mNGF group respectively at the 7th day.There was significant differences among the three groups(P <0.05).The IOD were 323±16,1948±40,841±46 of the operation group,sham operation group and mNGF group respectively at the 14 th day.There was significant differences among the three groups(P <0.05).Conclusion:The treatment of mNGF to dorsal root ganglion after Chronic constriction injury can significantly increase the paw withdrawaI latency and improve the threshold of mechanical stimulation,The expression of AQP-2 in dorsal root ganglion can be increased after chronic constriction injury,mNGF can reduce the expression of AQP-2.