BACKGROUND: Effect of nerve growth factor(NGF)on angiogenesis of regenerative perpheral nerve is still researched up to now.OBJECTIVE:To evaluate the dose-response relationship and mechanism of NGF on angiogenesis of regenerative sciatic nerve in rats.DESIGN:Randomized controlled animal study.SEFFING:Department of Neurology,the 324 Hospital of Chinese PLA;the Third Laboratory,Institute of Battle Surgery,Daping Hospital of the Third Military Medical University of Chinese PLA.MATERIALS:A total of 32 healthy adult Wistar rats weighing 200-250 g and of both genders were selected in this study.Silica gel conduit was provided by Shanghai Xinya Medical Rubber-goods Factory and NGF was provided by Sigma Company,USA.METHODS:The experiment was carried out in the Third Laboratory,Institute of Battle Surgery,Daping Hospital Affiliated to the Third Military Medical University of Chinese PLA from August 2003 to February 2005.Experimental grouping:All rats were randomly divided into 4 groups,including saline group,50,100 and 500 ng NGF groups with 8 rats in each group.Experimental intervention:Sciatic nerves were cut to establish defect of 10 mm in length,and then the defect was bridged with silica gel conduit in the left latter limb.After the bridging,rats in the saline group were perfused with 5 μL saline,and rats in the NGF groups were perfused with 2.5,5 and 25μL NGF(20 mg/L),respectively.Experimental evaluation:On the 30th day,immunohistochemical technique was used to detect the expressions of CD34,vWf,vascular endothelial growth factor(VEGF)and trkA in newborn vascular endothelial cells of regenerative sciatic nerve;meanwhile,their forms were performed with quantitative analysis.MAIN OUTCOME MEASURES:Pathological and immunohistochemical changes of nerve regeneration of rats in each group.RESULTS:All 32 rats were involved in the final analysis,①Results of pathological sections of nerve regeneration in rats:Distal end of sciatic nerve was completely bridged at 30 days after operation and thickness of sciatic nerve in silica gel conduit lined in 500 ng NGF group＞50 and 100 ng NGF group＞saline group.Numbers of fiber and regularity of arrangement of sciatic nerve were superior in NGF groups to those in saline group,In addition,angiogenesis was obviously observed at 30 days after operation.②Results of immunohistochemical staining:There were significant differences among three NGF groups as compared with saline group in the expressions of four antigens (P＜0.05).Expressions of four antigens were increased in 500 ng NGF group as compared with those in 100 and 50 ng NGF groups(CD34:94.2±6.4,74.2±10.9,77.0±11,0;vWf:116.2±20.0,72.0±13.1,68.0±9.7;TrkA:105.4±10.6,57.8±11.5,58.8±6.5;VEGF:89.0±3.0,48 6±7.4,35.2±2.9;P＜0.05 or P＜0.01).CONCLUSION: NGF can promote angiogenesis of the regenerative peripheral nerves and show a dose-response relationship,while its mechanism may be related to promoting expressions of TrkA and VEGF.