Abstract:Aim To investigate whether ischemia-induced neovascularization is impaired in diabetic mice and the effect of insulin administration on this dysfunction and the underling mechanisms. Methods Unilateral hindlimb ischemia was performed in streptozotocin-induced diabetic mice(C57BL/6) by left femoral artery ligation.The plasma vascular endothelial growth factor(VEGF) and stromal-derived growth factor 1α(SDF-1α) levels were measured by ELISA before ligation and 1,3,7,14 days after ischemia.Capillary density was determined in both ischemic and non-ischemic gastrocnemius muscles by CD31 staining.The local expressions of VEGF,endothelial nitric oxide synthase(eNOS),phospho-eNOS,protein kinase B(PKB,Akt) and phospho-Akt were quantified by Western blotting. Results After ischemia,diabetic mice showed abrogated capillary density increase in the ischemic tissue compared with non-diabetic mice(day7: 7.65±1.74 vs 18.22±3.77,P><0.05),which were accompanied by impeded release of plasma VEGF and SDF-1α(P><0.01),and impaired upregulation of local VEGF protein expression as well as Akt and eNOS phosphorylation(P><0.05).Insulin administration significantly ameliorated ischemia-induced angiogenesis in treated compared with non-treated diabetic groups(15.36 ± 2.14 vs 7.65 ±1.74,P><0.05),elevated plasma levels of VEGF and SDF-1α(P><0.01),as well as enhanced local VEGF expression and Akt/eNOS phosphorylation(P><0.05). Conclusion The data suggested that insulin administration efficiently improved impaired ischemia-induced neovascularization in diabetic mice which may be attributed to restoration of attenuated SDF-1α/VEGF/Akt/eNOS activation.