The Improvement Of CGRP Via CAMP /PPARγ/eNOS Pathway On Vascular Endothelial Cells Insulin Resistance

Background and Objectives: Vascular dysfunction is a major complication of diabetes mellitus. The injury of endothelial cells or glucose utilization obstacle plays an important part in the remodeling of vascular function. By establishment of endothelial cell model of insulin resistance(IR), in the present study, we explore the protective effect and the mechanism of signal transduction of highly potent vasoactive peptide—the calcitonin gene related peptide(CGRP) released by sensory nerve terminal on human umbilical vein endothelial cell(HUVEC)IR model.Methods: HUVECs was cultured in vitro and was incubated with different concentrations of insulin and 33.3mmol/L high glucose,then glucose consumption and cell glycogen synthesis was examined by collecting the supernatant of cultured cells, and expression of eNOS protein; Then, the endothelial IR model was treated with 10nmol/L CGRP, and the GOP-POD method and An-throne-Sulfuric Acid methods were respectively employed to detect whether CGRP increase endothelial cells IR model of glucose consumption ability and glycogen synthesis ability. At the same time, the Western blot was used to detect the protein expression of PPARγ and eNOS, RT-PCR was used to detect the mRNA expression of PPARγ and eNOS. In order to determine whether cAMP involved in the signal transduction of CGRP in activation of PPARγ and eNOS or not, SQ22536, a specific inhibitor of the adenylate cyclase, was used to inhibite the generation of cAMP.Results: The insulin resistence( IR) model of vascular endothelial cells was successfully established when cells treated with 33.3mmol/L high glucose and 5μmol/L insulin, the vascular endothelial cells of IR model group becomes large, fuzzy boundary and abnormal shape compared to the normal group of endothelial cells; when cells induced were incubated with high glucose and high insulin in 24 h and 48 h respectively, the glucose consumption was reduced by 20% and 31%,and the glycogen synthesis was reduced by 55% and 64%(P < 0.01). The expression of PPARγ and eNOS decreased(P < 0.05). 10nmol/L CGRP significantly increased glucose consumption about 20%, and glycogen synthesis increased about 70%(P < 0.01), compared with IR group.Meanwhile, 10nmol/L CGRP increased the protein and mRNA expression of PPARγ and eNOS(P <0.05); when using SQ22536 to block cAMP downstream, the protein expression of PPARγ and eNOS was obviously reduced. At the same time, the mRNA expression of PPARγ and eNOS was also reduced compared with the IR+CGRP group (P<0.05).Conclusion: CGRP could improve the endothelial cell insulin resistence by c AMP / PPARγ and e NOS signaling pathway.