The Role And Mechanism Of Alpha 1nicotinic Receptor In Atherosclerosis Induced By Nicotine

Backgrounds: Nicotine is an important substance in tobacco in promoting atherosclerosis.The molecular mechanism of nicotine in atherogenesis is not clear and is the research focus.Alpha1 nicotinic receptor(nAChRα1)is one of the important receptor to nicotine,which is widely distributed in vascular smooth muscle cells,macrophages and endothelial cells.The role of nAChRα1 in nicotine-mediated atherosclerosis has not been reported both home and abroad.nicotine increases nAChRα1 expression in the tracheal endothelial cells,and the increment of nAChRα1will activate Calpain-1,which modulates the MMPs activity of vascular smooth muscle cells.Both Calpain-1and MMPs are important proteases in promotion of atherosclerosis.Our previous study showed that nicotine can increase MMPs expression in both smooth muscle cells and macrophages.Objective: On the basis of pur previous study,the purpose of this study was to elucidate the role of n ACh Rα in atherosclerosis induced by nicotine.We also to further research wheather n ACh Rα impacts the proliferation and migration of aortic vascular smooth muscle cells(MAVOS)and macrophages(RAW264.7),and the mechanism underlying.Moreover,to study the expression of MMP-2and MMP-9 in nicotine stimulates the two cells via nAChRα1.Methods: In vivo experiment,mices were injected by nicotine(2mg/kg/d)and administered with a high-fat diet,meanwhile treat adenoassociated virus(AAV)to Silencing n ACh Rα.Oil red O stain was used to measure lesion areas in aortic.Western Blot and Real-Time PCR were used to assess the expression of Calpain-1,MMP-2and MMP-9 in the mouse aortic tissue.ELISA was used to the level of IL-6,IL-10,TNF-α in the mouse serum.In Vitro,nicotine(0.5ng/ml)and si RNA which could reduce the expression of nAChRα1 were used to pretreat MOVAS cells and RAW264.7 cells,the level of Calpain-1,MMP-2 and MMP-9in cells was assess by Western Blot and Rea-Time PCR.wound were used to observe the migration of two cells.CCK-8 assay was used to evaluate the proliferation of cells.Results: nAChRα1 play an important role in the nicotine induced atherosclerosis,what is more it also impact the releases of inflammation factor and the level of lipid in serum.Inhibition of n ACh R α can suppress the nicotine stimulated migration of MOVAS cells and RAW.cells by downregulating the expression of Calpain-1,MMP-2 and MMP-9.Migration from tunica media to intima and foam cells are increased by nicotine exposed via n ACh Rα.Conclusion: The effect of nicotine on atherogenesis due to nAChRα1 mediated activation of Calpain-1/MMP-2/MMP-9 signalling pathway on MOVAS cells and RAW264.7cells,inducing the migration and proliferation of vascular smooth muscle cell and macrophage,and inflammatory reaction.