The Research Of The Molecular Mechanism Of Rapamycin Resistance In Diabetic Atherosclerosis

Purpose：This study use ApoE gene defects (ApoE-/-) mice as the foundation tobuild animal model of diabetic atherosclerosis, compared to this model and thesimple model of atherosclerosis in blood fat, blood sugar, atheromatous plaquearea, the component of the plaque, protein expression in plaque, the differencesof protein expression in aortic smooth muscle, so as to reveal the possiblemolecular mechanisms of rapamycin resistance.Background:The morbidity and mortality of Diabetic atherosclerosis is increasing,although rapamycin drug-eluting stents can effectively reduce the restenosisafter stent implantation, but the rate of restenosis in diabetic population afterthe use of rapamycin drug-eluting is higher than people without diabetes, itsuggests that diabetes may have rapamycin resistance.Methods:1, Build and evaluate several different diabetic atherosclerosis model inmice.46male SPF8weeks APOE-deficient mice were randomly grouped intocontrol group, high-fat group and STZ low dose group, STZ high-dose group.Control group were fed chow, high-fat group were fed with high fat feedstuff,STZ intraperitoneal injection of low dose group was given STZ55mg/kg(continuous injection of5days), STZ high dose group was given intraperitonealinjection of STZ200mg/kg (single injection). After two months, fasting bloodglucose, blood lipids and plaques area of the aortic root were assessed. EvaluateThis research was supported by two NSFC (NO.81100232/NO.81100081) the advantages and disadvantages of various methods.2, The effection of diabetes to the expression of mTOR and its downstreamtarget molecule in atheromatous plaque and artery vascular smooth muscle indiabetes mice.168-weeks male APOE-deficient mice were randomly dividedinto experimental group and control group. After adaptive feeding1week, theintraperitoneal injection of STZ55mg/kg were given to the diabetic group(continuous injection of5days), control group were given the equivalentvolume of citric acid buffer solution, then monitor blood glucose, fastingglucose>13mmol/L defined as a diabetes.2months later, body weight, fastingblood glucose, blood lipid, plaques in the aortic root were measured, theexpression of α-actin and mTOR in plague were measured byimmunohistochemical method, the expression of mTOR, p-mTOR, p-4EBP1,p-S6K1in aortic smooth musclewere methered by western-blot method.Results:1.STZ high-dose group appear high mortality; STZ low dose group expresshigher fasting blood glucose, blood lipids, and the aortic root plaque area werehigher than control group or high-fat group (P <0.01); High-fat groupmoderately elevated fasting glucose (7.78+/-0.67tendency/L).2. The diabetes express higher fasting blood glucose, blood lipid (P <0.01),the aortic root plaque area is significantly increased (P <0.01), the content ofplaque in the smooth muscle cells is increased (P <0.01). Diabetes decreasedthe expression of mTOR in plague. Diabetes decreased the expression ofmTOR,p-mTOR,p-4EBP1,p-S6K1in aortic smooth muscle (p <0.01).Conclusions:1, Small dose of multiple intraperitoneal injection of STZ is the idealmethod of preparation of diabetic atherosclerosis model; Pure high-fat feedingAPOE gene-deficient mice can lead to elevated fasting glucose; High dose of asingle injection of STZ should not be used for the preparation of diabetic animalmodels of atherosclerosis. 2, Diabetes inhibit mTOR signaling pathway and its downstream target4EBP1,S6K1, which may be one of the molecular mechanisms of rapamycinresistance in diabetes.