| Objectives: 1.A diabetic rat model of macroangiopathy was established to observe the expression of autophagy-related proteins in thoracic aorta tissues.2.Sitagliptin was intervened in the model of diabetic rats which had macrovascular complications to observe the changes of autophagy activity in thoracic aorta tissue and explore the possible mechanism.Methods: Fifty-eight SD rats aged 5 weeks old(weigh about 180g-200g)were randomly selected and adaptively fed for 1 week.They were randomly divided into normal control group(group A,n=10)and model group(n=48).Group A was fed with normal food,and the model group was fed with high-fat and high-carbohydrate food.After 4 weeks,BW was measured and FBG,FINS,TG,TC and LDL-C levels were tested in these rats.After the model group was fasted for 12 hours,35 mg/kg dose of STZ was intraperitoneally administered,and the group A received equivalent buffer by intraperitoneal injection.Diabetic rats were identified as whose random blood glucose(BS)was more than 16.7 mmol/L by testing 3 consecutive times after 72 hours(3 rats were not successfully modeled).The successful model of the rats continued to be fed with a high fat diet and then randomly divided into 5 groups: Group B: un-pretreated group(n=9),Group C: Sitagliptin with 5 mg/kg·d dose group(n= 9),Group D: Sitagliptin with 1 mg/kg·d dose group(n=9),E group: Sitagliptin with 5 mg/kg·d dose+ CXCR4 specific inhibitor AMD3100 with 1 mg/kg·d dose group(n= 9),Group F: Sitagliptin with 1 mg/kg·d+ CXCR4 specific inhibitor AMD3100 dose 1 mg/kg·d group(n=9).Group C,D,E,and F groups were treated with sitagliptin dissolved in normal saline at 9 o'clock per day,gavage was performed in groups A and B with equal volume of normal saline for 8 weeks.In groups E and F,AMD 3100 1 mg/kg·d was intraperitoneally injected daily from the 8th week of the experiment.During the dosing period,one mouse died in groups B,C,and F.At the end of the twelfth week of the experiment,the rats were sacrificed after body weight and blood was taken from the apex of the heart at 3-4 ml to detect blood biochemical markers and serum stromal cell-derived factor-1(SDF-1?)levels.The thoracic aorta segment of rats was partially stained with HE,part of it was used for immunohistochemical staining,and a portion was used for Western-blot detection for LC3-II,P62,Beclin-1,Class III PI3 K,and CXCR4 protein expression.Results: 1?At the end of the 4th week,BW and biochemical indexes of each rat were compared.Compared with group A,BW,FBG,FINS,HOMA-IR,TG,TC,and LDL-C in the model group were significantly higher.2?At the end of the 12 th week,the rat FBG,TC,TG,and LDL-C indexes were compared in each group rats: Compared with group A,the levels of FBG,TC,TG,and LDL-C in group B,C,D,E,F increased.Compared with group B and D,the levels of FBG,TC,TG,and LDL-C in group C decreased.Compared with group F,the levels of FBG,TC,TG,and LDL-C in group E decreased and the difference has statistical significance(P<0.05).3?The levels of serum SDF-1?,CXCR4,and autophagy-related protein expression in thoracic aorta tissue were compared at the end of 12 th week: Compared with group B,serum SDF-1?,LC3-II,CXCR4,Beclin-1,and Class III PI3 K protein expression increased,P62 expression decreased,the difference was statistically significant(P <0.05).while compared with group D,SDF-1?,LC3-II,CXCR4,Beclin-1,and Class III PI3 K protein expression in group C increased significantly,and the expression of P62 reduced obviously.The difference was statistically significant(P<0.05).when Comparing group C with group E and group D with group F,the expression of SDF-1?,LC3-II,CXCR4,Beclin-1 and Class III PI3 K protein in serum increased and P62 expression decreased.There was no significant difference between group E and group F.Conclusions: 1.The expression of LC3-II,Beclin-1 and Class III PI3 K in the aorta tissue of STZ-induced diabetic rats was down-regulated,the expression of P62 protein was up-regulated and the autophagic activity decreased.2.Sitagliptin may regulate autophagy by activating SDF-1?/CXCR4 biological axis,which may further delay the macrovascular lesions in diabetic rats. |
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