| Objective:Diabetic cardiomyopathy(DCM),a serious complication of diabetes mellitus,is associated with changes in myocardial structure and function.This study sought to explore the ability of insulin-like growth factor-1(IGF-1)to modulate DCM and its related mechanisms.Methods:Twenty-four male Wistar rats(weight:200-250g)purchased from Yanbian University were randomly divided into 3 groups:control group(Con group),diabetic cardiomyopathy group(DCM group)and IGF-1 treatment group(DCM+IGF-1 group).Rats in DCM group and DCM+IGF-1 group were injected singlely with streptozotocin(STZ,60 mg/kg)to mimic diabetes mellitus.After 72 hours of STZ injection,fasting blood glucose(FBG)was measured.When the,the diabetes models were considered to be successful as their FBG?16.7mmol/L.IGF-1 group rats were treated with IGF-1 for ten weeks.At the end of treatment,all rats'body weight and fasting blood glucose were tested,meanwhile,their blood,urine and myocardium were collected.Serum triglycerides and total cholesterol were detected.And the levels of inflammatory factors(IL-1? and TNF-?)and oxidative stress markers(MDA and SOD)were examined.In addition,the structural changes and organelle morphology of myocardium were observed by related staining.The expression of Bcl-2/Bax in cardiomyocytes was detected by Western blot.TUNEL staining was used to estimate the cardiomyocyte apoptosis.Finally,the myocardium was detected by Western blot,and the expression of Akt,GSK-3? and their phosphorylation were observed.Results:1.Basic situation performace.The rats in the DCM group showed polydipsia,polyphagia,polyuria(significant increase in urine output,P<0.05),and their weight were significantly higher than those in the Con group(P<0.05);burnout,less activity;fur yellowing,dull;milky white pupil were obsevered in DCM rats.The body weight of DCM rats increased significantly(P<0.05)becaused of the reduced uiine volume(P<0.05)induced by IGF-1 administration,but the eyes' color failure to improve.2.Serum IL-1? and TNF-? of diabetic rats were significantly increased(P<0.05),that prove inflammation occurres.After treatment with IGF-1,the levels of IL-1? and TNF-? in serum were significantly decreased(P<0.05)and close to normal levels.IGF-1 had a resistance to diabetes-induced inflammatory response.3.The activity of SOD was significantly decreased(P<0.05),while the content of MDA was significantly increased(P<0.05),indicating that oxidative stress was obvious in rats with DCM.When IGF-1,SOD activity increased(P<0.05),MDA content decreased(P<0.05)of rats in IGF-1 treatment group.4.Morphological observation of myocardial cells:HE staining results show normal myocardial tissue structure,myocardial fibers arranged neatly,homogeneous cytoplasm,the nucleus size uniform,round or oval,located in the central cell;and DCM group show visible and irregular myocardial fiber disorder;in DM + IGF group,myocardial structure was significantly improved.Masson staining showed that the fibers in the DCM group were stained blue and were distributed in the blood vessels.The degree of myocardial interstitial fibrosis was significantly reduced,the area was significantly reduced(P<0.05).The ultrastructure of the myocardium in the normal group was normal.The mitochondrial damage was obvious in the DCM group:mitochondrial swelling,vacuolization,rupture and disappearance of the mitochondria.After IGF-1 treatment,the ultrastructural damage of the myocardium improved.5.The levels of IL-1? and TNF-? in serum were 12.73 ± 0.79 ng/L and 152.6 ±12.04 ng/L,respectively in Con group.In the DCM group,the levels of IL-1? and TNF-? in serum were significantly increased by 17.47±1.49 ng/L and 281.90 ±14.04 ng/L(P<0.05).The levels of IL-1? and TNF-?:16.13 ± 0.82 ng/L,220.10±11.95.ng/L(P<0.05).Indicating that IGF-1 may protect against diabetic cardiomyopathy by resisting inflammatory responses.6.Changes in oxidative stress markers:Under normal circumstances,high SOD activity and low MDA content can not cause oxidative stress;when the occurrence of diabetic cardiomyopathy,SOD activity was significantly reduced(P<0.05),and the level of serum MDA was increased(P<0.05).The activity of SOD in IGF-1 group was significantly higher than that in DCM group(P<0.05),and the MDA countence was significantly lower than that in DCM group(P<0.05),which indicated that IGF-1 could protect the occurrence and development of diabetic cardiomyopathy by inhibiting oxidative stress.7.Apoptosis was observed by TUNEL staining.The apoptosis of cardiomyocytes in the normal group was limited.The apoptosis of cardiomyocytes was induced by DCM significantly(P<0.05).Apoptotic cells' number in DCM+IGF-1 group was significantly lower than that in DCM group(P<0.05).In addition,the ratio Bcl-2/Bax ratio was consistent with the trend of TUNEL fluorescence intensity change.8.The expression of Akt,GSK-3? and its phosphorylation in cardiomyocytes of DCM rats were significantly higher than those in normal rats(P<0.05).Compared with DCM group,the ratio of p-Akt/Akt and p-GSK3?/GSK3? protein of rats' hearts in DCM+IGF-1 group were significantly increased(P<0.05).Conclusion:IGF-1 ameliorates the DCM through anti-inflammation,anti-oxidative stress along with activation of the Akt/GSK-3? signaling pathway. |
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