Changes of heart function and serum cardiac troponin I in early type 2 diabetic rats

AIM: To observe the changes of heart function and the expression of serum cardiac troponin I(cTnI) in early type 2 diabetic rats, and to explore the role of cTnI in the development of type 2 diabetes and early diabetic cardiomyopathy.METHODS: The type 2 diabetes rat model was established by an injection of streptozotocin after high fat diet(5 weeks). The rats were randomly divided into control group, model group of 2 weeks, and model group of 4 weeks. M-mode echocardiography was performed for echocardiographic measurements. Fasting blood glucose(FBG), total cholesterol(TC), triglyceride(TG), high density lipoprotein-cholesterol(HDL-C), low density lipoprotein- cholesterol(LDL-C), fasting insulin(FINS) and cTnI levels were tested. HE staining was used to observe the pathological changes of myocardial structures. The alteration of cTnI in myocardium was determined by Western blot.RESULTS: Compared with normal group, the levels of TC, TG and LDL-C in type 2 diabetic rats were significantly increased, HDL-C levels were significantly reduced. Cardiac histological analysis revealed that type 2 diabetes induced cardiomyocytes degeneration and necrosis. The expression of cTnI increased significantly in diabetic groups compared to control group, and that in model group of 4 weeks increased far more than that in model group of 2 weeks(P<0.05).CONCLUSION: The increased level of cTnI and the change of the heart function may be associated with the development diabetic cardiomyopathy. These changes are valuable for the early clinical diagnosis of myocardial injury in diabetic cardiomyopathy.     

Relationship between 3-nitrotyrosine and myocardial cell apoptosis in rat diabetic cardiomyopathy

AIM: To explore the relationship between 3-nitrotyrosine (3-NT) level in hearts or blood and myocardial cell apoptosis in rat diabetic cardiomyopathy (DCM). METHODS: Sixty Sprague-Dawley (SD) rats (male, 8-week-old) were randomly divided into 4 groups: normal group, diabetic cardiomyopathy group (DCM group), diabetic rats treated with valsartan (40 mg·kg^-1·d^-1, D+V group) and DCM rats treated with valsartan (40 mg·kg^-1·d^-1, DCM+V group). Apoptotic index (AI) of rat cardiac myocytes was examined by TUNEL. The expression index (EI) of 3-NT in rat cardiac myocytes was examined by immunohistochemistry. The 3-NT concentration in rat serum was examined by ELISA. RESULTS: (1) Significant differences of the heart weight indexes among the 4 groups were observed (P<0.01). The heart weight indexes in DCM group and DCM+V group were higher than those in normal group and D+V group (P<0.01). (2) The EI of 3-NT in the cardiac myocytes was positively correlated with the AI of the cardiac myocytes in the same group (P<0.01), but the concentration of 3-NT in blood had no correlation with the AI of cardiac myocytes (P>0.05). (3) The difference of AI of cardiac myocytes among the 4 groups had statistical significance (P<0.01). The arrangement from high to low of AI was DCM group > D+V group and DCM+V group > N group (P<0.05). (4) The EI of 3-NT in DCM group was the highest as compared to other groups (P<0.05). (5) No statistical difference of 3-NT concentration in blood among the 4 groups was observed (P>0.05). CONCLUSION: (1) The expression of 3-NT in DCM myocardial tissues in SD rats is significantly increased and closely correlated with the apoptosis in myocardial cells. Valsartan inhibits 3-NT expression in DCM myocardial cells, thus inhibits the DCM myocardium apoptosis. (2) The 3-NT level in blood can not be true for reflection of 3-NT expression in DCM myocardial tissues and its effect on myocardial cell apoptosis.     

Expression of TGF-β1 and apoptosis in myocardium of diabetic rats

AIM: To study the pathophysiological mechanism of cardiomyopathy, the expression of TGF-β₁ and apoptosis in myocardium of diabetic rats were investigated. METHODS:The diabetes models were established by single intravenous injection of streptozotocin (50 mg/kg) in rats. By the method of immunochemistry, the expression of TGF-β₁ in the cardiomyocytes was detected as the index to evaluate the degree of fibrosis. The method of TUNEL was used to measure the cardiomyocyte apoptosis as the index to explore its importance in process of diabetic cardiomyopathy. RESULTS:① The weight of diabetic rats was apparently lower than that in the rats before the diabetic model was built (P<0.01), and the increase in weight in diabetic rats within three month was less than that in normal group. ② Compared with control group, the concentration of blood glucose was continually elevated during the experiment. ③ The expression of TGF-β₁ in the diabetic cardiac muscle was much more than that in normal group (P<0.01). ④ The apoptosis of myocardium measured by the method of TUNEL was apparent in the diabetic groups than that in normal one (P<0.01). However, no significance was detected in the different courses of diabetic groups. CONCLUSIONS:The apoptosis might play an important role in leading the diabetic cardiomyopathy to heart failure. The expression of TGF-β₁ in the myocardium of diabetic rats was more than that in normal and had an increasing trend in the procession of diabetic cardiomyopathy. TGF-β₁ might be a significant factor in diabetic myocardium fibrosis. Apoptosis might play an important role in the initial stage of diabetes, which promotes the diabetic cardiomyopathy to heart failure.     

Effect of insulin combined with selenium on myocardial remodeling in diabetic rats

AIM: To investigate the effects of insulin combined with selenium on myocardial remodeling in streptozotocin (STZ)-induced diabetic rats.METHODS: The animal model of diabetic cardiomyopathy was induced by intraperitoneal injection of STZ (50 mg/kg) in rats. The level of blood glucose was estimated using One Touch SureStep blood glucose meter. Hemoglobin A1c level was detected by microcolumn assay. Triglyceride and total cholesterol were measured by enzymatic method. Collagen content in the myocardium was determined by Mallory staining. The expression of tumor necrosis factor α (TNF-α) in the serum and myocardium was observed by the methods of ELISA and immunohistochemistry, respectively.RESULTS: Compared with control group, the animals in model group showed metabolic disorders of glucose and lipid, and the cardiac function declined significantly (P<0.01).The myocardial cells showed disorder of distribution, filament breakage and collagen hyperplasia,and serum and myocardial TNF-α levels were significantly elevated.Insulin in combination with selenium significantly decreased the levels of blood glucose and lipid, and markedly inhibited the expression of TNF-α in the serum and myocardium than those in the rats administered with insulin alone (P<0.01).CONCLUSION: Combination of insulin and selenium significantly improves the structure and function of the heart by down-regulation of TNF-α.     

Quercetin inhibits inflammasome activation in diabetic rats and attenuates myocardial injury

AIM:To observed the effect of quercetin on NLRP3 inflammasome activation in the rats with diabetic cardiomyopathy (DCM) and its protective effect on the myocardium. METHODS:Male SD rats (n=40) were randomly divided into normal control group (n=10) and model group (n=30). The rats in model group were intraperitoneally injected with streptozotocin at 60 mg/kg to establish the model of diabetes mellitus (DM). Blood glucose was measured weekly. After 4 weeks, the rats with random blood glucose ≥ 16.6 mmol/L were selected as DM animals. The rats with DM were randomly divided into 3 groups:DM group, DM+vehicle group and DM+quercetin group. The rats in DM+quercetin group were intragastric infusion with quercetin at 100 mg/kg per day. The cardiac function was measured at the end of the 16th week. The methods of Masson staining and HE staining were used to observe the morphological changes of the myocardial tissues. Western blot, ELISA and immunohistochemistry were used to observe the changes of NLRP3, ASC, caspase-1, interleukin (IL)-1β and IL-18. TUNEL staining was used to observe myocardial apoptosis. RESULTS:Quercetin significantly inhibited the activation of NLRP3 inflammasome in the myocardium of the DM rats (P<0.05). The levels of IL-1β and IL-18 in DM+quercetin group were significantly decreased, quercetin reduced cardiac tissue apoptosis, and the cardiac function in DM+quercetin group was significantly improved (P<0.05) compared with DM group and DM+vehicle grpup. CONCLUSION:Quercetin significantly inhibits the activation of NLRP3 inflammasome, and reduces the levels of inflammation and myocardial apoptosis, thus protecting the heart function of DCM rats.     

Effect of hydrogen sulfide on myocardial fibrosis and PPARγ and NF-κB expression in rat model of diabetes

AIM: To explore the effects of hydrogen sulfide (H₂S) on the myocardial fibrosis in a rat model of diabetes and its mechanism.METHODS: Single intraperitoneal injection of streptozotocin (STZ) was utilized to establish a rat model of diabetes. Sodium hydrosulfide was used as an exogenous donor of hydrogen sulfide. Male SD rats were randomly divided into control group, STZ group, STZ+H₂S group and H₂S group. Eight weeks later, HE and VG staining methods were used to observe the collagen distribution and collagen volume fraction was measured by image analysis. The expression levels of type I collagen, PPARγ and NF-κB in the cardiac tissues were determined by Western blotting.RESULTS: Compared with control group, collagen distribution and the expression levels of type I collagen and NF-κB in the cardiac tissues were markedly increased (P<0.05), while PPARγ was significantly decreased in STZ group (P<0.05), but these indexes were reversed significantly in STZ+H₂S group (P<0.05). The expression levels of type I collagen, PPARγ and NF-κB had no significant difference between H₂S group and control group.CONCLUSION: Hydrogen sulfide attenuates cardiac fibrosis in diabetic rats, and its mechanism may be related to PPARγ-NF-κB signaling pathway.     

Water decoction of Platycladus orientalis reduces blood glucose and lipids in mice

AIM: To study the effects of water decoction of Platycladus orientalis on reducing high blood glucose and lipids in diabetic and hyperlipidemia mice, respectively. METHODS: The mouse model of hyperlipidemia was established. The increasing rate of weight, hepatic index, lipid content of liver and atherosclerosis index (AI) were measured. Blood levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), adiponectin (ADP) and interleukin-6 (IL-6) were detected. According to these indexes, the function of water decoction of Platycladus orientalis for reducing high blood lipids caused by hyperlipidemia was evaluated. At the same time, the model of diabetes mellitus was established. The levels of fasting plasma glucose, fasting plasma insulin and blood tumor necrosis factor-α (TNF-α) were measured. The glucose tolerance test was performed. The insulin resistance index was calculated. The function of water decoction of Platycladus orientalis to reduce high blood glucose caused by diabetes was observed by these above indexes. RESULTS: Water decoction of Platycladus orientalis lowered the increasing rate of weight, hepatic index and lipid content of liver, reduced the blood content of TC, TG and IL-6, and elevated the blood HDL-C and ADP content caused by high-fat diet apparently (P<0.05). The effect of water decoction of Platycladus orientalis at high dose was more effective than that at low dose. Water decoction of Platycladus orientalis obviously alleviated the abnormity of glucose tole-rance test, reduced blood TNF-α and insulin levels, and decreased insulin resistance index caused by diabetes apparently (P<0.05). The effect of the drug at high dose was stronger than that at low dose. CONCLUSION: The water decoction of Platycladus orientalis dose-dependently reduces blood glucose caused by diabetes and blood lipids caused by hyperlipidemia in the mice. The mechanism to reduce blood lipids may be related with elevating blood ADP content and reducing blood IL-6 content, and the mechanism to reduce blood glucose may be related with lowering blood TNF-α content.     

Effects of Ginkgo biloba extract on myocardial TGF-β1 and collagen expression and interstitial fibrosis in type I diabetic cardiomyopathy rats

AIM:To study the effects of Ginkgo biloba extract (EGB) on myocardial TGF-β1 and collagen expression and interstitial fibrosis in type I diabetic cardiomyopathy rats. METHODS:Thirty male SD rats were randomly divided into normal control group (CON), diabetes mellitus group (DM) and EGB treatment group (EGB). Streptozocin was intraperitoneally injected into the animals in the latter 2 groups to induce type I diabetic rat model. The rats in EGB group were intraperitoneally injected with EGB. At the end of the 12th week, the body weight of each rat and its left ventri-cular weight, blood glucose, glycosylated hemoglobin and serum insulin concentration were measured. The left ventricular end-diastolic volume (LVEDV), the left ventricular end-systolic volume (LVESV), the left ventricular ejection fraction (LVEF) and the stroke volume (SV) were determined by echocardiography. The content of collagen in left ventricular myocardium, and the expression of transforming growth factor β1 (TGF-β1), procollagen type I and collagen type III were assayed by Sirius red staining, immunohistochemical staining and RT-PCR, respectively. Left ventricular myocardial cells of the neonatal SD rats were isolated and cultured in vitro with low-glucose culture medium (LG group), high-glucose culture medium (HG group) or high-glucose culture medium plus EGB (HG+EGB group). The mRNA levels of TGF-β1, procollagen type I and collagen type III were detected by RT-PCR. RESULTS:Compared with CON group, blood glucose, glycosylated hemoglobin, left ventricular weight index, the content of collagen, and the expression of TGF-β1, procollagen type I and collagen type III in left ventricular myocardial tissues of DM group were significantly increased, while the levels of blood insulin, LVEDV and SV were significantly decreased. However, compared with DM group, blood glucose, glycosylated hemoglobin, left ventricule weight index, the content of collagen, and the expression levels of TGF-β1, procollagen type I and collagen type III in the left ventricular myocardial tissues of EGB-treated rats were significantly decreased, while the levels of blood insulin, LVEDV and SV were significantly increased. Compared with LG group, the mRNA expression levels of TGF-β1, procollagen type I and collagen type III were significantly increased. However, compared with HG group, the mRNA expression levels of TGF-β1, procollagen type I and collagen type III were significantly decreased after treated with EGB. CONCLUSION: EGB retards the process of myocardial fibrosis and improves the cardiac functions in type I diabetic cardiomyopathy rats by down-regulating the expression of TGF-β1, reducing the synthesis and deposition of collagen type I and collagen type III.     

Changes of plasma levels of soluble VEGFR2 and SOD in hypertensive patients and hypertensive diabetic patients

AIM: To explore the changes of plasma levels of soluble vascular endothelial growth factor receptor 2 (sVEGFR2) and superoxide dismutase (SOD) in hypertensive patients and hypertensive diabetic patients. METHODS: In this cross-sectional study, 88 cases were enrolled, which were divided into hypertensive group (n=31), hypertensive diabetic group (n=31) and control group (n=26). Blood pressure was obtained from each participant with mercury sphygmomanometer. The levels of sVEGFR2 and SOD were measured by ELISA. Meanwhile, the levels of plasma glucose, glycosylated hemoglobin A1c (GHbA1c) and lipid profile were detected. RESULTS: The levels of total cholesterol (TC) and body mass index (BMI) were significantly higher in hypertensive group than those in control group (P<0.05). The levels of TC, low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), BMI, waist circumference were significantly higher in hypertensive diabetic group than those in control group (P<0.05). The plasma levels of sVEGFR2 and SOD in both hypertensive diabetic group and hypertensive group were significantly decreased compared with control group (P<0.05), while the mean plasma levels of sVEGFR2 and SOD in hypertensive diabetic group were significantly decreased compared to the hypertensive group (P<0.05). A significantly positive correlation between sVEGFR2 and SOD in the whole study population (P<0.05) was observed. CONCLUSION: The plasma level of sVEGFR2 is decreased in both hypertensive and hypertensive diabetic patients, and more significantly decreased in hypertensive diabetic patients. Decreased SOD level may be associated with to the reduction of sVEGFR2.     

Role of nucleolin on myocardial hypertrophy and fibrosis in type Ⅱ diabetic cardiomyopathy mice

AIM:To investigate the effect of nucleolin on diabetic cardiomyopathy in mice.METHODS:A type Ⅱ diabetic cardiomyopathy mouse model was prepared using a cardiac-specific nucleolin-overexpressing transgenic mice.The mice were divided into wild-type mouse control group,nucleolin transgenic mouse control group,wild-type mouse diabetes group and nucleolin transgenic mouse diabetes group.Wheat germ agglutinin (WGA) fluorescent dye,Masson staining and PowerLab system detection were used to further clarify the role of nucleolin on cardiac hypertrophy,fibrosis and cardiac function in type Ⅱ diabetic cardiomyopathy mice.RESULTS:Compared with wild-type mouse control group,no significant increase in blood glucose level was found,while genetical myocardial cell hypertrophy was significantly attenuated in nucleolin transgenic mouse diabetes group.The collagen fibers were also significantly reduced,and hemodynamic indexes±dp/dt_max,left ventricular end-diastolic pressure,left ventricular systolic pressure and heart rate were also improved.The above differences were statistically significant.CONCLUSION:Nucleolin may reduce the occurrence of myocardial hypertrophy and fibrosis,thus improving the cardiac function of diabetic cardiomyopathy mice.     

Expression and significance of thrombospondin-1 in myocardium of type 2 diabetic cardiomyopathy rats

AIM: To investigate the expression and significance of thrombospondin-1 (TSP-1) in left ventricular myocardium of type 2 diabetic cardiomyopathy (DCM).METHODS: The rat model of DCM was established by eating a high-fat diet together with injection of low dose streptozocin (30 mg/kg) intrapertoneally.After 12 weeks,the content of collagen was quantified by Masson staining.The mRNA level of TSP-1 was determined by quantification real-time RT-PCR,while the protein level of TSP-1 was analyzed by Western blotting and immunohistochemistry.RESULTS: Compared with the control group,the content of collagen in the DCM group was increased greatly (11.01±3.05 vs 16.92±3.18,P<0.01).The mRNA and protein expressions of TSP-1 were significantly higher than those in control group (0.0089±0.0034 vs 0.0141±0.0037,P<0.05；96.38±16.80 vs 129.98±16.96,P<0.05).In DCM group,the mRNA and protein expressions of TSP-1 showed significantly positive correlations with the levels of fasting blood glucose and collagen (r=0.762,P<0.01; r=0.717,P<0.05; r=0.735,P<0.01; r=0.750,P<0.01).There was a significantly positive correlation of TSP-1 mRNA level with LVEDP (r=0.658,P<0.05).In contrast,there was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.605,P<0.05; r=-0.694,P<0.05).There was a significantly positive correlation of TSP-1 protein with LVEDP (r=0.716,P<0.05).There was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.633,P<0.05; r=-0.669,P<0.05).CONCLUSION: The increased expression of TSP-1 may play an important role in the development of myocardial interstitial fibrosis in DCM.     

Piperlongumine protects mice against diabetic cardiomyopathy by alleviating inflammation

AIM:To investigate the effect of piperlongumine (PL) on myocardial injury and fibrosis in diabe-tic cardiomyopathy (DCM) models. METHODS:To imitate cardiomyocytes in a high glucose environment, H9C2 cells were stimulated by high glucose (33 mmol/L), and then the cells were divided into control group, high glucose group, low dose (2.5 μmol/L) of PL group and high dose (5 μmol/L) of PL group. The mRNA levels of inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and the protein levels of pro-fibrotic markers including transforming growth factor-β (TGF-β) and collagen IV were determined. C57BL/6 mice were randomly divided into control group, type 1 diabetes mellitus group, low dose (2.5 mg/kg) of PL group and high dose (5 mg/kg) of PL group. The mice were intraperitoneally injected with streptozotocin at dose of 50 mg/kg for 5 consecutive days. The fasting glucose le-vels higher than or equal to 12 mmol/L meant the establishment of type 1 diabetes mellitus. The treatment with PL was initiated. The fasting blood glucose was detected every 2 weeks. After echocardiography at the 13th week, the mice were killed after anesthesia at the 13th weekend. The blood was collected to measure the serum levels of creatine kinase isoenzyme MB (CK-MB) and lactate dehydrogenase (LDH). The heart tissues were prepared with formaldehyde for 24 h, and was embedded in paraffin for pathological sectioning. HE staining and Sirius red staining were conducted. The morphological changes were observed under microscope. RESULTS:In the H9C2 cell model induced by high glucose, the mRNA expression levels of TNF-α and IL-6, as well as the protein expression levels of TGF-β and collagen IV were significantly higher than those in control group. The above indexes were decreased after PL treatment (P<0.05). PL alleviated the disorder of basic structure, and cardiac fibrosis in the DCM mice. After the administration of PL, the serum levels of CK-MB and LDH were decreased significantly (P<0.05). CONCLUSION:PL is a potential cardioprotective agent in treatment of DCM as it can inhibit inflammation and mitigate the diabetic myocardial injury.     

Effect of atorvastatin on cardiac function and HGF/c-Met signaling pathway after acute myocardial infarction in diabetic rats

AIM: To investigate the effect of atorvastatin on myocardial apoptosis, ventricular remodeling and cardiac function after acute myocardial infarction (AMI) in diabetic rats, and to explore whether the effect is mediated by hepatocyte growth factor (HGF)/c-Met signaling pathway. METHODS: Diabetes in 70 male SD rats was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). After 8 weeks, AMI was induced by the ligation of the left anterior descending coronary artery in the diabetic rats, and 32 surviving rats were divided into AMI group (n=16) and AMI＋atorvastatin group (n=16, 20 mg·kg-1·d-1) at random. The similar surgical procedure was completed in sham group (n=11) without coronary ligation. Atorvastatin was given daily by gavage from the first day after AMI. Two weeks later, the cardiac function, pathological changes of myocardial tissues, myocardial apoptosis, and the expression of HGF and c-Met were compared among groups. RESULTS: AMI significantly reduced cardiac function, increased collagen volume fraction (CVF) and myocardial apoptotic index, and up-regulated the expression of HGF and c-Met at mRNA and protein levels in AMI control group (P<0.05). The cardiac function was improved, and CVF and myocardial apoptotic index were reduced by the treatment with atorvastatin, which also up-regulated the expression of HGF and c-Met (P<0.05). CONCLUSION: Atorvastatin significantly attenuates myocardial apoptosis and cardiac remodeling, and improves cardiac function after AMI in diabetic rats by further enhancing the activation of HGF/c-Met pathway.     

Effects of icariin on expression of transforming growth factor β1 and type Ⅳ collagen in diabetic rat testis

AIM: To determine the beneficial effects of icariin on streptozotocin (STZ)-induced diabetic testopathy in rats. METHODS: The diabetic animal model was induced in male Sprague-Dawley rats by an injection of streptozotocin (40 mg/kg, iv). The rats were randomly divided into 3 groups: control group, model group and icariin (80 mg/kg, ig) group. Twelve weeks after injected with streptozotocin, all rats were anaesthetized and killed to remove the testes from scrotum. Serum concentrations of glucose and testosterone, and the levels of succinate dehydrogenase (SDH), acid phosphatase (ACP), γ-glutamyl transpeptidase (γ-GT) and lactate dehydrogenase (LDH) in testes were measured. The morphology of the testicular tissues was observed under light microscope. Immunohistochemistry was employed to determine the protein levels of TGF-β₁ and type Ⅳ collagen. RESULTS: Compared with control group, the content of serum glucose increased while the serum level of testosterone and the activitiy of SDH, ACP, γ-GT and LDH in testis decreased in model group (P<0.01). The histopathological examination showed that the diameters of seminiferous tubules and various grades of spermatocytes in the testis were markedly decreased. Compared with control group, the expression of TGF-β₁ and collagen Ⅳ was significantly increased in model group. These alterations were significantly attenuated in icariin group (P<0.01). CONCLUSION: Icariin evidently relieves testicular damage in rats with diabetic testopathy by improving the secretion of testosterone and reducing the expression of TGF-β₁ and collagen Ⅳ at protein level.     

Serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy patients

AIM: To investigate the serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy (DR) patients.METHODS: One hundred and ten cases of type 2 diabetic patients were divided into 3 groups: no diabetic retinopathy group (DM, n=35), non-proliferative diabetic retinopathy group (NPDR, n=45), and proliferative diabetic retinopathy group (PDR, n=30). Other 40 normal persons served as controls (NC group). The physical examinated was performed for each patient. Serum levels of fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c), 2 h postprandial plasma glucose (2hPG), fasting insulin (FINS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), adiponectin, intercellular adhesion molecule-1(ICAM-1), tumor necrosis factor-α (TNF-α) and high-sensitivity C-reactive protein (hs-CRP) were measured. Insulin resistance index (HOMA-IR) was also calculated.RESULTS: The systolic blood pressure, body-mass index, waist-hip ratio, serum levels of TG, LDL-C, FPG, 2hPG, HbA1c, ICAM-1, TNF-α, hs-CRP and HOMA-IR were significantly higher in DM group, NPDR group and PDR group than those in NC group (P<0.05). The systolic blood pressure, serum levels of ICAM-1, TNF-α, hs-CRP and HOMA-IR were higher in NPDR group and PDR group than those in DM group (P<0.05). The serum concentration of adiponectin was lower in DM group, NPDR group and PDR group than that in NC group (P<0.05), and that was also lower in NPDR group and PDR group than that in DM group (P<0.05). The negative correlations between adiponectin and ICAM-1 (r=-0.735,P<0.01), TNF-α (r=-0.781,P<0.01), hs-CRP (r=-0.768, P<0.01) or HOMA-IR (r=-0.752, P<0.01) were observed. The relationships between HOMA-IR and ICAM-1 (r=0.857,P<0.01), TNF-α (r=-0.906, P<0.01) or hs-CRP (r=-0.888,P<0.01) were positive.CONCLUSION: The results suggest that inflammatory refactors and adiponectin play important roles in the pathophysiology and progression of DR. The protective effects of adiponectin on DR may be related with its anti-inflammatory reactions to improve insulin resistant.     

Dynamic expression of S-adenosyl-L-homocysteine hydrolase under intervention of fimasartan in early stage of type 2 diabetic cardiomyopathy rats

AIM: To detect the changes of S-adenosyl-L-homocysteine hydrolase (SAHH) signaling pathway and related proteins under the intervention of fimasartan (FIM) in rats with diabetes mellitus (DM), and to explore the pathological mechanism of the occurrence and development of diabetic cardiomyopathy (DCM). METHODS: The type 2 diabetic rat model was established by injection of streptozocin after 5-week high-fat diet. The rats were randomly divided into control group, DM group, and DM+FIM group. Fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and fasting insulin (FINS) levels were tested. M-mode echocardiography was performed for determining the heart functions. High-performance liquid chromatography (HPLC) was used to detect homocysteine (Hcy), S-adenosylmethionine (SAM) and S-adenosyl-L-homocysteine (SAH). The alteration of SAHH in myocardium was determined by Western blot. RESULTS: The success rate of type 2 diabetic rat modeling was 84%. Compared with DM group, the body weight of the rats in DM+FIM group increased significantly (P<0.05), while cardiac index, left ventricular index, FBG and LDL-C were significantly reduced (P<0.05). The results of echocardiography showed that ejection fraction increased (P<0.05) in DM+FIM group. HPLC detection showed that the level of Hcy and the ratio of SAM/SAH were significantly reduced (P<0.05). The results of Western blot showed that the expression of SAHH in DM group was increased compared with control group, while that in DM+FIM group declined (P<0.01). CONCLUSION: The expression of SAHH, Hcy and other related factors may be important during the occurrence and development of early DCM, and FIM may play a role in this process as an inhibitor of SAHH.     

Protective effect of DIZE on heart function of rats with diabetic cardiomyopathy

AIM: To observed the protective effect of diminazene aceturate (DIZE), an angiotensin-converting enzyme 2 (ACE2) activator, on rats with diabetic cardiomyopathy (DCM). METHODS: Male Wistar rats (n=30) were randomly divided into normal control group, DCM group and DIZE treatment group (DIZE group). The rats in DCM group and DIZE group were intraperitoneally injected with streptozotocin (65 mg/kg) to establish diabetic model. After 12 weeks, the diabetic rats were infused with DIZE at 15 mg·kg^-1·d^-1 or the same volume of saline for 4 weeks using osmotic minipump. The cardiac function was measured at the end of the 16th week. The methods of Mason staining and HE staining were used to observe the morphological changes of the myocardial tissue. Western blot, ELISA and immunohistochemistry were used to observe the changes of ACE2, angiotensin (Ang)Ⅱ, Ang-(1-7), interleukin (IL)-1, IL-6 and connective tissue growth factor (CTGF). RESULTS: DIZE significantly improved the expression of ACE2 in diabetic rats (P<0.05). Compared with DCM group, the levels of IL-1 and IL-6 in DIZE group were significantly decreased, and the cardiac function in DIZE group was significantly improved (P<0.05). CONCLUSION: ACE2 endogenous agonist DIZE significantly increases the ACE2 level and reduces the level of inflammation, thus protecting the heart function of DCM rats.     

Effects of Shenmai injection on myocardial fibrosis in rat model of diabe-tic cardiomyopathy

AIM：To explore the effects of Shenmai injection on myocardial fibrosis in a rat model of diabetic cardiomyopathy (DCM). METHODS：Wistar rats (n=30) were randomly divided into control group, diabetes group and treatment group. Single intraperitoneal injection of streptozotocin was utilized to establish a rat model of DCM. The rats with DCM in treatment group were intraperitoneally injected with Shenmai injection. Ventricular cannulation was applied to assess the cardiac functions. The formation of collagen in the cardiac tissues was assessed by Masson staining. The generation of reactive oxygen species (ROS) in the cardiac tissues was detected by dihydroethidium staining. The expression levels of matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinase 2 (TIMP-2) and collagen I in the cardiac tissues were determined by Western blotting. RESULTS：Compared with control group, the cardiac functions were deteriorated in diabetes group (P<0.05), which was improved in treatment group as compared with diabetes group (P<0.05). Compared with control group, the formation of collagen and ROS increased significantly in diabetes group (P<0.05), which was decreased in treatment group as compared with diabetes group (P<0.05). Compared with control group, the expression level of MMP-2 in the cardiac tissues was deceased and TIMP-2 was increased significantly in diabetes group (P<0.05), but reversed significantly in treatment group (P<0.05).CONCLUSION:Shenmai injection attenuates cardiac fibrosis in the rats with DCM by inhibiting the generation of ROS.     

Aerobic exercise protects cardiac function of T2DM mice by activation of PI3K (p110α)/Akt signaling pathway

AIM: To study the protective effect of aerobic exercise on cardiac dysfunction in mice and its mechanism, and to provide theoretical and practical basis for the exercise therapy of diabetic cardiac dysfunction.METHODS: The mice were divided into normal control non-exercise (NNC) group, normal control exercise (ENC) group, diabetic non-exercise (NDM) group and diabetic exercise (EDM) group. At the end of the experiment, the cardiac function was evaluated by echocardiography. The pathological changes of the myocardial tissues and the development of fibrosis were observed. The mRNA expression of ANP, and the protein levels of PI3K (p110α) and Akt were determined. RESULTS: The decrease in cardiac function of diabetic mice was observed, and the cardiac function recovered after exercise intervention (P<0.05). Under light microscope with HE and Masson staining, the myocardial structure in NDM group was in extreme disorder, cell arrangement was not neat, and the degree of fibrosis increased, but the myocardial damage was improved in ENC group. Compared with NNC group, the mRNA expression of ANP in the myocardium of diabetic mice was up-regulated (P<0.05). The protein levels of PI3K (p110α) and Akt were decreased (P<0.05), and the cascade was inactivated. Compared with NDM group, the mRNA expression of ANP was down-regulated and the protein levels of PI3K (p110α) and Akt were up-regulated in EDM group (P<0.05). CONCLUSION: Diabetes results in myocardial damage in mice, and reduces cardiac function. Exercise intervention alleviates the heart dysfunction induced by high glucose via activating PI3K(p110α)/Akt signaling pathway to protect the structure and function of the myocardium.     

Effects of extract of Ginkgo biloba on cognitive function and apoptosis of hippocampus neuronal cells in type 1 diabetic rats

AIM: To investigate the protective mechanism of extract of Ginkgo biloba (EGB) on apoptosis of hippocampus neuronal cells in type 1 diabetic encephalopathic rats. METHODS: Thirty-six male Sprague-Dauley rats were divided into 3 groups: control group, diabetic group and EGB-treated group. Streptozotocin was injected intraperitoneally to the animals in later two groups to induce diabetes. The rats in EGB-treated group were injected intraperitoneally with EGB, and the same volume of normal saline was injected to the rats in other groups. At the end of the 12th week, the spatial learning and memory abilities of rats in each group were examined by Morris water maze test. Blood glucose and serum insulin concentration were measured. The neuron densities in hippocampus were measured by Image-Pro Plus 6.0 software. The expressions of Bax, Bcl-2, caspase-3 were assayed by Western blotting and immunohistochemistry. RESULTS: Compared to control group, the level of blood glucose (P<0.01), the protein expression of Bax (P<0.01) and caspase-3 (P<0.01) in hippocampus neuronal cells, and the ratio of Bax/Bcl-2 (P<0.01) and the escape latency (P<0.01) in diabetic group, were significantly increased, while the serum insulin concentration (P<0.01), the neuronal density (P<0.05) in CA1,CA2 hippocampal regions and the platform searching score (P<0.01) were significantly deceased. After treated with EGB, the serum insulin concentration (P<0.05), the neuronal density (P<0.05) in CA1,CA2 hippocampal regions and the platform searching score (P<0.01) were significantly increased, while the level of blood glucose (P<0.01), the protein expression of Bax (P<0.05), caspase-3 (P<0.05) in hippocampus neuronal cells, the ratio of Bax/Bcl-2 (P<0.01) and the escape latency (P<0.05) were significantly deceased than those in diabetic group. The protein expression of Bcl-2 in hippocampus neuronal cells did not alter in any experimental rats. CONCLUSION: EGB improves the spatial learning and memory capacity in diabetic rats by decreasing the expression of Bax, Bax/Bcl-2 ratio and down-regulating caspase-3 to reduce neurocyte apoptosis and increase the neuron density in CA1, CA2 hippocampal regions, suggesting that effective regulation of neuron apoptosis associated genes may be one of the mechanisms for EGB to treat diabetic encephalopathy.