| Objectives: Diabetes Mellitus is a common disease which influences human health, and the risk of congestive heat-failure in diabetic patients is more than healthy people. It is clear that the diabetic cardiomyopathy is a important reason. The clinic expression of the diabetic cardiomyopathy is the disorder of relaxation and (or) contraction in myocardial muscle, which is associated with the concentration of Calcium in cell, and the sarcoplasmic reticulum plays important role. The focal points of researches at present are the influences of the relaxation and contraction in myocardial when the activity of SERCA changes, and another focal points are the influential factors to SERCA. The results display: In diabetic states, the oxidative stress is stranger, then the function of SERCA is influences, and the concentration of Calcium in cell is disturbance, and leads to cardiomyopathy. The research is divided into 4parts:1 To establish the model of diabetic rats: under the standard environment, STZ were injected into the rats, the model was consisted successful through the clinical symptom and vein glucose.2 To investigate the pathologic changes of myocardium in diabetic rats by LM: To embed the tissues which fixed by formalin in paraffin, section them into slice, stain them by hematoxylin and eosin, then take photos through light micrographic.3 In order to observe the activity of cardiac sarcoplasmic reticulum Ca++-ATPase,super-oxide dismutase (SOD) and glutathion peroxidase(GSH-Px),the medium production of oxidative stress injury—malondialdehyde(MDA) in diabetic rats.4 To investigate the gene expression of SERCA2а.Methods: At the base of animal models of diabetic rats, four parameters are observed by the use of biochemistry,molecule-biology and experimental pathology technology. These parameters were as follows: the pathologic changes of myocardium in diabetic rats under LM,the alterations of the activity of SERCA,the changes of mRNA expression level and the changes of the productions associated with oxidative stress and the activity of anti-oxidase. This study consisted of four parts1 50 SD rats were fed adaptively for 7days, then divided them randomly into diabetic group (D group) and normal control group (N group), there were 20 rats in N group and 30 rats in D group, divided N group and D group into N4,N8,D4,D8 group randomly. There were 12 hours before the establishment of the model. In this period, there was no food but water for the rats and through night. Rats in D group were injected STZ(60mg/kg) which had been mixed in citric acid buffer (0.05M,PH=4.5); The rats in N group were injected citric acid buffer with the same volume. 72 hours after the injection, the vein blood and urine of the rats were took to detect the blood and urine glucose. The criterion of diabetic rat was: the blood glucose must be more than 16.7mmol/l, and the urine glucose≥+++, and they ate more, drunk more and the urine of them was more than N group . Detected the body-weight and blood glucose of the rats once a week, and 12 hours before the establishment, they were fed no food but water. All the rats were fed in individual cage, and they were permitted to eat and drink by themselves. They were observed for 8 weeks, and were not treated by insulin. There were 2 rats in D group were knocked-out experiment for the glucose of them<16.7 mmol/L, and 4 rats were dead for infection and ketotic acidot.2 The Pathologic alterations of myocardium were observed under LM by using HE: To embed the tissues which fixed by formalin in paraffin, section them into slice, stain them by hematoxylin and eosin, then take photos through light micrographic.3 The evaluation of the activity of SERCA,MDA,SOD and GSH-Px: The myocardium of 4-week-group and 8-week-goup rats(included diabetic rats and normal rats)were took, and were pulverized into homogenate which density was 10%. To determinate the activity of SERCA, the homogenate were centrifugated in high speed to reperated the sarcoplasmic reticulum , the biochemistry used to assay the activity of SOD, GSH-Px and MDA.4 The expression of SERCA2αgene in DM rats: 100 kg fresh muscle which preserved in -80℃were took, the total RNA were extracted by using Trizol one-step-method, the RNA was reversed into cDNA, the cDNA was amplificated and different prime were mixed in PCR to amplificated the target gene SERCA2αand house geneβ-actin, the electrophoretic bands were observed, and the ratios of the intension target gene to house gene were calculated.Results: 1 It was believed that the model of diabetic rats was established successfully, for it was observed that: rats in diabetic group ate more, drunk more, but the weight of them decreased. The blood glucose of diabetic rats was more than 16.7 mmol/L and the urine glucose≥+++. Then the conclusion was that the modal of diabetic rats was successful.2 Compared with normal rats, there was no pathological changes of myocardium in 4-week-DM rats, but in 8-week-DM rats, the changes were obviously: the swollen cardiac muscle cells,the pyknotic nucleoli,the hyperchromatic nucleus and the hyalined small arteries.3 Compared with normal control rats, the activity of SERCA,SOD and GSH-Px were descending in diabetic rats, and it was more obvious in 8-week-DM rats. But the quantity of MDA was ascending in diabetic rats, and it was more obvious in 8-week-DM rats.4 Compared with normal control rats, the gene level results indicated: the level of SERCA2αwas decreased in 4-week-DM rats and in 8-week-DM-rats, and it was more obvious in 8-week-DM rats.Conclusions: 1 The model of diabetic rat can be successfully established by injecting STZ.2 There were pathological changes in DM rats: the swollen cardiac muscle cells,the pyknotic nucleoli,the hyperchromatic nucleus and the hyalined small arteries.3 The level of oxidative stress in diabetic rats was increased, and the ability of anti-oxidase was descending, there was peroxidative injury in the cardiac muscle of diabetic rats.4 The activity of SERCA and the mRNA were descending in diabetic rats, and as the extending of the course of the disease, the decreasing was more obviously. The regulation of Ca++ was abnormal, the relaxation and contraction of cardiac muscle was injury, cardiomyopathy arose.
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