| Objective To observe the pathological and functions changes and microthrombosis in the cardiac and renal tissue of rats by developing a rat model of type 2 diabetes ; Detecting the expression of fibrinogen-like protein 2 prothrombinase (fgl2) in myocardium and renal tissue of diabetic rats (DM) and analyzing the relation of fgl2 prothrombinase and microthrombosis to investigate the possible mechanism and significance of diabetic microthrombosis.Methods The rats were randomly divided into control group and diabetic group. The model group was induced to type 2 diabetes by diets enriched with glucose and fat and intraperitoneal injection with streptozoticin(STZ).The pathological changes in the cardiac tissue and renal tissue of rats were observed at 19th week,23rd week and 28th week of experiment respectively. The maximal velocity decrease of pressure per second in left ventricle within the period of isovolumic relaxation (- dp/ dtmax) and the maximal velocity increase of pressure per second in left ventricle within the period of isovolumic contraction (+dp/dtmax) were detected by hemodynamics measurement. The ejection fraction of left artrium (EF %) were calculated automatically and heart rate (HR) was constantly monitored and recorded during echocardiography. The ratios of heart weight to body weight (HW/BW) were caculated. The hearts were collected and examined by Hematoxin-eosin(HE) staining,Masson staining and modified MSB staining, the amount of arterioles with microembolization was calculated .The expression of fgl2 in myocardium was examined by RT-PCR and immunohistochemistry. A correlation analysis between the amount of arterioles with microthrombus and the expression of fgl2 was done finally. Meanwhile, the 24-hour proteinuria,serum creatinine(SCr),urea nitrogen(BUN),the ratios of kidney weight to body weight(KW/BW) were determined respectively and the different period of experiment. The renal tissue examined by Hematoxin-eosin(HE) staining,Periodic Acid Schiff(PAS) staining and Masson staining to observe the renal pathologic changes. The proportion of microembolization area to per unit renal glomerulus area was calculated. Renal expression of fgl2 prothrombinase was detected by RT-PCR and immunohistochemical method. Correlativity between the proportion of microembolization area to per unit renal glomerulus area and the expression of fgl2 prothrombinase protein was analyzed.Results①Insulin resistance was induced by feeding diets enriched in sucrose and fat, and hyperglycemia was induced with a dose of STZ that did not cause diabetes in chow-fed rats. After 8 weeks, rats of model group presented itself early changes of diabetic mellitus with the development of diabetes. Compared with those of control group,±dp/dtmax,the ejection fraction,heart rate of diabetic rats were decreased and the ratio of heart weight to body weight,the 24-hour proteinuria,serum creatinine,urea nitrogen,the ratio of kindney weight to body weight of diabetes rats were increased.②The expression of fgl2 was significantly increased in all age groups of rats with diabetes and the fgl2 expression was detected in microvascular endothelial cell of myocardium. Histopathology displayed severe interstitial fibrosis,coagulation necrosis and microembolization in the myocardial tissue of diabetic group. Modified MSB staining showed the microthrombus was primer thrombus that was composed of cellulose. No fgl2 protein expression was detectable in control rats, which showed normal histological structure. Microthrombus in DM group were significantly more than those in control group. There was a significant correlation between the expression of fgl2 and the amount of arterioles with microembolization in DM group, but no significant correlation in control group.③The expression of fgl2 prothrombinase in renal tissue of diabetic rats were increased.Fgl2 prothrombinase expression was detected in microvascular endothelial cell of renal glomerulus and renal interstitium. Typical morphological changes in the model included glomerular hypertrophy,mesangial expansion,thickening of glomerular basement membrane and microembolization in the renal tissue of diabetic group. The proportions of microembolization area to per unit renal glomerulus area of model group were higher than the normal group. Positive correlation was found between fgl2 prothrombinase expression and the proportion of microembolization area to per unit renal glomerulus area.Conclusions①Microthrombosis in cardiac and renal tissue of diabetes mellitus can be observed by the rat model of type 2 diabetes,which provide a good platform of experiment to study the diabetic microvessel complications.②The expression of fgl2 prothrombinase mRNA and protein was increased in myocardium and renal tissue of DM rats ; The compact relation of fgl2 prothrombinase and in situ thrombus in cardiac and renal microvessels of diabetes rats was verified.③It's obvious that heart and kidney in rats of type 2 diabetes mellitus were impaireded, which showed fgl2 prothrombinase may play an important role in the pathogenesis of diabetic microangiopathy by primary microembolization in myocardium and renal tissue. |
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