The Expression Of ErbB4 In Myocardial Tissue Of Diabetic Cardiomypathy Rats

Objectives To investigate the changes of ErbB4 expression and Phospho-ErbB4, and to explore the role of ErbB4 in cardiomyopathy of diabetic rats.Methods 36 male Sprague Dawley (SD) rats (8 weeks), were divided into four groups: 4 weeks control group (n=6), 4 weeks diabetes group (n=12), 12 weeks control group (n=6) and 12 weeks diabetes group (n=12). Streptozotocin- induced (55mg/kg) diabetic rats were adopted. Body weight (BW) / heart weight (HW), echocardiographic parameters, HE staining, collagen content, glycogen content, ErbB4 mRNA expression and Phospho-ErbB4 level were observed at 4 weeks and 12 weeks respectively after the STZ administered.Results Compared with rats in control group, both left ventricular fractional shortening (LVFS) and heart rate (HR) of diabetic rats were significantly decreased at 4 weeks after the STZ administered [45.2%±4.79% vs. 52.3%±4.50%, P<0.05; (333±34.3)bpm vs. (417±81.5)bpm, P<0.05] , HW/BW of diabetic rats and myocardium mesenchyme fibrosis and myocardium glycogen deposition were significantly increased at 4 weeks after the STZ administered [(3.41±0.12)mg/g vs. (2.32±0.22)mg/g, P<0.01; 4.48%±0.21% vs. 2.79%±0.36%, P<0.01; 2.66%±0.34% vs. 1.72%±0.33, P<0.01]; Compared with rats in control group at 12 weeks, left ventricular end systolic dimension and HW/BW and myocardium mesenchyme fibrosis and myocardium glycogen deposition of diabetic rats were significantly increased [(3.57±0.232)mm vs. (3.06±0.376)mm , P<0.05; (3.72±0.38)mg/g vs. (2.39±0.26)mg/g, P<0.01; 15.29%±0.67% vs. 3.01%±0.13%, P<0.01; 7.90%±0.69% vs. 2.05%±0.45%, P<0.01], but left ventricular ejection fraction(LVEF) and LVFS and HR of diabetic rats and ErbB4 mRNA expression and Phospho-ErbB4 level in the left ventricle of diabetic rat's myocardium were significantly decreased [72.5%±3.81% vs. 82.6%±2.97%, P<0.01; 41.1%±3.91% vs. 52.3%±8.37%, P<0.05; (212±16.7)bpm vs. (391±47.9)bpm, P<0.01; 0.51±0.16 vs. 0.99±0.17, P<0.01; 0.931±0.016 vs. 1.012±0.011, P<0.01]. Correlation analysis indicated that LVEF negatively correlated with myocardium mesenchyme fibrosis and myocardium glycogen deposition (r₁=-0.804, P<0.01; r₂=-0.803, P<0.01), positively correlated with ErbB4 mRNA expression and Phospho-ErbB4 level in the left ventricle of diabetic rat's myocardium (r₃=0.666, P<0.01; r₄=0.754, P<0.01); LVFS negatively correlated with myocardium mesenchyme fibrosis and myocardium glycogen deposition (r₅=-0.590, P<0.01; r₆=-0.565, P<0.01), positively correlated with ErbB4 mRNA expression and Phospho-ErbB4 level in the left ventricle of diabetic rat's myocardium (r₇=0.480, P<0.05; r₈=0.553, P<0.01). Conclusions STZ-produced diabetic rat model at 12 weeks, cardiac function significantly decreased, cardiac hypertrophy, myocardium mesenchyme significant fibrosis, myocardium glycogen deposition significantly, consistent with the character of diabetic cardiomyopathy. Myocardium mesenchyme fibrosis and myocardium glycogen deposition decrease cardiac function, while ErbB4 expression and Phospho-ErbB4 are decreased. Reduced ErbB4 expression and ErbB4 signal conduction may be involved in the progression of diabetic rat cardiomyopathy.