Change Of Erbb2 Expression And Phospho-Erbb2 Level In Diabetic Cardiomyopathy Rats

Objectives To explore the change of ErbB2 mRNA expression and phospho- ErbB2 level in the cardiac tissue of diabetic rats.Methods 36 male SD rats were randomly divided into 4 weeks diabetic group , 4 weeks control group , 12 weeks diabetic group and 12 weeks control group. Diabetic rat model was induced by a single intraperitoneal injection of STZ(55mg/kg). Heart weight (HW) ,body weight (BW) / heart weight (HW), left ventricular end diastolic dimension(LVEDD), left ventricular end systolic dimension(LVESD), left ventricular ejection fraction(LVEF), higher frational shortening(LVFS), heart rate(HR),collagen volume fraction(CVF), myocardium glycogen content , ErbB2 mRNA expression and Phospho-ErbB2 level were observed at 4 weeks and 12 weeks respectively after the STZ administered.Results Compared with 4 weeks control group, HW/BW significantly increased in 4 weeks diabetic group [(3.41±0.12)mg/g vs. (2.32±0.22)mg/g, P<0.01]. Compared with 12 weeks control group , HW/BW significantly increased in 12 weeks diabetic group [(3.72±0.38)mg/g vs. (2.39±0.26)mg/g, P<0.01]. CVF significantly increased in 4 weeks diabetic group and 12 weeks diabetic group [4.48%±0.21% vs. 2.79%±0.36%,P<0.01; 15.29%±0.67% vs. 3.01%±0.13%, P<0.01]. Myocardium glycogen content significantly increased in 4 weeks diabetic group and 12 weeks diabetic group[2.66%±0.34% vs. 1.72%±0.33, P<0.01; 7.90%±0.69% vs. 2.05%±0.45%, P<0.01] . There was no statistical significance in left ventricular ejection fraction(LVEF) and Left ventricular systolic dimension(LVESD) between 4 weeks diabetic group and 4 weeks control group.Heart rate was decreased in 4 weeks diabetic group[(333.0±34.3)bpm vs.(417.0±81.5)bpm, P<0.05] and 12weeks diabetic group[(213.0±16.7)bpm vs. (391.0±47.9), P<0.01].There was no statistical significance in the expression of ErbB2 mRNA and phospho- ErbB2 level between 4 weeks diabetic group and 4 weeks control group. Compared with 12 weeks control group , left ventricular ejection fraction(LVEF) decreased in 12 weeks diabetic group [72.50%±3.81% vs. 82.60%±2.97%, P<0.01]. Compared with 12 weeks control group ,Left ventricular systolic dimension(LVESD) increased in 12 weeks diabetic group [(3.57±0.232) mm vs. (3.06±0.376)mm,P<0.05].The expression of ErbB2 mRNA and phospho- ErbB2 level significant decreased in 12 weeks diabetic group [(0.73±0.220) vs. (1.055±0.330), P<0.05;(0.875±0.013) vs. (0.950±0.018), P<0.01]. The expression of ErbB2 mRNA positively correlate with Left ejection fraction (r=0.798, P<0.01). The phospho- ErbB2 level positively correlate with Left ejection fraction(r=0.720, P<0.01).The expression of ErbB2 mRNA negatively correlate with CVF(r= - 0.663, P<0.01). The phospho- ErbB2 level negatively correlate with CVF(r=-0.931, P<0.01 ).Conclusions At 12weeks after the Streptozotocin administered , the diabetic group cardic funtion decreased and myocardial became hypertrophy. Also myocardial mesenchyme and glycogen deposition significantly increased in the diabetic group. These changes consistent with the character of diabetic cardiomyopathy. The expression of ErbB2 mRNA and phospho- ErbB2 level significantly decreased in diabetic cardiomyopathy .Reduced ErbB2 expression and ErbB2 signal conduction may be involved in the progression of diabetic rat cardiomyopathy.