ATM:To explore the expression of neuregulin - 1 ( NRG - 1 ) at mRNA and protein levels in the myocardial tissues of diabetic rats. METHODS: Forty - five male SD rats were randomly divided into diabetic groups of the 4th, 8th and 12th weeks ( 4th, 8th and 12th DM groups ) and control groups of the 4th, 8th and 12th weeks ( 4th, 8th and 12th C groups ). Diabetic rat model was induced by a single intraperitoneal injection of streptozotocin ( STZ ) at a dose of 55 mg/kg. Echocardiographic parameters, collagen volume fraction ( CVF ), and the mRNA and protein expression levels of NRG - 1 were observed at the 4th, 8th and 12th weeks after STZ injection. RESULTS: No statistical significant difference of the echocardiographic parameters, CVF, and the mRNA and protein expression levels of NRG - 1 between 4th DM group and 4th C group was observed. Compared with 8th C group, left ventricular systolic dimension ( LVESD ) and CVF significantly increased in 8th DM group. No statistical significance of left ventricular fractional shortening ( LVFS ), left ventricular ejection fraction ( LVEF ), and the mRNA and protein expression levels of NRG - 1 between 8th DM group and 8th C group was found. Compared with 12th C group, LVESD and CVF increased, while LVFS and LVEF significantly decreased in 12th DM group. The mRNA and protein expression levels of NRG - 1 in 12th DM group were much lower than those in 12th C group ( 0. 073 ±0.008 vs 0.156 ±0.010 and 0. 171 ±0.054 vs 0. 324 ± 0. 039, both P<0. 01 ). CONCLUSION : The mRNA and protein expression levels of NRG - 1 in the myocardial tissues of diabetic rats are down - regu-lated,which may play some roles in the progression of diabetec cardiomyopathy.%目的:探讨neuregulin-1(NRG-1)在糖尿病大鼠心肌组织中的表达.方法:45只雄性SD大鼠随机分为4周、8周和12周糖尿病组(4th、8th 和12th DM组),4周、8周和12周对照组(4th 、8th 和12th C组).腹腔注射链脲佐菌素诱导糖尿病模型.在诱导糖尿病后第4、8和12周用超声诊断仪评估大鼠心功能,计算心肌胶原容积分数(CVF),免疫组化观察NRG-1在心肌的表达部位,RT-PCR和Western blotting检测NRG-1 mRNA及蛋白的表达水平.结果:4th DM组大鼠心功能指标、心肌CVF、NRG-1 mRNA及蛋白的表达与4thC组相比,差异无统计学意义(P>0.05);与8th C组相比,8th DM组左室收缩末内径(LVESD)和心肌CVF均增高,但左室短轴缩短率(LVFS)、左室射血分数(LVEF)、心肌NRG-1 mRNA及蛋白的表达仍未见明显改变(P>0.05).与12th C组比较,12th DM组LVESD和心肌CVF均显著增高,而LVFS和LVEF显著降低(均P<0.01).12th DM组心肌NRG-1 mRNA及蛋白的表达较同期对照组显著下调(0.073±0.008 vs 0.156±0.010,0.171±0.054 vs 0.324±0.039,均P<0.01).结论:NRG-1在糖尿病大鼠心肌组织中的表达显著下调,这可能参与了糖尿病心肌病的发生和发展.
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