Expression increase of chymase gene in diabetic hamsters / 基础医学与临床

ABSTRACT

Objective To explore how does chymase affect diabetic cardiomyopathy by investigating the gene expression of chymase and the relationship between the gene expression of chymase and the angiotensin Ⅱ in the cardiomyopathy of streptozotocin-induced diabetic hamasters. Methods Diabetic hamsters were induced by intraperitoneal injection of STZ 40 mg/kg once a day for 3 days. After stabilization of diabetic state for 18 weeks, the myocardial ultrastructure was observed with electron microscope and pathologic changes were observed by light microscopy. Immunohistochemistry was used to measure the level of expression of type Ⅰ and type Ⅲ collagen in diabetic and normal hamster hearts. Level of blood glucose, lipoprotein was determined using biocehemical methods. Apoptosis of cardiomyocyte was measured using TUNEL methods. Radioimmunuoassay method was used to determine the level of angiotensin Ⅱ. RT-PCR was used to determine chymase gene expression (corrected by?-actin). ResultsComparing with the control group, levels of serum glucose, TG, TC, LDL in DM group were much higher. Concentrations of collagen Ⅰ, Ⅲ and angiotensin Ⅱ [(95.8?16.0)?g/kg tissue vs (51.1?20.8)?g/kg tissue] in myocardial tissue in DM group were much higher than those in control group. RT-PCR result showed Comparing with the control group, the mRNA expression of chymase in DM group was promoted significantly (0.810?0.026 vs 0.490?0.087). Conclusion In diabetic hamsters, the gene expression of chymase were much higher than thatin the control group, accompanying higher level of Angiotensin Ⅱ, higher levels of expression of collagen Ⅰ and Ⅲ. This result suggests that chymase plays an important role in the diabetic cardiomyopathy by promoting the activity of chymase.