3-硝基酪氨酸与糖尿病心肌病大鼠心肌细胞凋亡的关系研究

目的：探讨2型糖尿病大鼠心肌组织及血中3-硝基酪氨酸（3-NT）与糖尿病心肌病（DCM）心肌细胞凋亡的关系。方法：选取8周龄雄性SD大鼠60只，将其随机分为4组，空白对照组、DCM组、糖尿病+缬沙坦处理组和DCM+缬沙坦处理组，每组15只。用TUNEL法检测DCM心肌细胞的凋亡指数（AI）；用免疫组化的方法检测心肌组织中3-NT的表达指数（EI）；用ELISA法检测血清中3-NT的浓度。结果：(1) 4组大鼠的心脏重量指数有显著差异（P<0.01），DCM组和DCM+缬沙坦处理组心脏重量指数大于空白对照组和糖尿病+缬沙坦处理组。(2) 心肌组织免疫组化方法检测表明，心肌组织中3-NT的EI与心肌细胞的AI呈正相关（P<0.01），而血中3-NT的含量与心肌细胞的AI无相关关系（P>0.05）。(3) 4组大鼠间的AI比较有显著差异（P<0.01）。两两比较各组AI，DCM组 > 糖尿病+缬沙坦预处理组、DCM+缬沙坦处理组 > 空白对照组。(4) 4组大鼠心肌组织3-NT表达指数比较有显著差异（P<0.01）；两两比较，DCM组显著大于其它3组。(5) 4组大鼠血中3-NT的浓度比较无显著差异（P>0.05）。结论：(1) DCM大鼠心肌组织中3-NT的表达显著增多并与心肌细胞凋亡密切相关，缬沙坦能够抑制DCM大鼠心肌细胞中3-NT的表达，并由此抑制DCM大鼠心肌细胞凋亡。(2) 循环血中的3-NT水平不能真实反映DCM大鼠心肌组织中3-NT表达水平及其对心肌细胞凋亡的影响。

Relationship between 3-nitrotyrosine and myocardial cell apoptosis in rat diabetic cardiomyopathy

AIM: To explore the relationship between 3-nitrotyrosine (3-NT) level in hearts or blood and myocardial cell apoptosis in rat diabetic cardiomyopathy (DCM). METHODS: Sixty Sprague-Dawley (SD) rats (male, 8-week-old) were randomly divided into 4 groups: normal group, diabetic cardiomyopathy group (DCM group), diabetic rats treated with valsartan (40 mg·kg^-1·d^-1, D+V group) and DCM rats treated with valsartan (40 mg·kg^-1·d^-1, DCM+V group). Apoptotic index (AI) of rat cardiac myocytes was examined by TUNEL. The expression index (EI) of 3-NT in rat cardiac myocytes was examined by immunohistochemistry. The 3-NT concentration in rat serum was examined by ELISA. RESULTS: (1) Significant differences of the heart weight indexes among the 4 groups were observed (P<0.01). The heart weight indexes in DCM group and DCM+V group were higher than those in normal group and D+V group (P<0.01). (2) The EI of 3-NT in the cardiac myocytes was positively correlated with the AI of the cardiac myocytes in the same group (P<0.01), but the concentration of 3-NT in blood had no correlation with the AI of cardiac myocytes (P>0.05). (3) The difference of AI of cardiac myocytes among the 4 groups had statistical significance (P<0.01). The arrangement from high to low of AI was DCM group > D+V group and DCM+V group > N group (P<0.05). (4) The EI of 3-NT in DCM group was the highest as compared to other groups (P<0.05). (5) No statistical difference of 3-NT concentration in blood among the 4 groups was observed (P>0.05). CONCLUSION: (1) The expression of 3-NT in DCM myocardial tissues in SD rats is significantly increased and closely correlated with the apoptosis in myocardial cells. Valsartan inhibits 3-NT expression in DCM myocardial cells, thus inhibits the DCM myocardium apoptosis. (2) The 3-NT level in blood can not be true for reflection of 3-NT expression in DCM myocardial tissues and its effect on myocardial cell apoptosis.