香草乙酮通过抑制CaMKⅡ活性保护压力负荷小鼠的心功能

Apocynin protects pressure overload induced cardiac dysfunction by inhibiting CaMKⅡ phosphorylation

目的:探讨香草乙酮(Apo)对压力负荷心衰小鼠心功能的保护作用以及机制。方法:48只C57BL/6雄性小鼠,随机分为sham、sham+Apo、TAC、TAC+Apo组,每组12只。采用主动脉缩窄术(TAC)构建压力负荷小鼠模型,术后3 d根据分组给予不同处理4周;利用小动物超声仪检测心功能各项指标的变化;苏木精-伊红(HE)染色和马松(Masson)染色观察各组小鼠心肌细胞横截面积(CSA)变化和心肌胶原容积分数(CVF);实时荧光定量PCR(qRT-PCR)检测心肌肥厚和心肌纤维化相关基因的变化;蛋白质印迹(Western Blot)法分析心肌组织中的钙/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKⅡ)及其磷酸化水平。结果:与sham组相比,TAC组小鼠的心功能下降,心肌细胞明显增大,纤维化程度增加,相关基因的mRNA水平明显上调,CaMKⅡ磷酸化水平显著升高。腹腔注射Apo后,能够改善压力负荷导致的心功能降低,CSA和CVF减小,相关基因的mRNA水平相对下降,CaMKⅡ磷酸化水平也明显下降。结论:Apo能够通过抑制CaMKⅡ活性和降低心室纤维化保护压力负荷心衰小鼠的心功能。

Objective: To investigate the effect of apocynin(Apo) on pressure overload induced cardiac dysfunction in mice and the underlying mechanism.Methods: Forty-eight C57 BL/6 male mice were randomly divided into four groups: sham, sham+Apo, TAC, and TAC+Apo. Mice models of pressure overload were constructed by transverse aortic constriction(TAC). Three days later, the mice were fed with Apo or saline for 4 weeks. A small animal ultrasound machine was used to detect the changes of cardiac function indexes. Hematoxylin-eosin staining and Masson staining were carried out to observe the cross-sectional area of myocardial cells(CSA) and collagen volume fraction(CVF), respectively. The real-time fluorescence quantitative PCR(qRT-PCR) was used to detect the mRNA levels of myocardial hypertrophy and myocardial fibrosis. Western Blot was used to analyze the level of calcium/calmodulin dependent protein kinase Ⅱ(CaMKⅡ) and its phosphorylation level.Results:Compared with those in sham group, the cardiac function was decreased in the TAC group, CSA,CVF, the mRNA levels of related genes, and CaMKⅡ phosphorylation levels were significantly increased in TAC group. After intraperitoneal injection of apocynin, the cardiac function impaired by pressure overload was improved, the CSA, CVF, the mRNA levels of related genes, and CaMKⅡphosphorylation levels were significantly decreased.Conclusion: Apo can protect pressure overload induced heart function deterioration by inhibiting CaMKⅡ activity and reducing ventricular fibrosis.