Apocynin attenuates oxidative stress and cardiac fibrosis in angiotensin Ⅱ-induced cardiac diastolic dysfunction in mice

摘要

Aim:To investigate whether apocynin,a NADPH oxidase inhibitor,produced cardioproteictive effects in Ang Ⅱ-induced hypertensive mice,and to elucidate the underlying mechanisms.Methods:C57BL/6 mice were subcutaneously infused Ang Ⅱ for 4 weeks to mimic cardiac remodeling and fibrosis.Concomitantly the mice were administered apocynin (100 mg· kg-1·d-1) or/and the aldosterone receptor blocker eplerenone (200 mg·kg-1d-1) via gavage for 4 weeks.Systolic blood pressure (SBP) and heart rate were measured,and transthoracic echocardiography was performed.For in vitro study,cardiac fibroblasts were treated with Ang Ⅱ (10 7 mol/L) in the presence of apocynin (105 mol/L) or/and eplerenone (105 mol/L).Immunohistochemistry and Western blotting were used to quantify the expression levels of NADPH oxidase and osteopontin (OPN) proteins in the cells.Results:Both apocynin and eplerenone significantly decreased SBP,and markedly improved diastolic dysfunction in Ang Ⅱ-induced hypertensive mice,accompanied with ameliorated oxidative stress and cardiac fibrosis.In the Ang Ⅱ-treated cardiac fibroblasts,the expression levels of NOX4 and OPN proteins were markedly upregulated.Both Apocynin and eplerenone significantly suppressed the increased expression levels of NOX4 and OPN proteins in the Ang Ⅱ-treated cells.In all the experiments,apocynin and eplerenone produced comparable effects.Co-administration of the two agents did not produce synergic effects.Conclusion:Apocynin produces cardioproteictive effects comparable to those of eplerenone.The beneficial effects of apocynin on myocardial oxidative stress and cardiac fibrosis might be mediated partly through a pathway involving NADPH oxidase and OPN.