Aims: Adiponectin (APN) has been reported to protect against ischaemia-reperfusion injury and hypertrophy. However, few reports have investigated the cardioprotective effects of APN in doxorubicin (DOX)-induced cardiomyopathy; therefore, we studied the cardioprotective mechanisms of APN in this model.
Methods and results: In an in vivo study, we quantified the cardiac pathohistology of C57BL/6 mice [wild-type (WT) mice], APN transgenic mice with high APN concentrations [APN transgenic sense (SE) mice], and those with reduced APN concentrations [APN transgenic antisense (AS) mice] after intraperitoneal injections of DOX (4 mg/kg) weekly for 6 weeks. The survival rate after 14 days was significantly increased in APN-SE mice (WT vs. APN-AS vs. APN-SE: 40 vs. 17 vs. 73%, P < 0.05). We assessed myocardial pathohistological changes and observed that fibrosis and apoptosis were significantly decreased in APN-SE mice compared with those of the other groups. We also assessed DOX-induced apoptotic mechanisms in vitro using cultured cardiomyocytes isolated from neonatal WT mice. The expression of adenosine monophosphate-activated protein kinase (AMPK) and anti-apoptotic factor Bcl-2 increased, but that of pro-apoptotic factor Bax decreased in cardiomyocytes treated with highly concentrated APN. The protective effects of APN were reversed by the addition of an AMPK inhibitor (dorsomorphin) to the culture medium.
Conclusion: These data suggest that APN improved cardiac function through anti-apoptotic effects by up-regulation of AMPK in DOX-induced cardiomyopathy in mice.