Vardenafil Alleviates Doxorubicin-Induced Cardiotoxicity Associated with Restoration of the AMPK/SIRT1 Signaling Pathway

Background: Doxorubicin-induced cardiotoxicity (DIC) is a major limitation of anthracycline chemotherapy and is characterized by oxidative stress, apoptosis, and myocardial remodeling. Dysregulation of AMP-activated protein kinase (AMPK) and its downstream effector sirtuin-1 (SIRT1) has been implicated in the molecular pathogenesis of DIC. Vardenafil (Var), a selective phosphodiesterase-5 inhibitor, has shown cardiovascular benefits; however, its impact on AMPK/SIRT1 signaling during DIC remains unclear. Methods: DIC was induced in rats by cumulative doxorubicin administration. Cardiac function, serum injury biomarkers, oxidative stress indices, histopathological alterations, apoptosis, fibrosis, and molecular markers associated with the AMPK/SIRT1 pathway were evaluated. In addition, molecular docking was performed to assess the potential interaction of Var with AMPK. Results: Var significantly improved cardiac function and reduced serum levels of lactate dehydrogenase, creatine kinase, and blood urea nitrogen. Treatment attenuated myocardial oxidative stress, restored glutathione content, reduced lipid peroxidation, and alleviated histopathological damage. Furthermore, Var suppressed caspase-3 and TGF-β1 expression while enhancing HO-1 levels. Var treatment was associated with restoration of cardiac phosphorylated AMPK (p-AMPK) expression and increased SIRT1, Nrf2, and PPARγ levels in doxorubicin-treated rats, consistent with modulation of an AMPK/SIRT1-associated cytoprotective network. Molecular docking demonstrated favorable interactions between Var and AMPK, providing supportive in silico evidence for the observed molecular findings. Conclusions: These findings demonstrate that Var attenuates doxorubicin-induced cardiotoxicity, and its cardioprotective effects are associated with restoration of the p-AMPK/SIRT1/Nrf2/PPARγ signaling pathway, together with reductions in oxidative stress, apoptosis, and fibrosis. Collectively, these findings suggest that Var attenuates early Dox-induced cardiac injury, potentially through modulation of the AMPK/SIRT1 signaling pathway, warranting further validation in long-term and dose–response studies.