Cardiac Fibrosis Alleviated by Exercise Training Is AMPK-Dependent

Area of Science:

• Cardiology
• Exercise Physiology
• Molecular Biology

Background:

• Regular exercise offers cardioprotection, but the underlying molecular mechanisms remain unclear.
• Understanding how exercise protects the heart from stress is crucial for developing preventative strategies.

Purpose of the Study:

• To investigate the role of adenosine monophosphate-activated protein kinase (AMPK) in exercise-mediated cardiac protection.
• To determine if AMPK activation mediates protection against β-adrenergic receptor overstimulation.

Main Methods:

• Mice with and without the AMPKα2 gene were subjected to swimming training or sedentary conditions.
• Mice received isoproterenol (ISO) injections to induce cardiac stress.
• Cardiac fibrosis, AMPK activation, reactive oxygen species (ROS), NADPH oxidase, and antioxidant enzyme expression were analyzed.

Main Results:

• Swimming training reduced ISO-induced cardiac fibrosis in wild-type mice but not in AMPKα2-knockout mice.
• Exercise activated cardiac AMPK in wild-type mice.
• Training attenuated ISO-induced ROS production and NADPH oxidase expression while enhancing antioxidant enzymes, dependent on AMPKα2.

Conclusions:

• Swimming exercise attenuates isoproterenol-induced cardiac fibrosis via an AMPK-dependent inhibition of the NADPH oxidase-ROS pathway.
• AMPK activation is a key mechanism mediating the cardioprotective effects of exercise against β-adrenergic overstimulation.