Oxidative stress-dependent impairment of cardiac-specific transcription factors in experimental diabetes

Area of Science:

• Cardiology
• Endocrinology
• Molecular Biology

Background:

• Diabetic cardiomyopathy involves myocyte loss and fibrosis, leading to heart failure.
• Oxidative stress is a key factor in diabetic cardiomyopathy development.
• Dehydroepiandrosterone (DHEA) production is reduced in failing hearts and may protect against oxidative damage.

Purpose of the Study:

• To investigate how oxidative stress causes reduced myocardial contractility in diabetic rats.
• To examine the effects of dehydroepiandrosterone (DHEA) on diabetic cardiomyopathy.
• To analyze downstream signaling pathways affected by hyperglycemia and DHEA treatment.

Main Methods:

• Administered oral dehydroepiandrosterone (DHEA) to streptozotocin (STZ)-induced diabetic and genetic diabetic-fatty (ZDF) rats.
• Assessed oxidative balance, advanced glycated end products (AGEs), AGE receptors, cardiac myogenic factors, and myosin heavy-chain (MHC) gene expression in left ventricles.
• Analyzed the role of nuclear factor-kappaB (NF-κB) signaling pathway.

Main Results:

• Hyperglycemia-induced oxidative stress increased AGEs and AGE receptors, activating nuclear factor-kappaB (NF-κB).
• NF-κB activation led to a shift in cardiac myosin heavy-chain (MHC) gene expression from alpha-MHC to beta-MHC isoforms.
• Dehydroepiandrosterone (DHEA) treatment prevented NF-κB activation, normalized AGE receptor signaling, and preserved cardiac myogenic factors and MHC gene expression.

Conclusions:

• Dehydroepiandrosterone (DHEA) effectively counteracts oxidative stress and prevents early molecular events in diabetic cardiomyopathy.
• DHEA normalizes downstream signaling pathways, including NF-κB activation and MHC gene expression changes.
• DHEA represents a potential therapeutic agent for managing diabetic cardiomyopathy and preventing heart failure in diabetic patients.