Diastolic Dysfunction in Alzheimer's Disease Model Mice is Associated with Aβ-amyloid Aggregate Formation and Mitochondrial Dysfunction

Alzheimer's Disease (AD) is a progressive neurodegenerative disease caused by the deposition of Aβ aggregates or neurofibrillary tangles. AD patients are primarily diagnosed with the concurrent development of several cardiovascular dysfunctions. While few studies have indicated the presence of intramyocardial Aβ aggregates, none of the studies have performed detailed analyses for pathomechanism of cardiac dysfunction in AD patients. This manuscript used aged APP/PS1 Tg and littermate age-matched wildtype (Wt) mice to characterize cardiac dysfunction and analyze associated pathophysiology. Detailed assessment of cardiac functional parameters demonstrated the development of diastolic dysfunction in APP/PS1 Tg hearts compared to Wt hearts. Muscle function evaluation showed functional impairment (decreased exercise tolerance and muscle strength) in APP/PS1 Tg mice. Biochemical and histochemical analysis revealed Aβ aggregate accumulation in APP/PS1 Tg mice myocardium. APP/PS1 Tg mice hearts also demonstrated histopathological remodeling (increased collagen deposition and myocyte cross-sectional area). Additionally, APP/PS1 Tg hearts showed altered mitochondrial dynamics, reduced antioxidant protein levels, and impaired mitochondrial proteostasis compared to Wt mice. APP/PS1 Tg hearts also developed mitochondrial dysfunction with decreased OXPHOS and PDH protein complex expressions, altered ETC complex dynamics, decreased complex activities, and reduced mitochondrial respiration. Our results indicated that Aβ aggregates in APP/PS1 Tg hearts are associated with defects in mitochondrial respiration and complex activities, which may collectively lead to cardiac diastolic dysfunction and myocardial pathological remodeling.