Abstract
Obesity increases the risk of developing diabetes and subsequently, diabetic cardiomyopathy (DMCM). Reduced cardioprotective antioxidant hydrogen sulfide (H2S) and increased inflammatory cell death via pyroptosis contribute to adverse cardiac remodeling and DMCM. Although exercise training (EX) has cardioprotective effects, it is unclear whether EX mitigates obesity-induced DMCM by increasing H₂S biosynthesis and mitigating pyroptosis in the heart. C57BL6 mice were fed a high-fat diet (HFD) while undergoing treadmill EX for 20 weeks. HFD mice developed obesity, hyperglycemia, and insulin resistance, which were reduced by EX. Left ventricle pressure-volume measurement revealed that obese mice developed reduced diastolic function with preserved ejection fraction, which was improved by EX. Cardiac dysfunction was accompanied by increased cardiac pyroptosis signaling, structural remodeling, and metabolic remodeling, indicated by accumulation of lipid droplets in the heart. Notably, EX increased cardiac H₂S concentration and expression of H₂S biosynthesis enzymes. HFD-induced obesity led to features of type 2 diabetes (T2DM), and subsequently DMCM. EX during the HFD regimen prevented the development of DMCM, possibly by promoting H₂S-mediated cardioprotection and alleviating pyroptosis. This is the first report of EX modulating H₂S and pyroptotic signaling in the heart.
Highlights
Obesity, primarily due to changes in diet to higher fat and higher sugar foods, independently increases the risk of developing heart failure [1]
This corresponded to the increased body fat percent in high-fat diet (HFD) mice when measured with Dual Energy X-ray Absorbance (DEXA) (Figure 1E,F)
After 18 weeks of HFD feeding, mice had an average body fat percentage of 32.7% ± 1.94% when compared to their normal diet (ND)-fed littermates, which had 18.5% ± 1.65% body fat
Summary
Primarily due to changes in diet to higher fat and higher sugar foods, independently increases the risk of developing heart failure [1]. Metabolic syndrome from obesity leads to type 2 diabetes (T2DM) that progresses to diastolic dysfunction and diabetic cardiomyopathy (DMCM) [2,3,4]. High-fat diet (HFD) models have produced inconclusive effects on cardiac dysfunction and remodeling, and the molecular mechanisms by which HFD leads to DMCM are not well established [5,6,7]. Human and rodent studies show that exercise training (EX) regimens improve cardiac function in metabolic syndrome and diabetes. EX was found to normalize diastolic function in HFD-fed obese and T2DM mice [10,11].
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