Exertional heart stroke causes long-term obesity and cardiac hypertrophy in mice

Abstract

Exertional heat stroke (EHS) is a life-threatening illness that can lead to short- and long-term adverse health outcomes. Several human epidemiology studies have shown that heat stroke exposure is highly associated with the development of cardiovascular disease later in life. However, whether EHS causes heart disease or individuals with predispositions to heart disease are more susceptible to EHS is unknown. Previously, our laboratory demonstrated metabolic abnormalities in the myocardium of mice, two weeks after EHS, characterized by lipid accumulation. In this study, we hypothesized that EHS exposure in mice leads to long-term susceptibilities to cardiovascular disease that is accelerated by co-exposure to a Western diet. METHODS: Sixty-four male (n=32) and female (n=32) C57BL/6 mice were exposed to either EHS (forced wheel running in 34.5°C for males and 37.5°C for females) or sham exercise controls (EXC, forced wheel running in ~22.5°C). Fourteen days later, mice were placed on either a Western diet (WD) or a standard diet (SD) and then followed for 9 additional weeks. At week 12, post interventions (EHS or EXC), animals were euthanized and samples collected for analysis. RESULTS: Male mice exposed to EHS with either WD ( P = 0.0001) or SD ( P = 0.0001) gained more body mass over the 9-week diet period compared to diet matched EXC controls. Also, regardless of diet, male mice exposed to EHS consumed more food compared to matched EXC (WD: P < 0.005 and SD: P < 0.04). However, only female mice exposed to EHS with WD gained more body mass compared to female EXC mice with WD ( P < 0.04). At the end of the study, and regardless of diet, male mice exposed to EHS showed enlarged hearts in terms of absolute mass (WD: P=0.0241, SD: P=0.0069) and relative mass/tibia length (WD: P=0.013, SD P=0.03). On the other hand, EHS female mice exposed to WD showed enlarged heart mass compared to EHS on SD ( P=0.0005). CONCLUSIONS: These results demonstrate that EHS exposure in mice leads to a long-term metabolic disorder characterized by greatly accelerated weight gain, greater appetite and cardiac hypertrophy. Effects were more evident and consistent in males. Such a response is typical of early stages of metabolic syndrome and would likely contribute to eventual cardiac disease. Therefore, the data is consistent with EHS exposure being a risk factor for long term heart disease. U.S. Army Grant BA180078 and from King Saud University, Saudi Arabia This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.