Abstract
Obesity is a complex metabolic disorder that often leads to a decrease in insulin sensitivity, chronic inflammation, and overall decline in human health and well‐being. In mouse skeletal muscle, obesity has been shown to impair muscle regeneration after injury; however, the mechanism underlying these changes has yet to be determined. To test whether there is a negative impact of obesity on satellite cell (SC) decisions and behaviors, we fed C57BL/6 mice normal chow (NC, control) or a high‐fat diet (HFD) for 10 weeks and performed SC proliferation and differentiation assays in vitro. SCs from HFD mice formed colonies with smaller size (p < .001) compared to those from NC mice, and this decreased proliferation was confirmed (p < .05) by BrdU incorporation. Moreover, in vitro assays showed that HFD SCs exhibited diminished (p < .001) fusion capacity compared to NC SCs. In single fiber explants, a higher ratio of SCs experienced apoptotic events (p < .001) in HFD mice compared to that of NC‐fed mice. In vivo lineage tracing using H2B‐GFP mice showed that SCs from HFD treatment also cycled faster (p < .001) than their NC counterparts. In spite of all these autonomous cellular effects, obesity as triggered by high‐fat feeding did not significantly impair muscle regeneration in vivo, as reflected by the comparable cross‐sectional area (p > .05) of the regenerating fibers in HFD and NC muscles, suggesting that other factors may mitigate the negative impact of obesity on SCs properties.
Highlights
Obesity is a metabolic disease characterized by an accumulation of adipose tissue in the body due to a positive energy balance in which energy intake is greater than energy expenditure (Serra, Mera, Malandrino, Mir, & Herrero, 2013)
Nuclear magnetic resonance (NMR) scans of the mice showed an increase in body fat mass in the high-fat diet (HFD) mice compared to the normal chow (NC) mice, but no differences were noted in skeletal muscle mass (Figure 1b)
Oil Red O staining for lipid accumulation revealed an increase in lipid accumulation in the skeletal muscle of HFD mice in comparison to NC mice (Figure 1c)
Summary
Obesity is a metabolic disease characterized by an accumulation of adipose tissue in the body due to a positive energy balance in which energy intake is greater than energy expenditure (Serra, Mera, Malandrino, Mir, & Herrero, 2013). Prevalence of obesity in the population has dramatically increased over the past several decades worldwide and has been linked to the occurrence of cardiovascular disease, Type 2 diabetes mellitus, renal dysfunction, asthma, sleep disorders, infertility, and others (Jung, 1997; Pi-Sunyer, 1991). Along with these pathologies, obesity is linked to an increased risk of metabolic syndrome, which is prominently defined in humans as the development of insulin resistance (Johnson, Milner, & Makowski, 2012). The underlying mechanisms causing an impairment in muscle repair are not fully understood, it has been suggested that muscle satellite cells could be impacted negatively by obesity
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