Effect of Myostatin Depletion on Weight Gain, Hyperglycemia, and Hepatic Steatosis during Five Months of High-Fat Feeding in Mice

University of California, Los Angeles, and Cedars-Sinai Medical Center, United States of America
PLoS ONE (Impact Factor: 3.23). 02/2011; 6(2):e17090. DOI: 10.1371/journal.pone.0017090
Source: PubMed

ABSTRACT The marked hypermuscularity in mice with constitutive myostatin deficiency reduces fat accumulation and hyperglycemia induced by high-fat feeding, but it is unclear whether the smaller increase in muscle mass caused by postdevelopmental loss of myostatin activity has beneficial metabolic effects during high-fat feeding. We therefore examined how postdevelopmental myostatin knockout influenced effects of high-fat feeding. Male mice with ubiquitous expression of tamoxifen-inducible Cre recombinase were fed tamoxifen for 2 weeks at 4 months of age. This depleted myostatin in mice with floxed myostatin genes, but not in control mice with normal myostatin genes. Some mice were fed a high-fat diet (60% of energy) for 22 weeks, starting 2 weeks after cessation of tamoxifen feeding. Myostatin depletion increased skeletal muscle mass ∼30%. Hypermuscular mice had ∼50% less weight gain than control mice over the first 8 weeks of high-fat feeding. During the subsequent 3 months of high-fat feeding, additional weight gain was similar in control and myostatin-deficient mice. After 5 months of high-fat feeding, the mass of epididymal and retroperitoneal fat pads was similar in control and myostatin-deficient mice even though myostatin depletion reduced the weight gain attributable to the high-fat diet (mean weight with high-fat diet minus mean weight with low-fat diet: 19.9 g in control mice, 14.1 g in myostatin-deficient mice). Myostatin depletion did not alter fasting blood glucose levels after 3 or 5 months of high-fat feeding, but reduced glucose levels measured 90 min after intraperitoneal glucose injection. Myostatin depletion also attenuated hepatic steatosis and accumulation of fat in muscle tissue. We conclude that blocking myostatin signaling after maturity can attenuate some of the adverse effects of a high-fat diet.

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Available from: Tianshun Xu, Jul 25, 2014
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    • "Myostatin knockout mice have a dramatic increase in muscle mass, a reduction in fat mass and a resistance to obesity caused by diet and genetic mutation (McPherron and Lee, 2002; Guo et al., 2009). Because muscle is a significant glucose consumer, it is not surprising that constitutive myostatin depletion by conditional genetic mutation (Wilkes et al., 2009; Burgess et al., 2011) and application of a myostatin receptor blocker (Akpan et al., 2009) can reduce weight gain and improve hyperglycemia, IR and hepatic steatosis caused by a high-fat diet in mice. Follistatin is known to be the most potent antagonist of myostatin (Lee and McPherron, 2001; Haidet et al., 2008) and has been reported as a candidate gene for women with PCOS (Urbanek et al., 1999). "
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    ABSTRACT: STUDY QUESTION: What is the role of myostatin and its relationship with obesity, androgens and follistatin levels in women with polycystic ovary syndrome (PCOS)? SUMMARY ANSWERS: The myostatin level was positively correlated to the risk of abdominal obesity, but negatively associated with circulating levels of dehydroepiandrosterone sulfate (DHEAS) and follistatin in women with PCOS. WHAT IS KNOWN AND WHAT THIS PAPER ADDS: Myostatin is a well-known negative regulator of skeletal muscle and is involved in metabolism; however, little is known about the role of myostatin in women with PCOS. In this study, we found that the myostatin level was positively related to the risk of abdominal obesity, but negatively related to the circulating levels of DHEAS and follistatin in women with PCOS. Such a relationship might imply a potential regulatory role of androgens and follistatin in the metabolism of skeletal muscle in women with PCOS. DESIGN: A cross-sectional case-control study. PARTICIPANTS AND SETTING: A total of 239 untreated, consecutive women with PCOS and 38 healthy volunteer women without PCOS were enrolled and studied in a tertiary medical center. MAIN RESULTS AND THE ROLE OF CHANCE: Myostatin level was higher in women with PCOS than those without PCOS (16.6±15.6 and 14.2±9.7, P=0.025), but were not significantly different between non-obese women with and without PCOS after considering the effect of obesity (P=0.09). Stepwise multivariate regression analysis in women revealed that only the presence of PCOS (β=0.256, P=0.0001), total testosterone (β=0.159, P=0.031), DHEAS (β=-0.188, P=0.0003) and follistatin (β=-0.171, P=0.0001) levels were left in the final model and were significantly related to the myostatin level after considering all the explanatory variables. By using stepwise multivariate regression analysis, the total testosterone levels (β=0.196, P=0.003) were positively, but the DHEAS (β=-0.196, P<0.0001) and follistatin (β=-0.151, P=0.0001) levels were negatively, related to myostatin levels in women with PCOS after adjustment for age, anthropometric measurements, insulin sensitivity index and hormonal profiles. The high myostatin level was associated with the increased risk of abdominal obesity after further adjusting the androgens and follistatin levels in women with PCOS. LIMITATION, REASONS FOR CAUTION: This study is a cross-sectional case-control design, and therefore, cannot answer the cause-effect relationship among the androgens, follistatin and myostatin levels. The small sample size and non-obese control group may also limit the application of the conclusion of the present study to general population other than women with PCOS. In addition, lack of data regarding muscle mass is another limitation in this study that prevents clarification of the relationship between myostatin, lean mass and obesity and therefore restricts the clinical application of the results. WIDER IMPLICATIONS OF THE FINDINGS: Future studies to investigate the efficacy of exercise and lifestyle modification in treating women with PCOS should consider the myostatin, follistatin and androgen levels as well as the effect of muscle mass and BMI. STUDY FUNDING/COMPETING INTEREST: This study was supported by grants NSC97-2314-B002-079-MY3, NSC98-2314-B002-105-MY3 and NSC 100-2314-B002-027-MY3 from the National Science Council of Taiwan. There is no competing interest declared in this study.
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