Lespedeza bicolor extract supplementation reduced hyperglycemia-induced skeletal muscle damage by regulation of AMPK/SIRT/PGC1α–related energy metabolism in type 2 diabetic mice

Lespedeza bicolor (LB) is known to have antidiabetic activities; however, the underlying molecular mechanisms of LB in hyperglycemia-induced skeletal muscle damage is unclear. Inflammation and oxidative stress caused by type 2 diabetes mellitus (T2DM) not only contributes to insulin resistance, but also promotes muscle atrophy via decreased muscle protein synthesis and increased protein degradation, leading to frailty and sarcopenia. In this study, we hypothesized that LB extract (LBE) supplementatin has an ameliorative effect on hyperglycemia-induced skeletal muscle damage by activation of 5' adenosine monophosphate-activated protein kinase (AMPK)/sirtuin (SIRT)/proliferator-activated receptor γ coactivator 1α (PGC1α)-associated energy metabolism in mice with T2DM. Diabetes was induced by a high-fat diet with a 2-time streptozotoxin injection (30 mg/kg body weight) in male C57BL/6J mice. After diabetes was induced (fasting blood glucose level ≥140 mg/dL), the mice were administered with LBE at a low dose (100 mg/kg/d) or high dose (250 mg/kg/d) by gavage for 12 weeks. LBE supplementation ameliorated glucose tolerance and hemoglobin A1c (%) in mice with T2DM. Moreover, LBE supplementation upregulated protein levels of insulin receptor subunit-1 and Akt accompanied by increased translocation of glucose transporter 4 in mice with T2DM. Furthermore, LBE increased mitochondrial biogenesis by activating SIRT1, SIRT3, SIRT4, and peroxisome PGC1α in diabetic skeletal muscle. Meanwhile, LBE supplementation reduced oxidative stress and inflammation in mice with T2DM. Taken together, the current study suggested that LBE could be a potential therapeutic to prevent skeletal muscle damage by regulation AMPK/SIRT/PGC1α-related energy metabolism in T2DM.