Glycyrrhiza uralensis attenuates TNF-α-induced muscle atrophy in myoblast cells through the Nrf2 and MAFbx signaling cascades

Muscle atrophy is associated with chronic diseases, such as heart failure diabetes, and aging-related diseases. Glycyrrhiza uralensis (GU) extract is widely used in traditional medicine. However, no studies have evaluated the effects of GU on muscle atrophy. Thus, in this study, we assessed the effects of GU on prevention of muscle atrophy. GU reduced the levels of the TNF-α-induced muscle atrophy markers, muscle RING-finger protein-1(Murf-1) and muscle atrophy F-box (MAFbx), and upregulated myosin heavy chain expression (MyHC). It also reduced the phosphorylation of nuclear factor kappa B, and downregulated Smad3 proteins, which are involved in protein ubiquitination. When we examined whether GU exhibits antioxidant activities. GU suppressed TNF-α-induced muscle atrophy by increasing the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of antioxidant factors such as heme oxygenase-1 (HO-1) as well as apoptosis-related factors, such as caspase-3/7. These results suggest that GU extract is potentially an important agent in the regulation of TNF-an induced muscle atrophy.