Guava leaf extract attenuated muscle proteolysis in dexamethasone induced muscle atrophic mice via ubiquitin proteasome system, mTOR-autophagy, and apoptosis pathway

Muscle atrophy is the waste or loss of muscle mass. Muscle atrophy is caused by physical inactivity, aging, or diseases such as diabetes, cancer, and heart failure. The number of patients suffering from musculoskeletal disorders is expected to increase in the future. However, intervention for muscle atrophy is limited, so research to treatment for muscle wasting is needed. This study hypothesized that guava leaf (Psidium guajava L., GL) would have ameliorative effects on muscle atrophy by regulation of protein degradation pathways in dexamethasone (DEX)-indued muscle atrophy mice model. Muscle atrophy was induced by DEX injection for 28 days in 7 weeks old male ICR mice. Then, low dose (LGL, 200 mg/kg) or high dose (HGL, 500 mg/kg) of GL extract (GLE) was supplemented by oral gavage for 21 days. Muscle strength, calf thickness, and body composition were analyzed. Histopathological changes in gastrocnemius muscle were examined using hematoxylin and eosin staining, and molecular pathways related to muscle degradation were analyzed by western blots. GLE treatment regardless of dose increased muscle strength in mice with muscle atrophy accompanied by attenuating autophagy related pathway in the DEX-induced muscle atrophy mice. Moreover, high dose of GLE treatment ameliorated ubiquitin proteasome system and apoptosis in the DEX-induced muscle atrophy mice. This study suggested that GLE could be helpful to improve muscle health and alleviate proteolysis by regulation of UPS, autophagy, and apoptosis, which are involved in muscle degradation. In conclusion, GLE would be a potential nutraceutical to prevent muscle atrophy.