Faeces tea of cherry caterpillar (larvae of Phalera flavescens) promotes differentiation into myotubes, activates mitochondria, and suppresses the protein expression of ubiquitin ligase in C2C12

Sarcopenia is a syndrome characterised by progressive and systemic loss of skeletal muscle mass and strength. In order to prevent sarcopenia and lead a healthy life, it is necessary to maintain muscle mass and prevent loss of muscle mass. Insect faeces have long been consumed as tea in China, both as a medicine and as a functional food. In the present work, we investigated the efficacy of cherry caterpillar faeces tea (PT) for treating sarcopenia, particularly concerning muscle building and atrophy suppression using C2C12 cells. PT treatment (0.2 mg/mL) increased myotube widths by approximately 40%, and increased the expression levels of Myod, Myog, and MYHC. Additionally, PGC1α, TFAM, SDHA, BCAT, and BCKDH were upregulated in a PT concentration-dependent manner. For PGC1α, which is the transcription coactivator, the protein expression level also increased in a concentration-dependent manner. The findings demonstrated that PT could stimulate PGC1α and activate mitochondria via branched-chain amino acid metabolism and the electron transport chain in C2C12 myoblasts. Furthermore, PT suppressed LPS-induce expression of IL6 and TNFα, and reduced the protein expression levels of the ubiquitin ligases Atrogin-1 and MuRF, which are major cause of muscle atrophy. These results indicated that PT could be effective for muscle building and suppression of atrophy.