Abdominal LIPUS ameliorates simulated microgravity induced skeletal muscle atrophy via the gut-muscle axis

Study investigated if abdominal low-intensity pulsed ultrasound (LIPUS) alleviates simulated microgravity (hindlimb unloading, HU)-induced skeletal muscle atrophy by restoring gut microbiota. Mice were divided into control (NC), HU, and HU with daily abdominal LIPUS (HU + LIPUS) groups. Fecal microbiota transplantation (FMT) from LIPUS-treated mice to HU mice was also performed. After 28 days, abdominal LIPUS partially reversed HU-induced gut dysbiosis, restored intestinal barrier integrity, and increased short-chain fatty acid (SCFAs) levels. LIPUS downregulated muscle atrophy genes (MSTN, ActRIIB) and upregulated growth genes (Akt, mTOR) in HU mice, preventing muscle loss. SCFAs levels positively correlated with muscle function. HU mice receiving FMT from LIPUS-treated donors showed similar gut and muscle improvements as direct LIPUS treatment. Results demonstrate abdominal LIPUS ameliorates muscle atrophy by modulating the gut-muscle axis, offering a potential non-invasive strategy for astronauts and patients.