Low-intensity pulsed ultrasound suppresses proliferation and promotes apoptosis via p38 MAPK signaling in rat visceral preadipocytes

Low-intensity pulsed ultrasound (LIPUS) has been used widely in clinical therapy for bone fracture and soft tissue injury. However, whether LIPUS regulates primary preadipocyte function and adipogenesis remains unknown. In this study, we investigated the potential role of LIPUS in regulating visceral preadipocyte function. Resuspended rat visceral preadipocytes were treated with LIPUS (0.5 MHz, 109.44 mW/cm(2)) for 1 min and then cultured for an additional 48 hours. Cell proliferation was examined using the CCK-8 assay, and the early apoptosis rate was determined by flow cytometry. In addition, we evaluated the related signaling pathway via examination of proliferating cell nuclear antigen (PCNA), peroxisome proliferator-activated receptor gamma (PPAR.), Bcl2, Bax, cleaved caspase 3 (C-C3), and mitogen-activated protein kinase (MAPK) member protein levels using western blot or quantitative real-time PCR (qRT-PCR). LIPUS inhibited preadipocyte proliferation and induced cell apoptosis. The protein expression of proliferation markers decreased, while expression of the apoptosis-related modulators increased following LIPUS treatment. LIPUS treatment decreased extracellular signal-regulated kinase (ERK) phosphorylation and increased p38 MAPK phosphorylation. Inhibition of p38 MAPK rescued the LIPUS-induced proliferation inhibition and apoptosis induction. Thus, treatment of rat visceral preadipocytes with 0.5 MHz LIPUS suppresses proliferation and promotes apoptosis via activation of p38 MAPK signaling.