High-Intensity Focused Ultrasound Decreases Subcutaneous Fat Tissue Thickness by Increasing Apoptosis and Autophagy

High-intensity focused ultrasound (HIFU) leads to decreased subcutaneous adipose tissue (SAT) thickness via heat-induced adipocyte necrosis. Heat can induce adipocyte apoptosis and autophagy, and it is known that nuclear or mitochondrial p53 is involved in apoptosis and autophagy. However, whether HIFU leads to apoptosis or autophagy is unclear. We evaluated whether HIFU decreases SAT thickness via p53-related apoptosis or autophagy in high-fat diet (HFD)-fed animals. The expression of nuclear and mitochondrial p53 was increased by HIFU. HIFU also led to decreased expression of BCL2/BCL-xL (an antiapoptotic signal), increased expression of BAX/BAK (an apoptotic signal), increased levels of cleaved caspase 3/9, and increased numbers of apoptotic cells as evaluated by TUNEL assay. Furthermore, HIFU led to increased levels of ATG5, BECN1, and LC3II/LC3I, and decreased levels of p62, a marker of increased autophagy. The thickness of SAT was decreased by HIFU. In conclusion, HIFU led to nuclear and mitochondrial p53 expression, which led to apoptosis and autophagy, and eventually decreased SAT thickness in HFD-fed animals.