Effect of low-intensity ultrasound on mortality of PC12 induced by amyloid β_25-35

The aim of this study is to investigate the potential of using ultrasound (US) to protect neuronal cells from damage by amyloid beta (Aβ) peptide. Experiments were performed using PC12 cells with the addition of 20 μM Aβ_25-35, US stimulation, or both. 1-MHz US at a 20 % duty cycle with various intensities (10, 50, 10, and 150 mW/cm²) for 3 min was employed. The responses of PC12 cells were determined in terms of the survival rate via the MTT assay, cell morphology via optical microscopy, and cell apoptosis/necrosis characteristics via Annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) fluorescence staining and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end-labeling assay. The results show that the survival rate of PC12 cells in the presence of Aβ_23-35 increased by 4.8-6 % when the cells were exposed to 100- and 150-mW/cm² US. With US intensity of 150 mW/cm², the growth of neurites from PC12 cells was observed. The experiment results of cell stains with Annexin V-FITC/PI show that US decreased PC12 cell apoptosis and necrosis. In addition, for the PC12 cells with added Aβ_25-35, the fold change in cell apoptosis decreased by 0.36 when a US intensity of 150 mW/cm² was applied. In conclusion, lowintensity US decreases PC12 cell mortality caused by Aβ_23-35.