Effect of ultrasonic intensity on the Amyloid-β induced apoptosis of PC-12 cells

Previous studies have shown that the effect of Amyloid-β (Aβ) on the induction of apoptosis could lead neuronal loss to the Alzheimer's disease. The stimulation by physical energy, such as optics, was found able to greatly diminish Aβ induced apoptosis. This study is to further explore the effect of different ultrasonic energies on the neuronal cells. The experiments were carried out using such precursor neuronal cells as PC-12 which was added with Aβ of a 20 μM concentration during pre-cultured preparation. These cells were subsequently stimulated by a 20% duty cycle ultrasound of different energies ranged from 50 to 150 mW(SATA) for three minutes. The cellular response under ultrasound exposure was assessed, 7 times within 48 hours after those cells were stimulated, using the microscopic morphology, cell death measured by the typical MTT assay, and DNA fragmentation assay. Results showed that stimulations by ultrasound intensities of lower and higher than 100 mW/cm2 may respectively diminish and increase Aβ induced apoptosis compared to those control groups. Morphological results indicated that those cells stimulated by higher intensity ultrasounds tended to activate more differentiations in PC-12 discerned by morphological changes. This study demonstrated that the proliferation to diminish apoptosis and differentiation of neuronal cells could be regulated with the insonation of an appropriate ultrasonic intensity.