Autophagy, or cellular self-digestion, is an essential process for eliminating abnormal protein in mammalian cells. Accumulating evidence indicates that increased neuronal autophagy has a protective effect on neurodegenerative disorders. It has been reported that low-intensity pulsed ultrasound (LIPUS) can noninvasively modulate neural activity in the brain. Yet, the effect of LIPUS on neuronal autophagy is still unclear. The objective of this study was to examine whether LIPUS stimulation could induce neuronal autophagy. Primary neurons were treated by LIPUS with a frequency of 0.68 MHz, a pulse repetition frequency (PRF) of 500 Hz, a spatial peak temporal-average intensities ( ${I}_{\text {SPTA}}$ ) of 70 and 165 mW/cm ² . Then, the immunofluorescent analysis of LC3B was carried out for evaluating neuronal autophagy. Furthermore, 0.5-MHz LIPUS was noninvasively delivered to the cortex and hippocampus of adult mice ( ${n} = {16}$ ) with PRF of 500 Hz and ${I}_{\text {SPTA}}$ of 235 mW/cm ² . The LC3BII/LC3BI ratio and p62 (autophagic markers) were measured by western blot analysis. In the in vitro study, the expression of LC3B in primary neurons was statistically improved after LIPUS stimulation was implemented for 4 h ( ${p} < {0.01}$ ). With the increase in the irradiation duration or acoustic intensity of LIPUS stimulation, the expression of LC3B in primary neurons was increased. Furthermore, transcranial LIPUS stimulation increased the LC3BII/LC3BI ratio ( ${p} < {0.05}$ ) and decreased the expression of p62 ( ${p} < {0.05}$ ) in the cortex and hippocampus. We concluded that LIPUS provides a safe and capable tool for activating neuronal autophagy in vitro and in vivo .

中文翻译：

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经颅低强度脉冲超声刺激诱导神经元自噬

自噬或细胞自消化是消除哺乳动物细胞中异常蛋白质的重要​​过程。越来越多的证据表明，增加的神经元自噬对神经退行性疾病具有保护作用。据报道，低强度脉冲超声 (LIPUS) 可以无创地调节大脑中的神经活动。然而，LIPUS 对神经元自噬的影响仍不清楚。本研究的目的是检查 LIPUS 刺激是否可以诱导神经元自噬。LIPUS 处理初级神经元，频率为 0.68 MHz，脉冲重复频率 (PRF) 为 500 Hz，空间峰值时间平均强度（ ${I}_{\text {SPTA}}$ ) 70 和 165 mW/cm ² 。然后，进行 LC3B 的免疫荧光分析以评估神经元自噬。此外，0.5-MHz LIPUS 被非侵入性地传递到成年小鼠的皮层和海马。 ${n} = {16}$ ) 具有 500 Hz 的 PRF 和 ${I}_{\text {SPTA}}$ 235 mW/cm ² 。通过蛋白质印迹分析测量 LC3BII/LC3BI 比率和 p62（自噬标志物）。在里面体外 研究表明，LIPUS 刺激 4 h 后原代神经元中 LC3B 的表达有统计学改善。 ${p} < {0.01}$ ）。随着LIPUS刺激照射时间或声强度的增加，原代神经元中LC3B的表达增加。此外，经颅 LIPUS 刺激增加了 LC3BII/LC3BI 比率（ ${p} < {0.05}$ ) 并降低 p62 的表达 ( ${p} < {0.05}$ ) 在皮层和海马体中。我们得出结论，LIPUS 为激活神经元自噬提供了一种安全且有效的工具体外 和 体内 .