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The mechanosensitive ion channel Piezo1 contributes to ultrasound neuromodulation.

Authors: Zhu J, Xian Q, Hou X, Wong KF, Zhu T, Chen Z, He D, Kala S, Murugappan S, Jing J, Wu Y, Zhao X, Li D, Guo J, Qiu Z, Sun L

Transcranial low-intensity ultrasound is a promising neuromodulation modality, with the advantages of noninvasiveness, deep penetration, and high spatiotemporal accuracy. However, the underlying biological mechanism of ultrasonic neuromodulation remains unclear, hindering the development of efficacious treatments. Here, the well-known Piezo1 was studied through a conditional knockout mouse model as a major mediator for ultrasound neuromodulation ex vivo and in vivo. We showed that Piezo1 knockout (P1KO) in the right motor cortex of mice significantly reduced ultrasound-induced neuronal calcium responses, limb movement, and muscle electromyogram (EMG) responses. We also detected higher Piezo1 expression in the central amygdala (CEA), which was found to be more sensitive to ultrasound stimulation than the cortex was. Knocking out the Piezo1 in CEA neurons showed a significant reduction of response under ultrasound stimulation, while knocking out astrocytic Piezo1 showed no-obvious changes in neuronal responses. Additionally, we excluded an auditory confound by monitoring auditory cortical activation and using smooth waveform ultrasound with randomized parameters to stimulate P1KO ipsilateral and contralateral regions of the same brain and recording evoked movement in the corresponding limb. Thus, we demonstrate that Piezo1 is functionally expressed in different brain regions and that it is an important mediator of ultrasound neuromodulation in the brain, laying the ground for further mechanistic studies of ultrasound.

Introduction

Purpose Transcranial ultrasound stimulation
Study Objective Determine whether the mechanosensitive ion channel Piezo1 mediates ultrasound-induced neuromodulation in the brain using conditional Piezo1 knockout mice.
Animal model / Human subject Mouse (Mus musculus), strains: C57BL/6J and Piezo1 tm2.1Apat (conditional knockout), age 4–8 weeks, male
MRI or image guidance method not reported
Targeted brain region(s) Motor Cortex
Target coordinates Right motor cortex injections (mm): AP 0.0, ML -1.0, DV -1; AP +0.5, ML -1.0, DV -1; AP +0.5, ML -1.5, DV -1. Central amygdala (CEA) injections (mm): AP -1.22, ML -2.9, DV -4.60.
Cargo name and characteristics AAV
Route of administration intracranial

Outcomes and Safety

Summary of Outcomes Neuronal Piezo1 knockout significantly reduced ultrasound-induced calcium responses, limb movement, and EMG signals, identifying Piezo1 as a key mediator of transcranial ultrasound neuromodulation.
Duration of biological effect 300 ms
Safety-related matter The authors describe transcranial low-intensity ultrasound as noninvasive with "excellent safety" and report no adverse effects; they monitored auditory cortex activation and used smoothed waveforms to exclude auditory confounds, finding no obvious auditory activation differences between groups. No safety issues or adverse events were reported in the study.

Brain Region

Ultrasound Parameters

Ultrasound instrument not reported
FUS Frequency 0.5 MHz
FUS Intensity not reported
FUS Pressure 0.35 MPa
FUS Mode pulsed
Pulse duration 0.5 ms
Duration of a single FUS session not reported
Treatment frequency multiple sessions

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