Transcranial Ultrasound Stimulation Suppresses Neuroinflammation in a Chronic Mouse Model of Parkinson's Disease

Hui Zhou, Long Meng, Xiangxiang Xia, Zhengrong Lin, Wei Zhou, Na Pang, Tianyuan Bian, Tifei Yuan, Lili Niu, Hairong Zheng

IEEE Transactions on Biomedical Engineering 2021, 68, 3375-3387 · 10.1109/tbme.2021.3071807

rodentparkinsons diseasebehaviourhistology molecular

Abstract

Objective Neuroinflammation contributes to the development and progression of Parkinson's disease (PD). The aim of this study was to examine whether ultrasound (US) stimulation of the subthalamic nucleus (STN) could suppress the neuroinflammation in a chronic PD mouse model induced by 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). Methods A chronic PD mouse model was built by injections of 20mg/kg MPTP and 250 mg/kg probenecid at 3.5-day intervals for 5 weeks. Mice were randomized into control+sham, MPTP+sham and MPTP+STN+US group. For MPTP+STN+US group, ultrasound wave (3.8 MHz, 50% duty cycle, 1 kHz pulse repetition frequency, 30 min/day) was delivered to the STN the day after MPTP and probenecid injection (the early stage of PD progression). The rotarod test and pole test were performed to evaluate the behavioral changes after ultrasound treatment. Then, the activity of microglia and astrocyte were measured to evaluate the inflammation level in the brain. Results Ultrasound stimulation improved the latency to falls in the rotarod test (p = 0.033) and decreased the climbing time in the pole test (p = 0.016) compared with MPTP+sham group. Moreover, ultrasound stimulation reduced the chronic inflammation response as shown in microglia (p = 0.007) and astrocyte (p = 0.032) activation. In addition, HE, Nissl and Tunel staining showed that no brain tissue injury was induced by US. Conclusion These findings demonstrated that ultrasound stimulation could suppress neuroinflammation in PD mice. Significance Transcranial ultrasound neuromodulation offers a novel approach for Parkinson's disease intervention, potentially through its anti-neuroinflammation functions.

Abstract via europepmc.

Speciesmouse (C57BL/6J)

Subjects13, 11, 4, 4, 4swept animals

Sessions per subjectnot reported

Randomisedyes

Blindingdouble

Sham / controlinactive transducer, active control site

Auditory controlcontrol experiment

Readout timingoffline

Anaesthesiaawake

Readoutsbehaviour, histology molecular — Rotarod test; pole test; TH/Iba-1/GFAP immunohistochemistry; c-Fos immunohistochemistry; Western blot (TNF-alpha, IL-1beta, COX-2, NF-kB, alpha-synuclein, iNOS, SOD-1, SOD-2); HE, Nissl and TUNEL staining

Direction of effectexcitatoryUltrasound stimulation of the STN significantly increased c-Fos-positive neuron counts (neuronal activation) and improved motor performance (pole test, rotarod), rescued dopaminergic neuron loss, and reduced neuroinflammatory markers (TNF-alpha, IL-1beta, COX-2, NF-kB, Iba-1, GFAP, alpha-synuclein, iNOS) in chronic MPTP mice; ultrasound of V1 (active control site) did not improve motor function.

Adverse eventsnone observedHE, Nissl and TUNEL staining showed no hemorrhaging, tissue damage, or cell apoptosis in the sonicated regions; negative acoustic pressure (190 kPa) was far below the cavitation threshold (40 MPa) and MI (0.17) and Ispta (430 mW/cm2) were far below FDA limits for clinical ultrasound imaging (1.9 MI, 720 mW/cm2 Ispta).

Exposures

Exposure 1: Ultrasound stimulation of subthalamic nucleus (STN) in chronic MPTP mouse model

Target: subthalamic nucleus — “subthalamic nucleus (STN)”
Device: custom-built

Pulse timing
Waveform	pulsed
Fundamental frequency (kHz)	3,800	✓✓✓
Pulse duration (ms)	0.5	✓✓✓
Pulse repetition frequency (Hz)	1,000	✓✓✓
Duty cycle (%)	50pulse duration × PRF gives 50%	✓✓✓
Sonication duration (s)	1	✓✓✓

Pressure and intensity, by domain
Free-field pressure (kPa)	190	✓✓✓
Free-field Isppa (W/cm²)	not reported
Free-field Ispta (W/cm²)	0.43	✓✓✓
In-situ estimate	not reported
In-situ pressure (kPa)	not reported
In-situ Isppa (W/cm²)	not reported
In-situ Ispta (W/cm²)	not reported

Protocol, in the paper’s words

Ultrasound wave (3.8 MHz, 50% duty cycle, 1 kHz PRF, 30 min/day) was delivered to the STN of freely-moving mice via a wearable transducer, beginning the day after MPTP and probenecid injection (early stage of chronic PD progression); control+sham and MPTP+sham mice wore the transducer with the power turned off, and a separate MPTP+V1+US group received the same ultrasound parameters delivered to the primary visual cortex (V1) as an active control site to test for auditory/off-target confounds.

Flags from extraction

n_subjects — Sum of independent STN-ultrasound-exposed cohorts described in the paper: main behavioral/PD cohort (MPTP+STN+US, n=13), naive c-Fos characterization cohort (STN+US, n=4), and safety histology cohort (n=4); these are separate sub-experiments rather than a single reported total.
n_sessions_per_subject — Text states US was delivered 'the day after MPTP and probenecid injection', which recurred every 3.5 days over 5 weeks, but the total number of stimulation sessions per mouse is not explicitly stated.
sham_type — MPTP+V1+US group received real active ultrasound to a different (non-STN) target (V1) as an active control site, in addition to a power-off inactive-transducer sham (control+sham, MPTP+sham).
auditory_control — Authors used active ultrasound stimulation of a non-STN site (V1) to argue against an auditory-mediated confound, rather than a masking-sound or other listed auditory-control method.
exposures[0].device.manufacturer — Transducer was custom-fabricated in-house (PZT-8 ceramic, housing 3D-printed); no overall device manufacturer/model is given beyond the piezoelectric ceramic material source (Siansonic).