Transcranial focused ultrasound pulsation suppresses pentylenetetrazol induced epilepsy in vivo
Sin-Guang Chen, Chih-Hung Tsai, Chia-Jung Lin, Cheng-Chia Lee, Hsiang-Yu Yu, Tsung-Hsun Hsieh, Hao-Li Liu
Brain Stimulation 2020, 13, 35-46 · 10.1016/j.brs.2019.09.011
Abstract
Background Epilepsy is a neurological disorder characterized by abnormal neuron discharge, and one-third of epilepsy patients suffer from drug-resistant epilepsy (DRE). The current management for DRE includes epileptogenic lesion resection, disconnection, and neuromodulation. Neuromodulation is achieved through invasive electrical stimulus including deep brain stimulation, vagus nerve stimulation, or responsive neurostimulation (RNS). As an alternative therapy, transcranial focused ultrasound (FUS) can transcranially and non-invasively modulate neuron activity. Objective This study seeks to verify the use of FUS pulsations to suppress spikes in an acute epileptic small-animal model, and to investigate possible biological mechanisms by which FUS pulsations interfere with epileptic neuronal activity. Methods The study used a total of 76 Sprague-Dawley rats. For the epilepsy model, rats were administered pentylenetetrazol (PTZ) to induce acute epileptic-like abnormal neuron discharges, followed by FUS exposure. Various ultrasound parameters were set to test the epilepsy-suppressing effect, while concurrently monitoring and analyzing electroencephalogram (EEG) signals. Animal behavior was monitored and histological examinations were conducted to evaluate the hazard posed by ultrasound exposure and the expression of neuronal activity markers. Western blotting was used to evaluate the correlation between FUS-induced epileptic suppression and the PI3K-mTOR signaling pathway. Results We observed that FUS pulsations effectively suppressed epileptic activity and observed EEG spectrum oscillations; the spike-suppressing effect depended on the selection of ultrasound parameters and highly correlated with FUS exposure level. Expression level changes of c-Fos and GAD65 were confirmed in the cortex and hippocampus, indicating that FUS pulsations deactivated excitatory cells and activated GABAergic terminals. No tissue damage, inflammatory response, or behavioral abnormalities were observed in rats treated with FUS under these exposure parameters. We also found that the FUS pulsations down-regulated the S6 phosphorylation and decreased pAKT expression. Conclusion Our results suggest that pulsed FUS exposure effectively suppresses epileptic spikes in an acute epilepsy animal model, and finds that ultrasound pulsation interferes with neuronal activity and affects the PTZ-induced PI3K-Akt-mTOR pathway, which might help explain the mechanism underlying ultrasound-related epileptic spike control.
Abstract via europepmc.
Exposures
Exposure 1: FUS parametric sweep (acoustic levels 1-5) along cortex-hippocampus-thalamus trajectory in PTZ-induced epilepsy
Target: cerebral cortex, hippocampus, thalamus — “cortex, hippocampus and thalamus (FUS beam trajectory)”
Device: Sonic Concepts · SonicConcept ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 8, 30swept | ✓✓✓ |
| Sonication duration (s) | 100, 600swept | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | 0, 530swept | ✓✓✓ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | 0.703, 0.75, 1.25, 2.81swept | ✓✓✓ |
Six acoustic exposure levels (Table 1) combined MI 0-0.75, duty cycle 8% or 30%, and total exposure time 100 or 600 s at a fixed PRF of 100 Hz; level 0 (PTZ only, no FUS) served as control. FUS was delivered during a 30-min EEG recording session following intraperitoneal PTZ injection (100 mg/kg); a separate cohort received 3 repeated FUS sessions (days 0, 2, 4) for rotarod/behavioural safety testing.
Flags from extraction
n_subjects— 56 is the sum of animals in FUS-exposed acoustic levels 1-5 from Table 1 (excluding the 20 acoustic-level-0 PTZ-only controls); the paper does not give this total directly as one number.exposures[0].unspecified_domain.pressure_kpa— The paper's own phrase 'free-field measured pressure level after considering 10% transcranial pressure loss' mixes free-field and transcranially-corrected wording, so the domain (free_field vs in_situ) is ambiguous; placed in unspecified_domain.exposures[0].target.terms— The paper describes the FUS beam trajectory as passing through cortex, hippocampus and thalamus rather than naming one specific focal target nucleus.sham_type— The acoustic-level-0 PTZ-only control group's ultrasound-apparatus procedure (if any, e.g. mock positioning) is not described.n_sessions_per_subject— The EEG/spike-suppression cohort received a single FUS session, while a separate cohort for rotarod safety testing received FUS on days 0, 2 and 4 (3 sessions); no single per-subject count applies to the whole study.