Harnessing theta-gamma coupled brainwaves using ultrasound for spinal astrocyte revitalization and sustained neuropathic pain relief in mice

Abstract

Ultrasound stimulation is a promising non-invasive strategy for neuropathic pain, yet its sustained effects and underlying mechanisms remain poorly understood. We investigated brainwave-patterned low-intensity continuous theta-burst ultrasound stimulation (LI-cTBUS) in a mouse model of partial sciatic nerve crush injury (PCI). LI-cTBUS substantially alleviated mechanical allodynia during and after treatment. Mechanistically, PCI upregulated brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling, while LI-cTBUS enhanced extracellular BDNF uptake by spinal astrocytes, thereby normalizing the BDNF/TrkB pathway and restoring potassium chloride cotransporter 2 (KCC2) function. Furthermore, LI-cTBUS attenuated reactive astrogliosis via activation of the transient receptor potential ankyrin 1 (TRPA1) channel, indicating a glial mechanism for ultrasound-induced analgesia. Transcriptomic profiling revealed that PCI altered the spinal transcriptome, whereas LI-cTBUS reversed inflammatory signatures, corrected aberrant BDNF/TrkB signaling, and restored GABAergic transmission. Collectively, these findings demonstrate that LI-cTBUS reprograms reactive astrocytes, suppresses nociceptive signaling, and provides sustained relief from neuropathic pain, underscoring its therapeutic potential for non-invasive spinal neuromodulation.

Abstract via europepmc.

Flags from extraction

• exposures[0].timing.waveform — USCS is a nested burst pattern (5 pulses at 500 Hz forming a burst, bursts repeated at 40 Hz) mimicking clinical burst spinal cord stimulation; it is not a simple continuous/pulsed/theta pattern, so mapped to other_patterned. cTBUS-100/200Hz are explicitly named theta-burst by the authors.
• exposures[0].timing.pulse_repetition_frequency_hz — Nested burst structure: value taken as the within-burst pulse rate (500 Hz for USCS, 100 or 200 Hz for cTBUS-100/200), not the outer train/theta repetition rate (40 Hz for USCS, 5 Hz theta for cTBUS); an alternative reading could treat the outer rate as the PRF.
• exposures[0].timing.duty_cycle_pct — Not explicitly stated by the authors for any of the three in vivo patterns; could be computed from pulse duration and PRF but that arithmetic is avoided per instructions.
• exposures[0].timing.sonication_duration_s — 40 s total train duration is stated explicitly elsewhere for LI-cTBUS (single-pulse vs LI-cTBUS 40 s calcium-imaging comparison) and is consistent with 800 pulses / 4 pulses-per-burst at a 5 Hz train; the USCS protocol's total train duration is not explicitly stated and is not included in this value.
• exposures[0].unspecified_domain.isppa_w_cm2 — 0.77 W/cm2 is the default/baseline intensity for most in vivo experiments; 0.88, 3.4 and 10.8 W/cm2 are from the cTBUS-200Hz intensity screen; 77 W/cm2 is the high-intensity (HI-cTBUS) comparison condition used for the c-Fos immunohistochemistry experiment, not for the main behavioural dataset.
• exposures[1].timing.pulse_duration_ms — In vitro cTBUS-200Hz protocol is stated to reuse the same burst pattern as in vivo, but the paper does not explicitly restate the 3 ms pulse duration for the in vitro experiments, so left not_reported rather than assumed.
• n_subjects — Study comprises many small sub-experiments (N=3-13 mice each, both PCI and SNI models, plus in vitro cultures); no single total number of animals used across the whole study is stated.
• sham_type — No device-off or inactive-transducer sham is described for the main behavioural experiments; comparator groups are untreated PCI/SNI mice or sham-operated (surgical sham) controls rather than an ultrasound sham.