TRPC4/TRPC5 are critical for neuronal modulation by transcranial focused ultrasound in retrosplenial cortex in male mice

Abstract

Transcranial focused ultrasound (tFUS) enables non-invasive neuromodulation, yet its underlying molecular mechanisms remain largely elusive. Here, we show that transient receptor potential canonical 4 (TRPC4) and transient receptor potential canonical 5 (TRPC5) channels are critical mediators of tFUS-induced neuronal modulation in the mouse brain. Applying tFUS to the retrosplenial cortex (RSC) in male mice desensitizes mechanical and thermal sensitivity while robustly elicits early growth response 1 (Egr1) expression. Inhibiting these tFUS-induced Egr1 ensembles blocks the somatic sensory effects. Transcriptomic analysis identifies Trpc4 enrichment in tFUS-activated Egr1-positive cells. Both pharmacological inhibition and genetic knockdown of TRPC4 abolish tFUS-mediated sensory modulation. Targeted knockdown further demonstrates that the highly homologous TRPC5 plays a comparable role. In situ proximity ligation assay, co-immunoprecipitation, and live-cell calcium imaging confirm that TRPC4 and TRPC5 form a protein complex in the RSC that facilitates the tFUS response. These findings establish TRPC4/TRPC5 as essential molecular components for tFUS neuromodulation.

Abstract via europepmc.

Flags from extraction

• n_subjects — The paper reports dozens of separate group sizes across many distinct behavioural, electrophysiological, molecular and imaging experiments (e.g., n=5-13 mice per group in different assays) with no single stated total number of animals exposed to tFUS.
• n_sessions_per_subject — Number of tFUS sessions per animal varies by experiment (single acute sessions for most assays, repeated trains within a session for behavioural tests) and no single value is stated.
• sham_type — The mechanism of the 'Ctrl' condition (device present but inactive vs. no device) is not explicitly described; one control experiment used ultrasound stimulation of ACC while recording RSC (no-stimulation baseline vs stimulation-on), but the general behavioural 'Ctrl' groups are not defined.
• auditory_control — A congenital deafness mouse model (Cdh23 mutant) was used to rule out auditory confounds, closest fitting vocabulary term is 'deafened_subjects', though this is a genetic model rather than acute deafening.
• exposures[0].unspecified_domain.pressure_kpa — Paper states 'sound pressure 214 kPa' without specifying whether this is a free-field/water measurement or an in-situ/transcranial value; placed in unspecified_domain.
• exposures[1].fundamental_frequency_khz — ACC and M1 stimulation used the same head-mounted stimulator and consistent temporal parameters as RSC per the paper's statement, but frequency/pressure are not individually restated for ACC/M1; values carried over from the RSC/device description.
• exposures[2].fundamental_frequency_khz — As above for M1.
• exposures[0].timing.duty_cycle_pct — Only pulse duration (0.5 ms) and pulse repetition interval (1 ms) are stated; duty cycle would require dividing these and was left unreported per the no-arithmetic rule.
• anaesthesia — Mice were anaesthetised for surgical implantation of the stimulator pedestal/electrodes, but tFUS itself was delivered to awake, freely moving/behaving mice; classified as awake for the stimulation exposure.