Contralesional cTBS promotes motor function by enhancing synaptic plasticity and axonal remodeling via TGF-β/Smad3/Foxp3 signaling axis in ischemic stroke rats.

Intracortical microstimulation (ICMS), an emerging therapeutic neuromodulation strategy, has shown promise in improving stroke recovery. However, the mechanisms of ICMS in promoting neurological restoration remain elusive. We assessed motor dysfunction in middle cerebral artery occlusion/reperfusion (MCAO/R) rats following 3-week contralesional intermittent versus continuous theta-burst stimulation (iTBS vs. cTBS) in the subacute phase. Subsequently, we evaluated cTBS efficacy with or without TGF-β1 inhibitor (SB431542). We investigated structural and molecular alterations via RNA sequencing, magnetic resonance imaging, in-vivo electrophysiology, anterograde viral tract tracing, and histological methods. Contralesional cTBS significantly ameliorated MCAO/R-induced motor and structural deficits, which may depend on the TGF-β signaling and myelination pathways as confirmed by RNA sequencing. cTBS significantly increased the expressions of proteins such as MBP, PSD-95, SYN, pro-BDNF in the peri-infarct region and enhanced axonal fiber density as assessed by confocal images. Further results revealed that cTBS effectively shifted the neuro-inflammatory balance by elevating IL-10 and restraining pro-inflammatory IL-17 in the peri-infarct cortex via activating the TGF-β/Smad3/Foxp3 axis. TGF-β1 inhibition (SB431542) significantly reversed the behavioral and synaptic plasticity improvements following cTBS treatment. Contralesional cTBS could promote motor recovery by enhancing neuroplasticity and axonal remodeling via the TGF-β/Smad3/Foxp3 pathway.