High-frequency rTMS inhibits astrocyte reactive activation and protects blood-brain barrier function after cerebral infarction via the miR-665/STAT3/MMP-9 axis.

Abstract

BACKGROUND AND OBJECTIVES: Astrocyte-associated blood-brain barrier (BBB) integrity is vital for recovery after ischemic stroke. High-frequency repetitive transcranial magnetic stimulation (rTMS) shows potential for neurological recovery, but its mechanisms remain unclear. This study investigates how high-frequency rTMS facilitates neurological recovery and mitigates BBB injury. METHODS: Male Sprague-Dawley rats subjected to transient middle cerebral artery occlusion (tMCAO) were treated with or without 10 Hz rTMS. Neurological recovery was assessed via mNSS and adhesive removal tests. BBB permeability, infarct volume, and astrocyte activation were measured. Brain-derived exosomes were analyzed through high-throughput sequencing. In vitro, an astrocyte oxygen-glucose deprivation/reperfusion (OGD/R) model was established. The miR-665/STAT3/MMP-9 signaling pathway was validated through gain- and loss-of-function experiments both in vivo and in vitro. RESULTS: High-frequency rTMS significantly improved neurological function, reduced infarct volume, and decreased BBB permeability. It inhibited reactive astrocyte activation and reduced MMP-9 expression. Mechanistically, rTMS upregulated miR-665 in brain-derived exosomes, which targeted and inhibited STAT3. Importantly, while STAT3 overexpression attenuated the protective effects of rTMS on BBB integrity and astrocyte inhibition, miR-665 overexpression partially reversed the antagonistic effects of STAT3 overexpression on rTMS, restoring its therapeutic benefits. CONCLUSION: High-frequency rTMS promotes neurological recovery by modulating the miR-665/STAT3/MMP-9 signaling pathway, thereby inhibiting neurotoxic astrocyte activation and preserving BBB integrity. These findings provide novel insights into the mechanisms of rTMS and identify potential therapeutic targets for post-stroke BBB injury.