HF-rTMS improves swallowing function in rats with poststroke dysphagia by increasing nucleus tractus solitarius excitability through the NMDAR1-Npas4-Nav1.1 pathway.

Researchers investigated whether high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) could improve swallowing problems that often occur after stroke. Swallowing difficulties affect many stroke survivors and can lead to serious complications like aspiration pneumonia and malnutrition. The study used rats with stroke-induced swallowing problems to understand how brain stimulation affects the nucleus tractus solitarius (NTS), a critical brain region that controls swallowing reflexes. Scientists applied 10 Hz magnetic stimulation and measured swallowing function using video X-ray studies. They found that HF-rTMS significantly improved swallowing ability by increasing the excitability of neurons in the NTS through a specific molecular pathway involving NMDAR1, Npas4, and Nav1.1 proteins. The treatment increased excitatory signals in the brain while decreasing inhibitory ones, essentially "turning up" the brain's swallowing control center. When researchers blocked this pathway, the beneficial effects disappeared, confirming the mechanism. While this study was conducted in rats and not humans, it helps explain why brain stimulation therapies might help stroke patients recover swallowing function. For patients interested in non-invasive neurological recovery approaches, acupuncture shares similarities with magnetic stimulation in that both modulate neural excitability and may support stroke rehabilitation. Acupuncture has been studied for post-stroke dysphagia and may work through complementary mechanisms to enhance swallowing recovery. If you are considering acupuncture for stroke recovery or swallowing difficulties, seek treatment from a licensed acupuncturist with experience in neurological rehabilitation.

This study examined HF-rTMS (10 Hz) effects on nucleus tractus solitarius (NTS) excitability in rats with poststroke dysphagia induced by transient middle cerebral artery occlusion. Videofluoroscopy swallowing studies demonstrated significant improvement in swallowing function following HF-rTMS treatment. Mechanistic analysis revealed HF-rTMS increased CaMKIIα and VGLUT2 expression, enhanced mEPSC amplitude, upregulated NMDAR1, Npas4, and Nav1.1, while decreasing VGAT expression. Genetic and chemical inhibition experiments confirmed that blocking NTS excitability or Npas4 expression abolished therapeutic effects. The study identifies the NMDAR1-Npas4-Nav1.1 pathway as the mechanism by which HF-rTMS enhances NTS neuronal excitability. Clinical relevance: This research provides molecular evidence for neuromodulation approaches in dysphagia rehabilitation. While conducted in animal models, findings support the rationale for non-invasive brain stimulation therapies, including potentially electroacupuncture, which may similarly modulate central swallowing pathway excitability. Practitioners should consider multimodal approaches incorporating neuromodulation principles when treating post-stroke swallowing disorders.