Magnetic stimulation induces neuronal c-fos via tetrodotoxin-sensitive sodium channels in organotypic cortex brain slices of the rat.

Repetitive transcranial magnetic stimulation is a novel non-invasive method with antidepressant properties, where electromagnetic fields are applied via an electrode. The aim of the present study was to investigate in an in vitro model if magnetic stimulation may activate the transcription factor c-fos. Organotypic brain slices of the parietal cortex were cultured for 2 weeks and then treated with a magnetic stimulator. Immunohistochemistry was used to detect c-fos like immunoreactivity. We show that magnetic stimulation (1 Hz, 10 min, 75% machine output/magstim 200 rapid stimulator) transiently enhanced c-fos 3-6 h after stimulation. Co-localization experiments revealed that c-fos was expressed in neurons but not astroglia. The activation of c-fos by magnetic stimulation was inhibited by the sodium-channel blocker tetrodotoxin (TTX) (10 microM). It is concluded that magnetic stimulation induces neuronal c-fos via TTX-sensitive sodium channels in organotypic cortex slices.