Multi-session transcranial direct current stimulation (tDCS) elicits inflammatory and regenerative processes in the...

Area of Science:

• Neuroscience
• Regenerative Medicine
• Neuroimmunology

Background:

• Stroke recovery research increasingly utilizes transcranial direct current stimulation (tDCS) as an adjuvant therapy.
• The precise neurobiological mechanisms underlying tDCS effects in vivo remain largely unelucidated.
• Previous in vitro studies suggest electric fields influence cell migration, but in vivo evidence is lacking.

Purpose of the Study:

• To investigate the in vivo effects of tDCS on cell recruitment in the rat brain.
• To determine if tDCS influences endogenous neural stem cell (NSC) populations and immune responses.
• To explore potential polarity-specific effects of tDCS on neurobiological processes.

Main Methods:

• Adult Wistar rats underwent anodal or cathodal tDCS for 5 or 10 days (500 µA, 15 min).
• Bromodeoxyuridine (BrdU) was administered to label dividing cells.
• Immunohistochemistry was used to analyze activated microglia (Iba1) and endogenous neural stem cells (NSC).

Main Results:

• Multi-session tDCS did not induce cortical lesions.
• Both anodal and cathodal tDCS elicited an innate immune response, indicated by upregulated Iba1-positive microglia.
• Cathodal tDCS significantly increased the number of proliferating endogenous NSC in the stimulated cortex by approximately 60% after 10 days.

Conclusions:

• tDCS, in both anodal and cathodal forms, induces a pro-inflammatory response characterized by microglial activation.
• Cathodal tDCS demonstrates a polarity-specific effect, promoting the migration and proliferation of endogenous neural stem cells in vivo.
• These findings suggest tDCS may activate NSC and modulate neuroinflammation in stroke patients, warranting further clinical investigation.