Effects of Transcranial Direct Current Stimulation on Motor and Cognitive Dysfunction in an Experimental Traumatic Brain Injury Model.

Aim: To investigate the therapeutic and neuroprotective effects of transcranial direct current stimulation (tDCS) application on the traumatic brain injury (TBI)-induced glutamate and calcium excitotoxicity and loss of motor and cognitive functions.

Material and methods: Forty rats were equally divided in the sham, TBI, tDCS + TBI + tDCS, and TBI + tDCS groups. Mild TBI was induced by dropping a 450-g iron weight from a height of 1 m onto the skull of the rats. The tDCS + TBI + tDCS group was prophylactically administered 1 mA stimulation for 30 min for 7 days starting 5 days before inducing TBI. In the TBI + tDCS group, tDCS (1 mA for 30 min) was administered 2 h after TBI, on days 1 and 2. Cognitive and locomotor functions were assessed using the novel object recognition and open field tests. The calcium, glutamate, and N-methyl-D-aspartate receptor 1 (NMDAR1) levels in the hippocampus were measured using enzyme-linked immunosorbent assay.

Results: Although the motor and cognitive functions were substantially reduced in the TBI group when compared with the sham, they improved in the treatment groups (p < 0.05). The calcium, glutamate, and NMDAR1 levels were considerably higher in the TBI group than in the sham (p < 0.001). However, they were considerably lower in the tDCS + TBI + tDCS and TBI + tDCS groups than in the TBI groups (p < 0.05). In particular, the change in the tDCS + TBI + tDCS group was higher than that in the TBI + tDCS group.

Conclusion: Application of tDCS before the development of TBI improved motor and cognitive dysfunction. It demonstrated a neuroprotective and therapeutic effect by reducing the excitotoxicity via the regulation of calcium and glutamate levels.