Functional and Histologic Changes After Repeated Transcranial Direct Current Stimulation in Rat Stroke Model

Abstract

Transcranial direct current stimulation (tDCS) is associated with enhancement or weakening of the NMDA receptor activity and change of the cortical blood flow. Therefore, repeated tDCS of the brain with cerebrovascular injury will induce the functional and histologic changes. Sixty-one Sprague-Dawley rats with cerebrovascular injury were used. Twenty rats died during the experimental course. The 41 rats that survived were allocated to the exercise group, the anodal stimulation group, the cathodal stimulation group, or the control group according to the initial motor function. Two-week treatment schedules started from 2 days postoperatively. Garcia, modified foot fault, and rota-rod performance scores were checked at 2, 9, and 16 days postoperatively. After the experiments, rats were sacrificed for the evaluation of histologic changes (changes of the white matter axon and infarct volume). The anodal stimulation and exercise groups showed improvement of Garcia's and modified foot fault scores at 16 days postoperatively. No significant change of the infarct volume happened after exercise and tDCS. Neuronal axons at the internal capsule of infarct hemispheres showed better preserved axons in the anodal stimulation group. From these results, repeated tDCS might have a neuroprotective effect on neuronal axons in rat stroke model.

Intensity-dependent effects of repetitive anodal transcranial direct current stimulation on learning and memory in a rat model of Alzheimer’s disease

“…Furthermore, similar results were 78 found and even maintained for at least 4 weeks after repetitive 79 anodal tDCS (Boggio et al, 2012). Beyond human, one study based 80 on AD rats suggested the application of anodal tDCS over the fron-81 tal cortex has beneficial effects on restoration of cognitive skill (Yu,82 Park, & Sim, 2014) which possibly resulted from the potential 83 neuron-protective effect (Kim et al, 2010) and the wide-spread 84 modulatory function in cortical-subcortical network of tDCS 85 (Fregni et al, 2006). 86 The stimulation parameters, such as polarity, stimulation time 87 and current intensity have diverse influences on the effects 88 induced by tDCS (Nitsche et al, 2008).…”

“…Based on previous findings, 89 it is commonly agreed that tDCS induced effects are modulated in a 90 polarity-specific manner ( (Benninger et al, 2010;Boggio et al, 2007). In rats, 103 repetitive rather than single tDCS has been proven to improve 104 motor function, and elicit inflammatory and regenerative pro-105 cesses in rat stroke models (Kim et al, 2010;Rueger et al, 2012). 106 Similar repetitive stimulations were found to have antiepileptic 107 effects in epilepticus rats (Kamida et al, 2011).…”

Effects of transcranial direct current stimulation on hemichannel pannexin-1 and neural plasticity in rat model of cerebral infarction

“…Similarly, Kim et al (2010) found that neuronal axons at the internal capsule of infarcted hemispheres were better preserved after anodal TDCS stimulation in the rat stroke model.…”

“…Rats received TDCS daily until sacrifice. The TDCS parameters were set as follows: frequency, 10 Hz; intensity, 0.1 mA (Kim et al, 2010). The active electrode was positioned 5 mm to the left and 2 mm in front of the interaural line.…”

“…Therefore, it only regulates the excitability of neurons in the active state, and will not cause spontaneous discharge of dormant neurons (Wagner et al, 2007). Additionally, TDCS is associated with augmentation or weakening of N-methyl-D-aspartate (NMDA) receptor activity (Kim et al, 2010). A clinical study observed that the NMDA receptor antagonist dextromethorphan can block the effects of anodal and cathodal TDCS on nerve cells (Liebetanz et al, 2002) and it was speculated that NMDA receptors are involved in TDCS-induced modulation of neural plasticity.…”