Transcranial direct-current stimulation increases extracellular dopamine levels in the rat striatum

Tomoko Tanaka,Kazuto Kobayashi,Yuji Takano,Takashi Hanakawa,Satoshi Tanaka,Manabu Honda,Naoyuki Hironaka,Katsumi Watanabe

doi:10.3389/fnsys.2013.00006

Abstract

Background: Transcranial direct-current stimulation (tDCS) is a non-invasive procedure that achieves polarity-dependent modulation of neuronal membrane potentials. It has recently been used as a functional intervention technique for the treatment of psychiatric and neurological diseases; however, its neuronal mechanisms have not been fully investigated in vivo.Objective/Hypothesis: To investigate whether the application of cathodal or anodal tDCS affects extracellular dopamine and serotonin levels in the rat striatum.Methods: Stimulation and in vivo microdialysis were carried out under urethane anesthesia, and microdialysis probes were slowly inserted into the striatum. After the collection of baseline fractions in the rat striatum, cathodal or anodal tDCS was applied continuously for 10 min with a current intensity of 800 μA from an electrode placed on the skin of the scalp. Dialysis samples were collected every 10 min until at least 400 min after the onset of stimulation.Results: Following the application of cathodal, but not anodal, tDCS for 10 min, extracellular dopamine levels increased for more than 400 min in the striatum. There were no significant changes in extracellular serotonin levels.Conclusion: These findings suggest that tDCS has a direct and/or indirect effect on the dopaminergic system in the rat basal ganglia.

Highlights

Transcranial direct-current stimulation is a non-invasive technique in which a weak DC is used to polarize target brain regions (Nitsche and Paulus, 2000)
These findings suggest that Transcranial direct-current stimulation (tDCS) has a direct and/or indirect effect on the dopaminergic system in the rat basal ganglia
To examine whether cathodal or anodal tDCS affected extracellular dopamine and serotonin levels in the striatum, we investigated the effect of tDCS using in vivo microdialysis

Summary

Introduction

Transcranial direct-current stimulation (tDCS) is a non-invasive technique in which a weak DC is used to polarize target brain regions (Nitsche and Paulus, 2000). Several studies have previously shown that tDCS affects motor function and learning in healthy subjects, presumably by changing the neuronal activity of the stimulated site (Wassermann and Grafman, 2005; Tanaka et al, 2009; Bachmann et al, 2010; Fox, 2011; Schambra et al, 2011) It is effective in patients with psychiatric and neurological diseases, and so has the potential to be used as an adjuvant strategy in the rehabilitation of motor and cognitive deficits caused by neurological disorders (Hummel et al, 2005; Boggio et al, 2006; Fregni et al, 2006; Lefaucheur, 2009; Murphy et al, 2009; Nitsche et al, 2009; Benninger et al, 2010; Tanaka et al, 2011a; Brunoni et al, 2012). Transcranial direct-current stimulation (tDCS) is a non-invasive procedure that achieves polarity-dependent modulation of neuronal membrane potentials It has recently been used as a functional intervention technique for the treatment of psychiatric and neurological diseases; its neuronal mechanisms have not been fully investigated in vivo

Methods

Results

Conclusion