Verstärkung des antinozizeptiven Effekts der kathodalen transkraniellen Gleichstromstimulation durch den Dopaminagonisten Pergolid

Abstract

Transcranial direct current stimulation (tDCS) was recently reintroduced as a tool for inducing relatively long-lasting changes of cortical excitability in focal brain regions. Anodal stimulation over the motor cortex enhances cortical excitability while cathodal decreases it. Cathodal stimulation diminishes experimentally induced pain sensation and in parallel reduces the N2, P2 amplitudes of laser-evoked potentials (LEPs) immediately after the end of stimulation. Furthermore, it is known that the enhancement of D2 receptor activity by pergolide consolidates tDCS-generated excitability diminution up until the morning post stimulation. In the present study we investigated the effect of pergolide and cathodal tDCS over the motor cortex on acute pain perception induced with a Tm:YAG laser in a double-blind, randomized, placebo-controlled study. Subjective pain rating scores and amplitude changes of the N2 and P2 components of LEPs of 10 healthy subjects were analyzed prior to and following 15 minutes cathodal tDCS in five different time points. Our results demonstrate that cathodal tDCS significantly lowered the pain sensation for up to two hours. In accordance with the psychophysical results, the amplitude of N2 and N2-P2 components were reduced significantly. In addition to this, pergolide prolonged the effect of the cathodal tDCS for up to 24 hours. Our study highlights the antinociceptive effect of cathodal tDCS over the motor cortex and underscores the importance of the dopaminergic system for human neuroplasticity. Furthermore, the data suggests a first pharmacological add-on mechanism to prolong the excitability-diminishing effect of cathodal tDCS on pain perception for up to 24 hours post stimulation.