Modulatory Effects of Dopamine D(2) Receptors on Spreading Depression in Rat Somatosensory Neocortex

INTRODUCTION: Spreading depression (SD) is a propagating wave of depolarization followed by depression of the neuroglial activities and can modulate extracellular dopamine concentrations in the neocortex. It has been shown that the dopaminergic system plays a role in migraine. SD has been suggested as a critical phenomenon in the pathophysiology of migraine. The aim of this study was to investigate the effect of dopamine D(2) receptors on the characteristic features of SD in rat neocortical tissues. METHODS: The effect of dopamine D(2) receptor agonist quinpirole and D(2) receptor antagonist sulpiride was tested on different characteristic features (amplitude, duration and velocity) of KCl-induced SD in somatosensory neocortical slices of adult rats. The effect of above-mentioned substances on production of long-term potentiation (LTP) in the neocortex was also evaluated. RESULTS: The present data revealed a dose-dependent suppression of the amplitude and duration of SD in the presence of the dopamine D(2) receptor antagonist sulpiride in the neocortex. D(2) dopamine receptor agonist quinpirole dose-dependently enhanced the amplitude and duration of the neocortical SD. Furthermore, application of D(2) receptor antagonist significantly suppressed induction of LTP. DISCUSSION: These results indicate that D(2) receptors modulate the initiation of SD in the neocortex. This finding refers to the potential role of D(2) receptor antagonist in treatment of migraine pain.