M100,907, a selective 5-HT2A antagonist, attenuates dopamine release in the rat medial prefrontal cortex

Hewlet McFarlane, Kenyon College


Previous research has suggested that serotonin 5-HT2A receptors modulate the functioning of themesocortical dopamine (DA) pathway. However, the specific role of 5-HT2A receptors localized within themedial prefrontal cortex (mPFC) is not known. The present study employed in vivo microdialysis to examine the role of this receptor in the modulation of basal and K+-stimulated (Ca2+-dependent) DA release. The selective 5-HT2A antagonist M100,907 was infused directly into the mPFC of conscious rats. This resulted in a concentration-dependent blockade of K+-stimulated DA release. Intracortical application of M100,907 also blocked increases in DA release produced by the systemic administration of the 5-HT2A/2C agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). These findings demonstrate that local 5-HT2A antagonism has an inhibitory effect on stimulated, Ca2+-dependent DA release. They suggest that cortical 5-HT2Areceptors potentiate the phasic release of mesocortical DA.