Medial Forebrain Bundle Stimulation or D‐2 Dopamine Receptor Activation Increases Preproenkephalin mRNA in Rat Striatum

Abstract

Electrical stimulation of the medial forebrain bundle, in a manner that augmented the release of dopamine in the forebrain, rapidly increased the striatal content of preproenkephalin (but not preprotachykinin) mRNA. This effect was mimicked by administration of either the indirect (dopamine-releasing) agonist methamphetamine or by the D-2 dopamine receptor agonist quinpirole, but not by the D-1 agonist SKF 38393. These data suggest that D-2 receptors, which mediate a stimulatory effect on enkephalin gene expression, may be subsaturated under basal conditions and, therefore, responsive to increases in synaptic dopamine.