Mesencephalic dopamine innervation of the frontoparietal (sensorimotor) cortex of the rat: a microdialysis study

Results obtained in a study using an in vivo microdialysis technique show that dopamine is detected in perfusates collected from the frontoparietal (sensorimotor) cortex of control rats (dopamine = 0.7 +/- 0.2 nM, n = 10) or of rats with cortical lesions produced by the neurotoxin kainic acid (0.9 +/- 0.2 nM, n = 4). However, cortical dopamine levels were strongly reduced (0.07 +/- 0.06 nM, n = 4) following deafferentation induced by mesencephalic 6-hydroxydopamine injection. Dopamine levels, but not its metabolites could be increased by local KCl application, supporting the idea that extracellular dopamine collected by microdialysis reflects a pool of releasable neurotransmitter.