Regional effects of MK-801 on dopamine and its metabolites studied by in vivo microdialysis.

The non-competitive N-methyl-D-aspartate receptor antagonist MK-801 was observed to have regionally specific effects on the extracellular concentration of dopamine and its metabolites. In rat anterior striatum, MK-801 transiently decreased extracellular dopamine, in spite of inducing intense circling behaviour which is generally associated with an increase in this neurotransmitter. In contrast, hippocampal extracellular dopamine was increased in a dose-related manner by MK-801. The possible significance of these data is discussed in relation to some of the known behavioural actions of MK-801.