DOPAMINE-RECEPTOR GENE-EXPRESSION IN THE HUMAN MEDIAL TEMPORAL-LOBE

The distributions of the messenger RNA molecules encoding the five kno wn dopamine receptors have been determined in the medial temporal lobe of postmortem human brain. All five receptor mRNAs are present in tem poral lobe structures, although their distributions are heterogeneous. The D-1-like receptors, D-1 and D-5, have strikingly dissimilar distr ibutions. D-1 receptor mRNA is abundant in temporal neocortex but is r are elsewhere. D-5 receptor message, however, is seen in the hippocamp us, subicular complex, and in temporal cortex. The D-2-like receptors have similar distributions: D-2, D-3, and Dq receptor mRNAs are all id entifiable in the hippocampal formation and in the cortical regions of the medial temporal lobe. Distinct patterns of relative regional conc entrations for each message are observed, however, suggesting a neuroa natomical substrate for potential differences in dopaminergic regulati on within discrete regions of the medial temporal lobe. These results provide a description of the distribution of these receptor mRNAs in n ormal humans and suggest multiple levels of complexity as well as regu lation of the medial temporal lobe dopamine projection.