DISTRIBUTION OF MESSENGER-RNAS FOR D-1 DOPAMINE-RECEPTORS AND DARPP-32 IN STRIATUM AND CEREBRAL-CORTEX OF THE CYNOMOLGUS MONKEY - RELATIONSHIP TO D-1 DOPAMINE-RECEPTORS

Messenger RNAs for the D-1 dopamine receptor and dopamine- and cyclic AMP-regulated phosphoprotein of relative mass 32,000 (DARPP-32) were examined by in situ hybridization in the cynomolgus monkey brain. The messenger RNA distribution was compared to the distribution of D-1 dopamine receptors using [H-3]SCH 23390 autoradiography. In the caudate nucleus and putamen, D-1 dopamine receptor messenger RNA-positive cells were unevenly distributed. Clusters of cells with an approximately three-fold higher intensity of labeling, as compared to surrounding regions, were found. Some of these D-1 dopamine receptor messenger RNA intensive cell clusters in the caudate nucleus appeared to some extent to be matched to regions of higher intensity of [H-3]SCH 23390 binding. The distribution of cells expressing DARPP-32 messenger RNA in the caudate nucleus and putamen was found to be non-clustered. In neocortical regions, cells of different sizes expressing D-1 dopamine receptor messenger RNA were present in layers II-VI. D-1 dopamine receptor messenger RNA-positive cells were most abundant in layer V. Unexpectedly, no DARPP-32 messenger RNA signal was detected in neocortex. Chronic SCH 23390 administration did not change the relative levels of messenger RNAs for the D-1 dopamine receptor and DARPP-32 or [H-3]SCH 23390 binding as measured by quantitative image analysis. The clustered distribution of D-1 dopamine receptor messenger RNA is in contrast to that of DARPP-32 messenger RNA. This suggests that D-1 dopamine receptors may play a more significant role in regulating DARPP-32 function in patch regions as compared to matrix regions. D-1 dopamine receptor messenger RNA-expressing cells could also be visualized in several layers of the primate neocortex, implying that dopamine acts through D-1 dopamine receptors within functionally different neuronal circuits of the neocortex.