Functional heterogeneity of the caudate-putamen as revealed by c-fos induction in response to D1 receptor activation.

SKF 38,393, a dopamine receptor agonist which stimulates the D1 receptor, has been shown to activate c-fos to a detectable level in rats only when the striatum has been sensitized by a previous 6-OHDA lesion of the nigrostriatal tract. In the present study, we reexamine the effect of SKF 38,393 by in situ hybridization in non-lesioned mice and show an induction of c-fos mRNA which is restricted to the ventricular edge and to the caudal part of the caudoputamen (CP) even with large doses of SKF 38,393. These results suggest a functional heterogeneity in the CP in response to dopaminergic drugs, which could reflect the anatomical or neurochemical heterogeneity of the striatum itself and its neuroanatomical connections.