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 recept or, has been shown to activate c-fos to a detectable level in rats onl y when the striatum has been sensitized by a previous 6-OHDA lesion of the nigrostriatal tract. In the present study, we reexamine the effec t 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 edg e and to the caudal part of the caudoputamen (CP) even with large dose s of SKF 38 393. These results suggest a functional heterogeneity in t he CP in response to dopaminergic drugs, which could reflect the anato mical or neurochemical heterogeneity of the striatum itself and its ne uroanatomical connections.