Compartmentally specific effects of quinpirole on the striatal Fos expression induced by stimulation of D-1-dopamine receptors in intact rats

Injections of the full D-1-agonist A-77636 (1.45 mg/kg) were found to induce clear Fos-like immunoreactivity (FLI) in the striatum of neurologically intact rats. Pretreatment with the D-2-like agonist quinpirole (3 mg/kg) potentiated staining in the lateral striatum, but actually decreased the number of immunoreactive cells observed in the medial portion of the rostral striatum. Comparison with adjacent sections processed for the calcium binding protein calbindin, indicated that quinpirole pretreatment specifically suppressed staining in the matrix compartment of the striatum while tending to potentiate it in the striosomes, resulting in an extremely patchy pattern of labeling. These results suggest that exogenous stimulation of D-2-receptors, although not essential for the induction of FLI, may play an important role in the compartmental patterning of neuronal activity within the striatum. (C) 1997 Elsevier Science B.V.