Effects of the intrastriatal administration of selective dopaminergic agonists on Fos expression in the rat brain

In this study, we mapped the cerebral expression of Fos protein following intrastriatal stimulation of D(1) or D(2) receptors, in freely moving animals. Animals treated with the D(1) agonist SKF 38393 showed massive Fos increases in the cerebral cortex, ipsilaterally to the injected striatum, which were counteracted by systemic administration of D(1) antagonist SCH 23390. Conversely, D(2) agonist quinpirole suppressed cortical expression of Fos, while systemic administration of D(2) antagonist eticlopride relieved this blockade. As for the basal ganglia, Fos was consistently expressed only in the injected striatum of rats receiving SKF 38393. These results show that striatal dopamine receptors may play a role in the modulation of cortical activity. They also provide new information on a class of drugs--the dopamine agonists--whose role in the therapeutic strategy of Parkinson's disease is continuously evolving.