The Journal of neuroscience : the official journal of the Society for Neuroscience
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D1 receptors located on striatonigral neurons and D2 receptors located, together with A2A receptors, on striatopallidal neurons are known to interact functionally. Using in situ hybridization, we examined the effects of D1 and D2 agonists and of an A2A antagonist on c-fos mRNA in identified striatal neurons and in globus pallidus. The full D1 agonist, SKF 82958 (1 mg/kg), induced a homogenous increase of c-fos mRNA in the striatum. ⋯ However, only the combination of D1 and D2 agonists modified the c-fos mRNA expression to a "patchy" distribution. Our data show that (1) c-fos expression can be activated through D1 and inhibited through A2A or D2 receptors in both striatal output pathways in normal rats, and (2) D2 receptor stimulation as well as A2A receptor blockade can interact with D1 receptor activation to potentiate c-fos expression in the striatum and the globus pallidus. The data also suggest that the topological alteration of c-fos expression after coadministration of D1 and D2 agonists involves D2 receptors located on interneurons or presynaptically on dopaminergic nerve terminals.