Pharmacological characterization of D₁ and D₂ dopamine receptors in rat limbocortical areas. II. Dorsal hippocampus

The mesolimbocortical dopamine (DA) system innervates several brain regions including the hippocampus. The aim of the present study was both to identify and to pharmacologically characterize the DA receptors located in this brain area. The results show that different agonists for D₁ DA receptors, such as DA itself, SKF 82526 and (-)-apomorphine, were able to increase adenylate cyclase activity, and these effects were antagonized by haloperidol and SCH 23390. Moreover bromocriptine, lisuride and RU 24213, which are agonists for D₂ DA receptors, inhibited the cyclic AMP generating system and these effects were prevented by (-)-sulpiride. According to the paradigm that D₁ DA receptors are linked with adenylate cyclase in a stimulatory way, while D₂ DA receptors are linked with the same enzyme in an inhibitory way, our results indicate the presence of both D₁ and D₂ receptors in rat hippocampus. Localization studies show that both DA receptor subtypes are restricted to the dorsal part of the hippocampus.