Opposing actions of D1- and D2-dopamine receptors on arachidonic acid release and cyclic AMP production in striatal neurons.

D1- and D2-dopamine receptors exert important physiological actions on striatal neurons, but the intracellular second messenger pathways activated by these receptors are still incompletely understood. Using primary cultures of rat striatal cells, we have examined the effects of activating D1 or D2 receptors on arachidonic acid (AA) release and cyclic AMP accumulation. In striatal neurons labeled by incubation with [3H]AA, D2-receptor stimulation enhanced release of [3H]AA produced by application of the Ca2+ ionophore A23187 or of the purinergic agonist ATP. By contrast, D1-receptor stimulation inhibited [3H]AA release. This inhibitory effect of D1 receptors was accompanied by stimulation of adenylyl cyclase activity, measured as accumulation of cyclic AMP, and was mimicked by application of the adenylyl cyclase activator forskolin. The results indicate the existence of a novel signaling pathway for D2 and D1 receptors in striatum, potentiation and inhibition, respectively, of Ca(2+)-evoked AA release.