ADENOSINE-A2 STIMULATION OF TYROSINE-HYDROXYLASE IN RAT STRIATAL MINCES IS REVERSED BY DOPAMINE-D2 AUTORECEPTOR ACTIVATION

The adenosine agonist, 2-chloroadenosine, stimulated tyrosine hydroxylase activity in rat striatal minces; this effect was attenuated by activation of dopamine (DA) D2 autoreceptors with N-n-propylnorapomorphine and antagonized by theopylline. Forskolin and 8-bromo-cAMP also increased tyrosine hydroxylase activity and their effects were not altered by 2-chloroadenosine. D1, α, β and 5-HT agonists did not affect tyrosine hydroxylase activity. Evidently, A2 receptors on DA nerve terminals stimulate striatal DA synthesis and this effect is negatively modulated by D2 autoreceptors, probably via changes in intracellular cAMP levels. © 1990.