REGIONAL DIFFERENCES IN THE DOPAMINERGIC REGULATION OF CYCLIC-AMP FORMATION WITHIN THE RAT NUCLEUS-ACCUMBENS - COMPARISON WITH THE STRIATAL COMPLEX OF THE LIZARD GEKKO-GECKO

Effects of dopamine D2 receptor activation on the forskolin or D1 receptor stimulated formation of cyclic adenosine monophosphate (cyclic AMP) were investigated in tissue slices of two subregions of the rat nucleus accumbens and in the striatal complex of a lizard. Cyclic AMP production in the tissue was estimated by measuring the conversion of [H-3]adenine in a superfusion system. Activation of a D2 receptor appeared to inhibit the D1 receptor agonists or forskolin stimulated formation of cAMP in the rostrolateral, but not in the caudomedial part of the rat nucleus accumbens. In the striatal complex of the lizard the formation of cAMP was dramatically stimulated by forskolin, but only marginally by dopamine. Neither the forskolin, nor the dopamine stimulated cyclic AMP formation could be inhibited by activation of D2 receptors. These findings are compatible with previously obtained functional data indicating that especially the caudomedial part of the rat nucleus accumbens has much in common with the striatal complex of the lizard.