Abstract

Specific binding of the labeled dopamine analogue 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene to highly purified rat striatal synaptic membranes appears to be closely associated with binding sites for dopamine. The specific binding of the analogue is saturable, with an apparent dissociation constant of 1.2 µM, which correlates with the concentration required to produce half-maximal stimulation of the striatal dopamine-sensitive adenylate cyclase. Binding was enriched in the synaptic membrane fraction, and the regional distribution of binding correlated with the known distribution of dopamine and its receptors. Displacement of binding occurred in the presence of dopamine and the potent neuroleptic cis-flupenthixol. The possible nature of the receptor for 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene on synaptic membranes is discussed.