THE SUBCELLULAR-DISTRIBUTION OF H-3! CGS-21680 BINDING-SITES IN THE RAT STRIATUM - COPURIFICATION WITH CHOLINERGIC NERVE-TERMINALS

The subcellular distribution of the adenosine A2a receptor in rat stri atum has been investigated using specific binding of the A2a-selective ligand H-3!-CGS 21680. After subcellular fractionation, the distribu tion of H-3!-CGS 21680 binding was similar to that of the cholinergic nerve terminal marker acetylcholinesterase rather than the more gener al membrane marker 5'-nucleotidase, with 42% of binding associated wit h the synaptosomal sub-fraction and 19% with a light membrane fraction . Binding of H-3!-CGS 21680 was also found to co-purify with the chol inergic nerve terminal marker choline acetyltransferase during immunoa ffinity purification of striatal cholinergic nerve terminals. These re sults demonstrate that some adenosine A2a receptors are present on cho linergic nerve terminals in rat striatum.