ABSENCE OF 2-PHENYLETHYLAMINE BINDING AFTER MONOAMINE-OXIDASE INHIBITION IN RAT-BRAIN

Earlier work has suggested the existence of saturable and highly specific binding sites for [H-3]2-phenylethylamine in rat forebrain membranes. Since monoamine oxidase (MAO) was not inhibited during the assay, the [H-3]2-phenylethylamine binding may have been affected by an interaction between 2-phenylethylamine and the enzyme. This is an investigation of [H-3]2-phenylethylamine binding to rat forebrain membranes in the presence of two MAO inhibitors, ( )-deprenyl and pargyline. The results show that the high affinity specific binding of [H-3]2-phenylethylamine to rat forebrain membranes is inhibited by pretreatment of the membrane with the MAO inhibitors and in vivo injection of the MAO inhibitors in a concentration-dependent manner. In the presence of higher concentrations of MAO inhibitors, the specific binding of [H-3]2-phenylethylamine is completely blocked, suggesting that the binding sites reported earlier represent binding to MAO-B.