ENZYMATIC ISOTOPIC ASSAY FOR AND PRESENCE OF β‐PHENYLETHYLAMINE IN BRAIN

Abstract

Abstract— An enzymatic isotopic assay for the measurement of β‐phenylethylamine in brain, with a sensitivity of 100‐200 pg, has been developed. With this assay, the endogenous β‐phenylethylamine content (1.5 ng/g) in the rat brain has been determined. Phenylalanine administration increases the brain levels of this amine; inhibition of monoamine oxidase causes a 40‐fold increase in brain β‐phenylethylamine. After a combined treatment with a monoamine oxidase inhibitor and phenylalanine, the β‐phenylethylamine content in the brain increases to about 400‐fold. This increase can be blocked by the central decarboxylase inhibitor NSD‐1055. p‐Chlorophenylalanine also increases β‐phenylethylamipe concentration in the brain, and this effect is potentiated by a simultaneous administration of phenylalanine.