Demonstration and distribution of phenylethanolamine in brain and other tissues.

A specific and sensitive assay for phenylethanolamine in tissues is described. By this assay, phenylethanolamine was detected in many peripheral tissues and brains of rats. It is unequally distributed in rat brain, with the highest concentration present in hypothalamus and midbrain. Concentrations of brain phenylethanolamine were elevated after administration of phenylethylamine, phenylalanine, p-chlorophenylalanine, and monoamine oxidase inhibitors and decreased after administration of dopamine-beta-hydroxylase inhibitors. Denervation of sympathetic nerves caused a moderate fall in phenylethanolamine concentrations. These results indicate that phenylethanolamine is synthesized intraneuronally from phenylalanine and phenylethylamine, but that only part of the phenylethanolamine is stored in sympathetic nerves.