Serotonin Synthesis in Carcinoid Patients

Abstract

RECENT investigations in our laboratories have shown that α-methyl-3,4-dihydroxy-DL-phenylalanine (α-methyl-dopa) is an effective inhibitor of aromatic amino acid decarboxylation in man.¹ Among other things it was found that the increased urinary excretion of 5-hydroxytryptamine (serotonin) that occurs after infusion of 5-hydroxytryptophan (5-HTP) in noncarcinoid subjects was reduced greatly during treatment with α-methyl-dopa. Since excessive production of serotonin is thought to account for many of the symptoms in the carcinoid syndrome, attempts to inhibit the decarboxylation of 5-HTP in carcinoid patients constitute a logical approach to therapy. Therefore, studies with α-methyl-dopa utilizing a sensitive and specific method for measuring 5-HTP in . . .