Does phenylethylamine act as an endogenous amphetamine in some patients?
In brain capillary endothelium and catecholaminergic terminals a single decarboxylation step effected by aromatic amino-acid decarboxylase converts phenylalanine to phenylethylamine, at a rate comparable to that of the central synthesis of dopamine. Phenylethylamine, however, is not stored in intra-neuronal vesicles and is rapidly degraded by monoamine oxidase-B. Despite its short half-life, phenylethylamine attracts attention as an endogenous amphetamine since it can potentiate catecholaminergic neurotransmission and induce striatal hyperreactivity. Subnormal phenylethylamine levels have been linked to disorders such as attention deficit and depression; the use of selegiline (Deprenyl) in Parkinson's disease may conceivably favour recovery from deficient dopaminergic neurotransmission by a monoamine oxidase-B inhibitory action that increases central phenylethylamine. Excess phenylethylamine has been invoked particularly in paranoid schizophrenia, in which it is thought to act as an endogenous amphetamine and, therefore, would be antagonized by neuroleptics. The importance of phenylethylamine in mental disorders is far from fully elucidated but the evolution of phenylethylamine concentrations in relation to symptoms remains a worthwhile investigation for individual psychotic patients.(Received November 25 1998)
(Reviewed January 18 1999)
(Revised May 27 1999)
(Accepted May 30 1999)
Key Words: Amphetamine; aromatic amino-acid decarboxylase; dopamine; phenylethylamine; schizophrenia.
c1 Address for correspondence: Dr F. H. L. Awouters, Centre for Molecular Design, Janssen Research Foundation, Antwerpsesteenweg 37, B-2350 Vosselaar, Belgium. Tel.: 32-14-61 20 60 Fax: 32-14-43 73 34 E-mail: [email protected]