Increased stress response and beta-phenylethylamine
in MAOB-deficient mice

Grimsby J; Toth M; Chen K; Kumazawa T;
Klaidman L; Adams JD; Karoum F; Gal J; Shih JC
Department of Molecular Pharmacology and Toxicology,
School of Pharmacy,
University of Southern California,
Los Angeles 90033, USA
Nat Genet, 1997 Oct, 17:2, 206-10


MAOA and MAOB are key iso-enzymes that degrade biogenic and dietary amines. MAOA preferentially oxidizes serotonin (5-hydroxytryptamine, or 5-HT) and norepinephrine (NE), whereas MAOB preferentially oxidizes beta-phenylethylamine (PEA). Both forms can oxidize dopamine (DA). A mutation in MAOA results in a clinical phenotype characterized by borderline mental retardation and impaired impulse control. X-chromosomal deletions which include MAOB were found in patients suffering from atypical Norrie's disease, which is characterized by blindness and impaired hearing. Reduced MAOB activity has been found in type-II alcoholism and in cigarette smokers. Because most alcoholics smoke, the effects of alcohol on MAOB activity remain to be determined. Here we show that targetted inactivation of MAOB in mice increases levels of PEA but not those of 5-HT, NE and DA, demonstrating a primary role for MAOB in the metabolism of PEA. PEA has been implicated in modulating mood and affect. Indeed, MAOB-deficient mice showed an increased reactivity to stress. In addition, mutant mice were resistant to the neurodegenerative effects of MPTP, a toxin that induces a condition reminiscent of Parkinson's disease.

The Chocuhaler
PEA and exercise
Food of the gods?
Chocolate: history
Chocolate hotlinks
PEA and dopamine
Stoned chocaholics?
PEA and antidepressants
Chocolate: food or drug?
PEA and antidepressants
The endogenous amphetamine?