Tyramine

Tyramine is a naturally occurring monoamine compound and trace amine derived from the amino acid tyrosine. Tyramine acts as a catecholamine releasing agent. It is unable to cross the blood-brain barrier, resulting in non-psychoactive peripheral sympathomimetic effects following ingestion. A hypertensive crisis can result, however, from ingestion of tyramine-rich foods in conjunction with monoamine oxidase inhibitors (MAOIs).

Tyramine 3D ball

Sources

Tyramine occurs widely in plants and animals, and is metabolized by various enzymes, including monoamine oxidases. In foods, it often is produced by the decarboxylation of tyrosine during fermentation or decay. Foods containing considerable amounts of tyramine include meats that are potentially spoiled or pickled, aged, smoked, fermented, or marinated (e.g., herring, beef liver, and chicken liver), most cheese (except ricotta, cottage, cream and Neufchâtel cheeses), alcoholic beverages, and some fruits and vegetables. Certain processed foods often contain tyramine, including sausages, hot dogs, and certain types of bread.

Pharmacology

Tyramine can, by acting as an adrenergic agonist, cause the release of norepinephrine from storage vesicles in presynaptic neurons, increasing its level in the synaptic cleft and therefore its effects on post-synaptic adrenergic receptors. If foods containing tyramine are consumed by patients taking monoamine oxidase inhibitors, the sudden increase in synaptic norepinephrine can lead to a hypertensive crisis.

See also

• Histamine
• Phenethylamine
• Tryptamine