Tyramine

Tyramine is a naturally occurring trace amine formed by removing a carboxyl group from tyrosine. It occurs in foods and can promote the release of neurotransmitters, especially norepinephrine.

Trace amines: Trace amines are low-abundance biogenic amines found in the nervous system and other tissues. Tyramine is a trace amine whose physiological effects arise despite its low abundance.
Monoamine oxidase inhibitor: A monoamine oxidase inhibitor is a drug that reduces enzymatic breakdown of monoamine neurotransmitters. These drugs can prevent tyramine breakdown and make dietary exposure more consequential.
Tyrosine: Tyrosine is an amino acid used in protein synthesis and as a precursor to catecholamines and other molecules. Removing tyrosine’s carboxyl group produces tyramine.
Phenylethylamine: Phenylethylamine is a naturally occurring trace amine and neuromodulator structurally related to tyramine. Both are trace amines, but their metabolism and pharmacological profiles differ.
Monoamine transporter: Monoamine transporters move neurotransmitters and related amines across cell membranes. Tyramine uses transport systems that normally handle monoamine neurotransmitters.
Tyramine pressor response: The tyramine pressor response is a rise in blood pressure caused by tyramine-induced catecholamine release. It demonstrates how tyramine’s indirect action can increase vascular tone and blood pressure.
Decarboxylation: Decarboxylation is a chemical reaction that removes a carboxyl group, releasing carbon dioxide. Tyrosine decarboxylation is the direct biochemical route to tyramine.
Octopamine: Octopamine is a biogenic amine that functions as a neurotransmitter in many invertebrates and has limited roles in mammals. It is another trace amine, but its prominent signaling roles differ from tyramine’s in mammals.
Vesicular monoamine transporter 2: VMAT2 is a membrane protein that packages monoamines into intracellular storage vesicles. Tyramine can enter storage vesicles through VMAT2 and displace stored monoamines.
Hypertensive crisis: A hypertensive crisis is a severe elevation in blood pressure requiring urgent assessment. Excess tyramine during monoamine oxidase inhibition can rarely precipitate a dangerous pressure rise.

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