Gourt Home::Gourt :: Tyramine
In organic chemistry tyramine (4-hydroxy-phenethylamine, para-tryamine, p-tyramine) is a monoamine compound derived from the amino acid tyrosine.
Occurrence
It occurs widely in plants and animals and is metabolized by the enzyme monoamine oxidase. In foods, it is often produced by the decarboxylation of tyrosine during fermentation or decay. Foods containing considerable amounts of tyramine include fish, chocolate, alcoholic beverages, and fermented foods such as cheese, soy sauce and soy bean condiments, sauerkraut, and processed meat.
Metabolism
In humans, if tyramine metabolism is compromised by the use of monoamine oxidase inhibitors (MAOIs) and foods high in tyramine are ingested, a hypertensive crisis can result. The first signs of this were discovered by a neurologist who noticed his wife, who at the time was on MAOI medication, had severe headaches when eating cheese. For this reason, the crisis is still called the "cheese syndrome", even though other foods can cause the same problem.
Effects
A large dietary intake of tyramine can cause the tyramine pressor response which is defined as an increase in systolic blood pressure of 30 mmHg or more. The displacement of noradrenaline from neuronal storage vesicles by tyramine is thought to cause the vasoconstriction, and increased heart rate and blood pressure of the pressor response. The possibility that tyramine acts directly as a neurotransmitter comes from the discovery of a G protein-coupled receptor with high affinity for tyramine called TA1. The TA1 receptor is found in the brain as well as peripheral tissues including the kidney. A receptor with high affinity for tyramine supports the hypothesis that tyramine may also act directly to affect blood pressure regulation.
Migraine
Dietary tyramine intake has also been associated with migraine in select populations, leading many sufferers to restrict foods high in tyramine. Reports on the tyramine-migraine link have been both affirmed and denied. A recent review article found that all past studies affirming a migraine-tyramine connection were scientifically inconclusive, and noted several studies showing no connection. Two studies validated as scientifically sound reported no connection in the population evaluated. Despite lack of conclusive scientific evidence, anecdotal evidence citing decrease in migraines with a tyramine restricted diet abounds. An explanation for this can perhaps be found via research that while not finding a definite link between tyramine and migraine, measured elevated concentrations of trace amines, including tyramine, in select primary headache patients. Perhaps some alteration in trace amine metabolism in migraine suffers allows for an increased concentration of tyramine to accumulate. Since migraines are caused by cerebral vasoconstriction followed by dilation (throbbing), it is possible that the vasoactive effect of tyramine can trigger migraines. The implication for all people affected with migraine is the possible need for information regarding the tyramine content of their food. Such information will allow migraine sufferers finding migraine relief from lowered tyramine intake to follow a tyramine-restricted diet.
See also
External links
Migraine | Monoamine oxidase inhibitors | Phenethylamines | Phenols
"Tyramine"