Tyramine (Uteramine) is an indirect sympathomimetic that occurs naturally in cheese and other foods. Tyramine does not directly activate adrenergic receptors, but it can serve as a substrate for adrenergic uptake systems and MONOAMINE OXIDASE to prolong the actions of adrenergic transmitters. It also provokes transmitter release from adrenergic terminals and may be a neurotransmitter in some invertebrate nervous systems.