One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.
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.