<unk> echol dopamine norepinephrine (noradrenaline) epinephrine (adrenaline) A<unk>  (; abbreviated<unk>  is a monoamine neurotransmitter, an organic compound that has a<unk> echol (benzene with two hydroxyl side groups next to each other) and a side-chain amine.<unk> echol<unk> n be either a free molecule or a substituent of a larger molecule, where it represents a 1,2-dihydroxybenzene group.<unk> s are derived from the amino acid tyrosine, which is derived from dietary sources as well as synthesis from phenylalanine.<unk> s are water-soluble and are 50% bound to plasma proteins in circulation. Included among<unk> s are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. Release of the hormones epinephrine and norepinephrine from the adrenal medulla of the adrenal glands is part of the fight-or-flight response. Tyrosine is created from phenylalanine by hydroxylation by the enzyme phenylalanine hydroxylase. Tyrosine is also ingested directly from dietary protein.<unk> -secreting cells use several reactions to convert tyrosine serially to L-DOPA and then to dopamine. Depending on the cell type, dopamine may be further converted to norepinephrine or even further converted to epinephrine. Various stimulant drugs (such as a number of substituted amphetamines) are<unk>  analogues.
Catecholamine
Octopamine
Synephrine
Dopamine 
Dopamine
Serotonin
Somatostatin
Neuropil