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norepinephrine (noradrenaline)
epinephrine (adrenaline)

A catecholamine (/kætəˈkləmin/) (CA) is a monoamine, an organic compound that has a catechol (benzene with two hydroxyl side groups at carbons 1 and 2) and a side-chain amine.[1]

Catechol can be either a free molecule or a substituent of a larger molecule, where it represents a 1,2-dihydroxybenzene group.

Catecholamines are derived from the amino acid tyrosine, which is derived from dietary sources as well as synthesis of phenylalanine.[2] Catecholamines are water-soluble and are 50%-bound to plasma proteins in circulation.

Included among catecholamines 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.[3]


Various stimulant drugs are catecholamine analogues.



Production and degradation[edit]

Biosynthetic pathways for catecholamines and trace amines in the human brain[5][6][7]
The image above contains clickable links
In humans, catecholamines (shown in yellow) are derived from the amino acid L-phenylalanine.
L-Phenylalanine is converted into L-tyrosine by an aromatic amino acid hydroxylase (AAAH) enzyme (phenylalanine 4-hydroxylase), with molecular oxygen (O2) and tetrahydrobiopterin as cofactors. L-Tyrosine is converted into L-DOPA by another AAAH enzyme (tyrosine 3-hydroxylase) with tetrahydrobiopterin, O2, and ferrous iron (Fe2+) as cofactors. L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase (AADC), with pyridoxal phosphate as the cofactor. Dopamine itself is also used as precursor in the synthesis of the neurotransmitters norepinephrine and epinephrine. Dopamine is converted into norepinephrine by the enzyme dopamine β-hydroxylase (DBH), with O2 and L-ascorbic acid as cofactors. Norepinephrine is converted into epinephrine by the enzyme phenylethanolamine N-methyltransferase (PNMT) with S-adenosyl-L-methionine as the cofactor.


Catecholamines are produced mainly by the chromaffin cells of the adrenal medulla and the postganglionic fibers of the sympathetic nervous system. Dopamine, which acts as a neurotransmitter in the central nervous system, is largely produced in neuronal cell bodies in two areas of the brainstem: the ventral tegmental area and the substantia nigra, the latter of which contains neuromelanin-pigmented neurons. The similarly neuromelanin-pigmented cell bodies of the locus ceruleus produce norepinephrine. Epinephrine is produced in small groups of neurons in the human brain which express its synthesizing enzyme, phenylethanolamine N-methyltransferase;[8] these neurons project from a nucleus that is adjacent (ventrolateral) to the area postrema and from a nucleus in the dorsal region of the solitary tract.[8]


Dopamine is the first catecholamine synthesized from DOPA. In turn, norepinephrine and epinephrine are derived from further metabolic modification of dopamine. The enzyme dopamine hydroxylase requires copper as a cofactor (not shown in the diagram) and DOPA decarboxylase requires PLP (not shown in the diagram). The rate limiting step in catecholamine biosynthesis through the predominant metabolic pathway is the hydroxylation of L-tyrosine to L-DOPA.














Function in plants[edit]


See also[edit]


  4. ^ Joh, T. H.; Hwang, O. (1987). "Dopamine Beta-Hydroxylase: Biochemistry and Molecular Biology". Annals of the New York Academy of Sciences. 493: 342–350. doi:10.1111/j.1749-6632.1987.tb27217.x. PMID 3473965. 
  8. ^ a b Kitahama K, Pearson J, Denoroy L, Kopp N, Ulrich J, Maeda T, Jouvet M (1985). "Adrenergic neurons in human brain demonstrated by immunohistochemistry with antibodies to phenylethanolamine-N-methyltransferase (PNMT): discovery of a new group in the nucleus tractus solitarius". Neurosci. Lett. 53 (3): 303–308. PMID 3885079. 
  10. ^ Brunner, H. G. (1996). "MAOA Deficiency and Abnormal Behaviour: Perspectives on an Association". Ciba Foundation Symposium. 194: 155–164; discussion 164–167. PMID 8862875. 
  11. ^ Kuklin, A. I.; Conger, B. V. (1995). "Catecholamines in Plants". Journal of Plant Growth Regulation. 14 (2): 91–97. doi:10.1007/BF00203119. 

External links[edit]