Catecholamines are the class of MONOAMINE that contain a catechol nucleus and a side chain of ethylamine or one of its derivatives. CATECHOLAMINERGIC is the term used to describe cells—usually neurons—that contain catecholamines. The most important catecholamines are DOPAMINE, NORADRENALINE and ADRENALINE, which are small-molecule neurotransmitters. The latter two are also called NOREPINEPHRINE (NE) and EPINEPHRINE, respectively, these being the standard American terms (in contrast to noradrenaline and adrenaline, which are the English terms).
The difference in terminology comes from the fact that in the United Kingdom adrenaline was first extracted from the ADRENAL GLAND while almost simultaneously in the United States it was synthesized from kidney tissue (the nephron). The precursor for all catecholamines is TYROSINE, derived from dietary protein. Tyrosine is converted into DOPA, dopamine, noradrenaline, and finally to adrenaline. TYROSINE HYDROXYLASE is the rate-limiting enzyme in this synthetic pathway. The specific enzymes that catalyse each step of this pathway have been used as anatomical markers for neurons that contain dopamine, noradrenaline and adrenaline.
KAZUE SEMBA
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