Encyclopedia of toxicology, third edition. Wexler P, ed. San Diego, CA: Academic Press, 2014 Mar; 1:748-750
Catecholamines are endogenous neurotransmitters or hormones. Dopamine and norepinephrine are in the monoamine class. Catecholamines are synthesized in the brain, the adrenal medulla, and by some sympathetic nerve fibers. The biosynthesis of catecholamines begins with the hydroxylation of tyrosine by tyrosine hydroxylase to form L-dopa, which is decarboxylated by aromatic amino acid decarboxylase to form dopamine. Catecholamines are formed from dopamine by the enzyme dopamine beta-hydroxylase, and epinephrine is formed from norepinephrine by enzyme phenylethanolamine N-methyltransferase. Parkinson's disease is one of the most common neurodegenerative disorders and is characterized by the selective loss of dopaminergic neurons in the substantia nigra. Dopamine is widely distributed throughout the CNS and is involved in the control of movement. Dopamine is synthesized from the amino acid tyrosine. This amino acid is abundant in meats, dairy products, and soy. Tyrosine undergoes a series of enzymatic modifications to yield dopamine. The amount of dopamine that can be made is limited by the activity of the first enzyme in the synthesis chain - tyrosine hydroxylase. Cells that use dopamine as a neurotransmitter are referred to as dopaminergic. Norepinephrine is an important neurotransmitter in both the CNS and the sympathetic part of the autonomic nervous system. The hormone epinephrine acts together with the sympathetic nervous system to initiate the body's quick response to stressful stimuli.
Hormones; Neurological-system; Central-nervous-system; Neuromotor-function; Neuromotor-system; Neuromuscular-function; Neuromuscular-system;
Author Keywords: Catecholamines; Dopamine; Epinephrine; Neurons; Neurotransmitter; Norepinephrine; Sympathomimetic; Tyrosine
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Encyclopedia of toxicology, third edition