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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 ...
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Catecholamine production levels return to normal 72 to 96 hours after administration of the drug ceases. [11] Dosages as low as 300 mg per day have been found to have an effect on catecholamine production, which can be measured through urinary excretion analysis and cerebral spinal fluid assays. [ 9 ]
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
This enzyme methylates catecholamines such as dopamine, norepinephrine and epinephrine. It also methylates levodopa. COMT inhibitors are indicated for the treatment of Parkinson's disease in combination with levodopa and an aromatic L-amino acid decarboxylase inhibitor (e.g. carbidopa or benserazide).
Norepinephrine degradation. Catechol-O-methyltransferase is shown in green boxes.[5] [6]Catechol-O-methyltransferase (COMT; EC 2.1.1.6) is one of several enzymes that degrade catecholamines (neurotransmitters such as dopamine, epinephrine, and norepinephrine), catecholestrogens, and various drugs and substances having a catechol structure. [7]
Catecholaminergic means "related to catecholamines". The catecholamine neurotransmitters include dopamine , epinephrine (adrenaline), and norepinephrine (noradrenaline). A catecholaminergic agent (or drug ) is a chemical which functions to directly modulate the catecholamine systems in the body or brain.
Homovanillic acid (HVA) is a major catecholamine metabolite that is produced by a consecutive action of monoamine oxidase and catechol-O-methyltransferase on dopamine. [1] Homovanillic acid is used as a reagent to detect oxidative enzymes , and is associated with dopamine levels in the brain .