Dopa

A precursor (forerunner) of dopamine, a key neurotransmitter (messenger) in the brain. Dopa is used in the treatment of Parkinson disease. Parkinson disease is believed to be related to low levels of dopamine in certain parts of the brain. When dopa is taken by mouth, it crosses through the blood-brain barrier. Once it has crossed from the bloodstream into the brain, it is converted to dopamine. The resulting increase in dopamine concentrations in the brain is thought to improve nerve conduction and to assist in lessening the movement disorders in Parkinson disease. In 1970 the FDA (Food and Drug Administration) approved dopa in the form of L-Dopa, or levodopa, for use in the US. The drug revolutionized the treatment of Parkinson disease.

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dihydroxyphenylalanine

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do·pa 'dō-pə, -(.)pä n an amino acid C₉H₁₁NO₄ that in the levorotatory form is found in the broad bean and is used in the treatment of Parkinson's disease called also dihydroxyphenylalanine

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n.

dihydroxyphenylalanine: a physiologically important compound that forms an intermediate stage in the synthesis of catecholamines (dopamine, adrenaline, and noradrenaline) from the essential amino acid tyrosine. It also plays a role itself in the functioning of certain parts of the brain. The laevorotatory form, levodopa, is administered for the treatment of parkinsonism, in which there is a deficiency of the neurotransmitter dopamine in the brain.

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do·pa (doґpə) 3,4-dihydroxyphenylalanine, an amino acid produced by oxidation of tyrosine by monophenol monooxygenase; it is the precursor of dopamine and an intermediate product in the biosynthesis of norepinephrine, epinephrine, and melanin. The naturally occurring form is L-dopa (see levodopa).