L-DOPA

L-DOPA (levodopa, 3,4-dihydroxy-L-phenylalanine). As a drug it is used to treat parkinsonism. L-DOPA is able to pass the blood-brain barrier as a prodrug and is decarboxylated in the brain to the neurotransmitter dopamine by the enzyme aromatic-L-amino-acid decarboxylase. In this way, L-DOPA can replace the some of the deficit in dopamine seen in parkinsonism. A possible side effect of L-DOPA is a condition similar to amphetamine psychosis.

In work that earned him a Nobel Prize, Swedish scientist Arvid Carlsson first showed in the 1950s that administering L-DOPA to animals with Parkinson's Disease-like symptoms would cause a reduction of the symptoms. The neurologist Oliver Sacks describes this treatment in human patients in his book Awakenings on which the movie of the same name is based.