Dec 1, 1975

The neurochemistry of Parkinson's disease: effect of L-dopa therapy

The Journal of Pharmacology and Experimental Therapeutics
K G LloydO Hornykiewicz


Post-mortem brain material from control and Parkinson's disease patients was examined to elucidate further the neurochemistry of this disease and to determine the mechanism of action of L-dopa as a therapeutic agent. The activities of L-aromatic amino acid decarboxylase (dopa D), tyrosine hydroxylase, monoamine oxidase and catechol-O-methyl transferase were examined; in addition the tissue levels of dopa, 3-O-methyldopa, dopamine (DA) and homovanillic acid (HVA) were determined. In the non-dopa-treated Parkinsonian patients, the greatest decreases were detected for striatal DA and dopa D, with homovanillic acid and tyrosine hydroxylase levels showing a lesser change. The activities of monoamine oxidase and catechol-O-methyl transferase in the striatal nuclei were not different from the controls. The putamen was consistently the most severely affected region. Dopa and 3-O-methyldopa were detectable in all brain areas only in those patients treated with L-dopa shortly before death. The mean concentrations of DA in the striatum of these patients were 1) 9 to 15 times higher than those in non-dopa-treated patients, 2) related to the time before death of the last dose of L-dopa and 3) greater in the striatum of patients clinically c...Continue Reading

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Mentioned in this Paper

Striatonigral Degeneration, Infantile (Disorder)
Homovanillic Acid
Congenital Abnormal Synostosis
Monoamine Oxidase
Dihydroxyphenylalanine Hydrochloride, (2:1)
Parkinson Disease
DOPA decarboxylase

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