Chronic L-dopa administration decreases striatal accumulation of dopamine from exogenous L-dopa in rats with intact nigrostriatal projections

Eldad Melamed, Mordechai Globus, Esther Friedlender, Jutta Rosenthal

Research output: Contribution to journalArticlepeer-review

Abstract

To examine whether chronic administration of L-dopa can affect its own utilization in striatum, rats were injected once daily for 30 days with L-dopa and carbidopa or with saline. On day 31, saline and L-dopa animals were sacrificed 1, 2, or 3 hours after L-dopa injection. In rats given long-term L-dopa, the elevations in striatal dopamine concentrations induced by L-dopa administration were smaller and of shorter duration than those in controls. Such changes did not occur in animals pretreated with L-dopa for only 10 days. Results suggest that prolonged L-dopa therapy may decrease striatal accumulation of dopamine from exogenous L-dopa even when the nigrostriatal projections are intact. Therefore, it is possible that declining efficacy of L-dopa in parkinsonism may be due to effects of the drug itself and not only to disease progression.

Original languageEnglish
Pages (from-to)950-953
Number of pages4
JournalNeurology
Volume33
Issue number7
DOIs
StatePublished - Jul 1983
Externally publishedYes

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