Dopamine receptor changes in response to prolonged treatment with L-dopa.

A. Groppetti, C. Flauto, E. Parati, Angelo Vescovi, L. Rusconi, M. Parenti

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Unilateral lesions of the nigro-striatal dopamine (DA) pathway induced contralateral rotations to apomorphine, increased (3H)-spiroperidol binding and enhanced the sensitivity of striatal adenylate cyclase to DA stimulation. Prolonged L-dopa administration counteracted the increased density of (3H)-spiroperidol binding sites but further enhanced the hypersensitivity of adenylate cyclase to DA and decreased the inhibitory effect of opiates on this enzyme. The apomorphine-induced contralateral rotations were also strongly potentiated. On the contrary the binding of (3H)-SCH-23390 was affected neither by DA nerve degeneration nor by chronic L-dopa treatment. These results suggest that DA-D1 and DA-D2 receptors are differently affected by prolonged L-dopa treatment. The biochemical changes of DA-D1 receptors associated with adenylate cyclase seem to be correlated with the enhanced behavioural responses to apomorphine and could be a consequence of a decreased opiate inhibitory tone on the enzyme. The increased supersensitivity of the DA-D1 receptors may play a role in the clinical changes seen in parkinsonian patients following chronic use of L-dopa.

Original languageEnglish (US)
Pages (from-to)33-45
Number of pages13
JournalJournal of Neural Transmission, Supplement
Volume22
StatePublished - Dec 1 1986

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Psychiatry and Mental health
  • Biological Psychiatry

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