Presence of opiate receptors on striatal serotoninergic nerve terminals

Marco Parenti, Felice Tirone, Vincenzo R. Olgiati, Antonio Groppetti

Research output: Contribution to journalArticlepeer-review


After degeneration of serotoninergic neurons induced by either transection of the ascending neuronal pathways originating from the nucleus raphe dorsalis or intraventricular 5,6-dihydroxytryptamine administration, the number of binding sites for [3H]d-Ala2, Met5-enkephalinamide was significantly reduced. This decrease in binding sites does not seem to be related to the opiate receptors present on dopaminergic terminals, nor is it due to a simple decrease in serotoninergic neuronal tone, since after p-chlorophenylalanine (100 mg/kg × 4 days) the number of striatal binding sites for the opiate ligand was not diminished. On the other hand, shortly after mechanical interruption of the raphe-striatal serotoninergic fibers, at a time when the metabolic processes are still functioning in the lesioned neurons, morphine still increased the striatal content of 5-hydroxyindoleacetic acid. These results suggest the presence of opiate receptors on striatal serotoninergic terminals, where they may modulate the presynaptic activity of these neurons.

Original languageEnglish
Pages (from-to)317-322
Number of pages6
JournalBrain Research
Issue number2
Publication statusPublished - Dec 5 1983


  • 5 serotonin release
  • opiate receptors localization
  • serotonin terminals
  • striatum

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)


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