Differential time course of effects of κ-opioid agonist treatment on dynorphin A levels and κ-opioid receptor density

Claudio D'Addario, Manuela Di Benedetto, Sari Izenwasser, Sanzio Candeletti, Patrizia Romualdi

Research output: Contribution to journalArticle

6 Scopus citations


The effects of κ-opioid agonist treatment on κ-opioid receptor density and on dynorphin A levels in the rat brain were studied. Rats were treated with the selective κ-opioid agonist U-69593 or vehicle for 5 d. Dynorphin A levels and κ-opioid receptor binding were measured on day 8 (3 d after the last injection) or 22 (17 d after the last injection). On day 8, κ-opioid receptor density was increased in the hypothalamus of rats treated with U-69593; there were no changes in the frontal cortex or caudate putamen. In contrast, there was an increase in dynorphin A levels in the frontal cortex and no changes in hypothalamus and caudate putamen in response to U-69593. On day 22, Bmax was decreased in frontal cortex and caudate putamen of U-69593-treated rats, whereas dynorphin A levels were increased in the caudate putamen and in the frontal cortex. These findings suggest that κ-opioid receptor agonist treatment has long-term, continually changing effects on the κ-opioid system.

Original languageEnglish (US)
Pages (from-to)307-314
Number of pages8
JournalJournal of Molecular Neuroscience
Issue number2
StatePublished - Sep 1 2004



  • κ-receptor
  • Dynorphin A
  • Opioids
  • Rat
  • U-69593

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry
  • Genetics

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