Involvement of μ-opioid receptors in the modulation of pituitary-adrenal axis in normal and stressed rats

E. C. degli Uberti, F. Petraglia, M. Bondanelli, A. L. Guo, A. Valentini, S. Salvadori, M. Criscuolo, R. E. Nappi, A. R. Genazzani

Research output: Contribution to journalArticlepeer-review


The availability of the most selective, high-affinity, natural opioid agonists for μ-receptors (dermorphin-DM) and δ-receptors (deltorphin-DT) has provided the possibility for in vivo studying of the role of acute and chronic activation of μ-and δ-opioid receptors on the functional activity of the hypothalamus-pituitary-adrenocortical (HPA) axis, both in basal conditions and in response to an acute stress in adult male rats. Plasma corticosterone (CS) and ß-endorphin-like-immunoreactivity (ß-EP-LI) levels were measured by specific radioimmunoassays before and after 5 and 30 minutes from the exposure to cold (3±0.5 C) water and forcing them to swim for 10 minutes (acute cold swimming stress). Acute administration of DM, the specific μ-receptor agonist, enhanced basal and stress induced plasma levels of CS and ß-EP-LI. These effects were antagonized by pretreatment with nalox-one, specific μ-opioid receptor antagonist, but not by naltrindole, a δ-opioid receptor antagonist. Long-term administration of DM did not alter resting plasma levels of CS and ß-EP-LI, but significantly reduced stress-induced increase of these hormones. Both the acute and chronic administration of the DT, highly selective δ-opioid receptors agonist, failed to modify resting and stress induced hormone levels. Our present data show that DM throughout μ-opioid receptors, but not DT, modulates the response of HPA axis to acute stress in rats, increasing or decreasing the release of CS and ß-EP-LI when acutely or chronically administered, respectively.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalJournal of Endocrinological Investigation
Issue number1
Publication statusPublished - 1995


  • Corticosterone
  • deltorphin
  • dermorphin
  • ß-endorphin
  • stress
  • δ-receptors
  • μ-receptors

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism


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