The availability of the most selective, high-affinity, natural opioid agonists for mu-receptors (dermorphin-DM) and delta-receptors (deltorphin-DT) has provided the possibility for in vivo studying of the role of acute and chronic activation of mu- and delta-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 beta-endorphin-like-immunoreactivity (beta-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 mu-receptor agonist, enhanced basal and stress induced plasma levels of CS and beta-EP-LI. These effects were antagonized by pretreatment with naloxone, specific mu-opioid receptor antagonist, but not by naltrindole, a delta-opioid receptor antagonist. Long-term administration of DM did not alter resting plasma levels of CS and beta-EP-LI, but significantly reduced stress-induced increase of these hormones. Both the acute and chronic administration of the DT, highly selective delta-opioid receptors agonist, failed to modify resting and stress induced hormone levels. Our present data show that DM throughout mu-opioid receptors, but not DT, modulates the response of HPA axis to acute stress in rats, increasing or decreasing the release of CS and beta-EP-LI when acutely or chronically administered, respectively.
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|Titolo:||Involvement of mu-opioid receptors in the modulation of pituitary-adrenal axis in normal and stressed rats.|
|Rivista:||JOURNAL OF ENDOCRINOLOGICAL INVESTIGATION|
|Citazione:||degli Uberti, E.c., Petraglia, F., Bondanelli, M., Guo, A.l., Valentini, A., Salvadori, S., et al. (1995). Involvement of mu-opioid receptors in the modulation of pituitary-adrenal axis in normal and stressed rats. JOURNAL OF ENDOCRINOLOGICAL INVESTIGATION, 18(1), 1-7.|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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