Opioids modify the release of LH at the pituitary level in vitro studies with entire rat pituitaries

Ioannis Dragatsis, P. Papazafiri, C. Zioudrou, K. Gerozissis

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

It is currently accepted that opioids modify the secretion of LH by affecting the release of GnRH in the hypothalamus. A direct action of opioids at the pituitary level is not yet fullly established. To this end, we tested the effects of opioids on the release of LH by the entire pituitary in adult male rats. Opioid agonists with mu (DAGO), delta (DSLET) and kappa (U-50488H) specificity were tested at 0.01 to 10 μM in static incubations. DAGO inhibited dose-dependently the spontaneous and GnRH-induced release of LH. DSLET inhibited only the GnRH-induced release of LH. On the other hand, U-50488H increased spontaneous LH release dose-dependently. The opioid antagonists naloxone, diallyl-G (delta antagonist) and MR 2266 (kappa antagonist) blocked the effects induced by DAGO, DSLET or U-50488H respectively, implying an opioid receptor-mediated effect. The above results showed that opioids with mu, delta and kappa specificity act on the entire pituitary and modify differentially the release of LH. In this study we also compared spontaneous and GnRH-induced LH release by anterior and entire pituitaries and found that the amount of LH released by the anterior lobe was twofold higher, suggesting that inhibitory factors present in the neurointermediate part may affect the release of LH.

Original languageEnglish (US)
Pages (from-to)263-270
Number of pages8
JournalJournal of Endocrinology
Volume145
Issue number2
DOIs
StatePublished - Jan 1 1995
Externally publishedYes

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enkephalin, Ser(2), Leu(5), Thr(6)-
Opioid Analgesics
(trans)-Isomer 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide
Ala(2)-MePhe(4)-Gly(5)-enkephalin
Gonadotropin-Releasing Hormone
Narcotic Antagonists
Opioid Receptors
Naloxone
Hypothalamus
In Vitro Techniques

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Cite this

Opioids modify the release of LH at the pituitary level in vitro studies with entire rat pituitaries. / Dragatsis, Ioannis; Papazafiri, P.; Zioudrou, C.; Gerozissis, K.

In: Journal of Endocrinology, Vol. 145, No. 2, 01.01.1995, p. 263-270.

Research output: Contribution to journalArticle

Dragatsis, Ioannis ; Papazafiri, P. ; Zioudrou, C. ; Gerozissis, K. / Opioids modify the release of LH at the pituitary level in vitro studies with entire rat pituitaries. In: Journal of Endocrinology. 1995 ; Vol. 145, No. 2. pp. 263-270.
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