Acute administration of estrogen suppresses LH secretion without altering GnRH release in ovariectomized rhesus macaques

K. Y.Francis Pau, Perry M. Gliessman, David L. Hess, Oline K. Ronnekleiv, Jon E. Levine, Harold G. Spies

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The pattern of hypothalamic gonadotropin-releasing hormone (GnRH) release was examined during estrogen (E)-induced suppression of plasma luteinizing hormone (LH) in ovariectomized (OVX) rhesus macaques. In Expt. 1, 4 OVX macaques were fitted with a jugular catheter and a push-pull cannula (PPC) directed into the median eminence (ME). Push-pull perfusion (PPP) was initiated 10 h before and continued for 10 h after subcutaneous estradiol benzoate (EB) injection (42 μg/kg b.wt.). In Expt. 2, 4 additional monkeys were subjected to local intrahypothalamic perfusion with estradiol-17β (E2, 3 μM) for the last 10 h of a 20-h PPP. In Expt. 3, OVX animals were challenged with 5 μg exogenous GnRH 3 h before and 8 h after EB injection to test for changes in altered LH release. Integrated 10-min ME perfusate and intermittent 10- or 60-min peripheral plasma samples were assayed for GnRH and LH by radioimmunoassay and bioassay, respectively. In addition, 2 other OVX macaques that received similar ME-PPC placement were sacrificed 2 days after the completion of a PPP for immunocytochemical labeling of GnRH neurons at the perfusion site. The results show that after EB, hypothalamic GnRH (MBH-GnRH) release remained unaltered while LH levels declined rapidly (Expt. 1). Similarly, intrahypothalamic perfusion of E2 failed to change the pattern of MBH-GnRH release in any of 4 monkeys (Expt. 2). Conversely, plasma LH release in response to exogenous GnRH was greatly reduced after EB (Expt. 3). Immunocytochemically labeled GnRH-containing nerve fibers and cell bodies were observed adjacent to the site of PPP in the 2 monkeys examined after the completion of 20 h of PPP. Collectively, these data suggest that acute administration of E exerts immediate negative feedback effects at the pituitary through a process that is unrelated to changes in patterns of mediobasal hypothalamic GnRH release.

Original languageEnglish (US)
Pages (from-to)229-235
Number of pages7
JournalBrain research
Volume517
Issue number1-2
DOIs
StatePublished - May 28 1990

Keywords

  • Estrogen
  • Hypothalamic gonadotropin-releasing hormone
  • Luteinizing hormone
  • Negative feedback
  • Rhesus monkey

ASJC Scopus subject areas

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

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