Activation of estradiol-positive feedback at puberty: Estradiol sensitizes the LHRH-releasing system at two different biochemical steps

Sergio R. Ojeda, Henryk F. Urbanski, Kathy H. Katz, Maria E. Costa

    Research output: Contribution to journalArticle

    44 Scopus citations

    Abstract

    Experiments were performed to examine whether estradiol (E2) can influence some of the intraneuronal mechanisms involved in luteinizing hormone-releasing hormone (LHRH) release during the onset of puberty in the female rat. The capacity of median eminence (ME) nerve terminals to secrete LHRH, as determined by both their basal release of LHRH and by their response to prostaglandin E2 (PGE2) in vitro, increased significantly during the juvenile-early peripubertal periods of development (postnatal days 22-34). Ovariectomy (OVX) on day 22 led to a striking reduction in LHRH response to PGE2 on day 34. E2 administered via s.c. Silastic capsules, at a dose that reproduces juvenile serum E2 levels, restored the response. Simulation of first proestrous serum E2 levels in late juvenile (28-day-old) female rats enhanced both the sensitivity and the responsivenes of LHRH-containing terminals to PGE2. Furthermore, E2 enhanced the sensitivity and the responsiveness of LHRH terminals to norepinephrine (NE). This effect appeared to be related to both the increased LHRH response to PGE2 and an enhanced sensitivity of the PGE2-synthesizing pathway to NE. This is because MEs from E2-treated rats showed a marked increase in PGE2 release in response to a NE concentration which was barely effective in untreated controls. It is suggested that one of the mechanisms by which E2 activates the first preovulatory discharge of LHRH release in the female rat is by facilitating the occurrence of two different but sequentially related biochemical events: The stimulation of PGE2 formation by NE and the enhancement of LHRH release by PGE2. In addition, it appears that maintenance of LHRH responsiveness to PGE2, which has been implicated as an obligatory component of NE-induced LHRH release, is E2-dependent.

    Original languageEnglish (US)
    Pages (from-to)259-265
    Number of pages7
    JournalNeuroendocrinology
    Volume43
    Issue number2
    DOIs
    StatePublished - Jan 1 1986

    Keywords

    • Estradiol
    • Female puberty
    • Luteinizing hormone-releasing hormone release
    • Norepinephrine
    • Prostaglandin E<inf>2</inf> release
    • edian eminence

    ASJC Scopus subject areas

    • Endocrinology, Diabetes and Metabolism
    • Endocrinology
    • Endocrine and Autonomic Systems
    • Cellular and Molecular Neuroscience

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