Prolactin secretion in response to prolactin-releasing peptide and the expression of the prolactin-releasing peptide gene in the medulla oblongata are estrogen dependent in rats

  • Tokita Reiko
    Department of Bioregulation, Institute of Gerontology, Nippon Medical School
  • Nakata Tomoko
    Department of Bioregulation, Institute of Gerontology, Nippon Medical School
  • Katsumata Harumi
    Department of Bioregulation, Institute of Gerontology, Nippon Medical School
  • Konishi Shunichiro
    Department of Bioregulation, Institute of Gerontology, Nippon Medical School
  • Onodera Hidetaka
    Department of Anatomy, Nippon Medical School
  • Imaki Junko
    Department of Anatomy, Nippon Medical School
  • Minami Shiro
    Department of Bioregulation, Institute of Gerontology, Nippon Medical School

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説明

Prolactin-releasing peptide (PrRP), recently isolated from bovine hypothalamus as an endogenous ligand to a seven transmembrane-domain orphan receptor, is a candidate specific prolactin-releasing factor. The prolactin-releasing activity of the peptide and the expression of the PrRP gene were examined in vivo in relation to estrogen status. Plasma prolactin levels increased significantly with a peak at 5 min after the administration of 50μg/kg PrRP in female rats in estrus under urethane anesthesia as compared with those in vehicle-treated control rats, but not in female rats in diestrus or proestrus or in male rats. In ovariectomized rats treated with supraphysiological concentration of estrogen, a dose-dependent increase of prolactin secretion in response to 2-50μg/kg PrRP was observed. However, the peak values induced by 50μg/kg PrRP were much less than those induced by 2μg/kg thyrotropin-releasing hormone (TRH). PrRP mRNA levels in the medulla oblongata were decreased by ovariectomy and increased by estrogen treatment. The data indicate that estrogen is prerequisite to the stimulatory effect of PrRP on the secretion of prolactin and to the increase of PrRP mRNA levels in the medulla oblongata. The weak in vivo potency of PrRP on prolactin secretion relative to TRH suggests that PrRP differs from the classical hypophysiotropic hypothalamic releasing hormones. [○!C]1999 Elsevier Science lreland Ltd. All rights reserved.

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詳細情報 詳細情報について

  • CRID
    1571980076768037248
  • NII論文ID
    110001801126
  • NII書誌ID
    AN1047681X
  • ISSN
    13409662
  • 本文言語コード
    en
  • データソース種別
    • CiNii Articles

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