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1995 Fiscal Year Final Research Report Summary

Demonstration that the neural network for the LHRH surge generator is distinct from that for the pulse generator.

Research Project

Project/Area Number 06454708
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Neuroscience in general
Research InstitutionYOKOHAMA CITY UNIVERSITY

Principal Investigator

TANAKA Fukuko (貴邑 冨久子)  Yokohama City University School of Medicine, Professor, 医学部, 教授 (40046066)

Co-Investigator(Kenkyū-buntansha) MITSUSHIMA Dai  Yokohama City University School of Medicine, Instructor, 医学部, 助手 (70264603)
FUNABASHI Toshiya  Yokahama City University School of Medicine, Assistant Professor, 医学部, 講師 (70229102)
Project Period (FY) 1994 – 1995
KeywordsLHRH neurons / Preoptic area / Positive feedback / Phasic LH secretion / MBH / Negative feedback / Tonic LH secretion / GABA neurons / Opioid neurons
Research Abstract

In the present study, we revealed, by means of electrophysiological, immunohistochemical and molecular biological methods, that two distinct subgroups of LHRH neurons are involved in the control of two different modes of gonadotropin secretion, i.e., one is for preovulatory surge secretion and the other for pulsatile secretion, .
1.LHRH surge generating neuronal system
In the rat, LHRH neurons located in the preoptic area constitutes the LHRH surge generator with GABA neurons as an estrogen-responsive element. The generator receives the clock information from the suprachiasmatic nucleus (SCN) probably through neuronal pathways. Estrogen affects GABA neuronal activity by acting at mRNA transcriptional level and increasing glutamic acid dehydrogenase, and exerts inhibition on LHRH neurons. The inhibition mediated by GABA neurons is disrupted somehow in the afternoon of proestrus to make the surge of LHRH secretion. We are currently studying what is the mechanism for disrupting inhibition by GABA neurons on LHRH neurons and what kind of neurons send clock information from the SCN to the surge generator.
2.LHRH pulse generating neuronal system
LHRH neurons located in the mediobasal hypothalamus constitute the LHRH pulse generator with opioid neurons as a mediator of negative feedback effects of estrogen. We are focussing the current study on what is the mechanism of synchronizing firing in LHRH neurons.

  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] Kimura,F.and Jinnai,K.: "Bicuculline infusions advance the timing of luteinizing hormone surge in proestrous rats ; Comparisions with naloxone effects." HORMONES AND BEHAVIOR. 28. 424-430 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kimura,F.and Sano,A.: "The effect of pentobarbital on the electrical activity of LHRH polse generator in the ovariectomized rat with or without estrogen priming." Journal of Neuroendocrinology. 7. 911-915 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kimura,F.,Jinnai,K.and Sano,A.: "LHRH pulse generator is stimulated by naloxone in the pentobarbital-blocked proestrous rat." Journal of Neuroendocrinology. 7. 917-922 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Funabashi,T.,Jinnai,K.and Kimura,F.: "Fos expression by naloxone in LHRH neurons of the mediobasal hypothalamus and effects of pentobarbital sodium in the proestrous rat." Journal of Neuroendocrinology. 9. 87-92 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Funabashi,T.,Jinnai,K.and Kimura,F.: "Bicuculline infusion advances the timing of Fos expression in LHRH neurons in the preoptic area of proestrous rats." Neuro Report. (印刷中). (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Mitsushima,D.,Jinnai,K.and Kimura,F.: "Possible role of the γ-aminobutyric acid-A receptor system in the timing of the proestrous luteinizing hormone surge in rats." Endocrinology. (印刷中). (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kimura, F.: "Bicuculline infusions advance the timing of luteinizing hormone surge in proestrous rats ; Compariosns with naloxone effects." Horm.Behav.28. 424-430 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kimura, F.: "The effect of pentobarbital on the electrical activity of LHRH pulse generator in the ovariectomized rat with or without estrogen priming." J.Neuroendocrinol. 7. 911-915 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kimura, F.: "LHRH pulse generator is stimulated by naloxone in the pentobarbital-blocked proestrous rat." J.Neuroendocrinol. 7. 917-922 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Funabashi, T.: "The number of luteinizing hormone-releasing hormone immunoreactive neurons is significantly decreased in the forebrain of old-aged female rats." Neurosci.Lett.189. 189. 85-88 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Funabashi, T.: "Fos expression by naloxone in LHRH neurons of the mediobasal bypothalamus and effects of pentobarbital sodium in the proestrous rat." J.Neuroendocrinol. 9. 87-92 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Funabashi, T.: "Bicuculline infusion advances the timing of Fos expression in LHRH neurons in the preoptic area of proestrous rats." NeuroReport. (in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Mitsushima D.: "Possible role of the gamma-amino-butyric acid-A receptor system in the timing of the proestrous luteinizing hormone surge in rats." Endocrinology. (in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-09  

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