Dynorphin-Kappa Opioid Receptor Signaling Partly Mediates Estrogen Negative Feedback Effect on LH Pulses in Female Rats

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Author(s)

    • MINABE Shiori
    • Laboratory of Reproductive Science, Graduate School of Bioagricultural Sciences, Nagoya University
    • YAMADA Shunji
    • Laboratory of Reproductive Science, Graduate School of Bioagricultural Sciences, Nagoya University
    • UENOYAMA Yoshihisa
    • Laboratory of Reproductive Science, Graduate School of Bioagricultural Sciences, Nagoya University
    • MAEDA Kei-ichiro
    • Laboratory of Animal Breeding, Graduate School of Agricultural and Life Sciences, The University of Tokyo
    • TSUKAMURA Hiroko
    • Laboratory of Reproductive Science, Graduate School of Bioagricultural Sciences, Nagoya University

Abstract

Accumulating evidence suggests that the arcuate nucleus (ARC) kisspeptin/neurokinin B (NKB)/dynorphin (KNDy) neurons play a role in estrogen negative feedback action on pulsatile gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) release. The present study aimed to determine if dynorphin (Dyn) is involved in estrogen negative feedback on pulsatile GnRH/LH release. The effect of the injection of nor-binaltorphimine (nor-BNI), a kappa-opioid receptor (KOR) antagonist, into the third cerebroventricle (3V) on LH pulses was determined in ovariectomized (OVX) adult female rats with/without replacement of negative feedback levels of estradiol (low E<sub>2</sub>). The mean LH concentrations and baseline levels of LH secretion in nor-BNI-injected, low E<sub>2</sub>-treated rats were significantly higher compared with vehicle-treated controls. On the other hand, the nor-BNI treatment failed to affect any LH pulse parameters in OVX rats without low E<sub>2</sub> treatment. These results suggest that Dyn is involved in the estrogen negative feedback regulation of pulsatile GnRH/LH release. The low E<sub>2</sub> treatment had no significant effect on the numbers of ARC <i>Pdyn</i> (Dyn gene)-<i>,</i><i>Kiss1-</i> and <i>Tac2 (</i>NKB gene)-expressing cells. The treatment also did not affect mRNA levels of <i>Pdyn</i> and <i>Oprk1</i> (KOR gene) in the ARC-median eminence region, but significantly increased the ARC kisspeptin immunoreactivity. These findings suggest that the negative feedback level of estrogen suppresses kisspeptin release from the ARC KNDy neurons through an unknown mechanism without affecting the Dyn and KOR expressions in the ARC. Taken together, the present result suggests that Dyn-KOR signaling is a part of estrogen negative feedback action on GnRH/LH pulses by reducing the kisspeptin release in female rats.

Journal

  • Journal of Reproduction and Development

    Journal of Reproduction and Development 59(3), 266-272, 2013-06-01

    THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT

References:  50

Codes

  • NII Article ID (NAID)
    10031184756
  • NII NACSIS-CAT ID (NCID)
    AA10936678
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    09168818
  • NDL Article ID
    024616838
  • NDL Call No.
    Z54-H305
  • Data Source
    CJP  NDL  J-STAGE 
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