Document Detail

Alterations in RFamide-related peptide expression are coordinated with the preovulatory luteinizing hormone surge.
MedLine Citation:
PMID:  18566114     Owner:  NLM     Status:  MEDLINE    
The preovulatory LH surge is triggered when the circadian pacemaker, the bilateral suprachiasmatic nucleus (SCN), stimulates the GnRH system in the presence of high estrogen concentrations (positive feedback). Importantly, during the remainder of the estrous cycle, estradiol inhibits LH release via negative feedback. We have recently documented the presence of a novel mammalian RFamide-related peptide (RFRP), a putative gonadotropin-inhibitory hormone (GnIH), that presumably acts upstream of GnRH to modulate the negative feedback effects of estrogen. The present series of studies used female Syrian hamsters to examine the possibility that, in addition to driving the LH surge positively, the SCN concomitantly coordinates the removal of steroid-mediated RFRP inhibition of the gonadotropic axis to permit the surge. We found that the SCN forms close appositions with RFRP cells, suggesting the possibility for direct temporal control of RFRP activity. During the time of the LH surge, immediate-early gene expression is reduced in RFRP cells, and this temporal regulation is estrogen dependent. To determine whether projections from the SCN regulate the timed reduction in activation of the RFRP system, we exploited the phenomenon of splitting. In split animals in which the SCN are active in antiphase, activation of the RFRP system is asymmetrical. Importantly, this asymmetry is opposite to the state of the GnRH system. Together, these findings point to novel circadian control of the RFRP system and potential participation in the circuitry controlling ovulatory function.
Erin M Gibson; Stephanie A Humber; Sachi Jain; Wilbur P Williams; Sheng Zhao; George E Bentley; Kazuyoshi Tsutsui; Lance J Kriegsfeld
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2008-06-19
Journal Detail:
Title:  Endocrinology     Volume:  149     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-23     Completed Date:  2008-11-04     Revised Date:  2013-03-27    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4958-69     Citation Subset:  AIM; IM    
Department of Psychology and Helen Wills Neuroscience Institute, 3210 Tolman Hall, 1650, University of California, Berkeley, California 94720-1650, USA.
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MeSH Terms
Circadian Rhythm / physiology*
Dorsomedial Hypothalamic Nucleus / cytology,  physiology
Estrogens / metabolism,  pharmacology
Follicular Phase / physiology*
Gonadotropin-Releasing Hormone / metabolism
Luteinizing Hormone / metabolism*
Median Eminence / cytology,  physiology
Microscopy, Fluorescence
Neural Pathways
Neuropeptides / metabolism*
Pituitary Gland / cytology,  physiology
Suprachiasmatic Nucleus / cytology,  physiology
Grant Support
Reg. No./Substance:
0/Estrogens; 0/Neuropeptides; 0/RFamide peptide; 33515-09-2/Gonadotropin-Releasing Hormone; 9002-67-9/Luteinizing Hormone

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