RGD Reference Report - Daily GnRH and GnRH-receptor mRNA expression in the ovariectomized and intact rat. - Rat Genome Database

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Daily GnRH and GnRH-receptor mRNA expression in the ovariectomized and intact rat.

Authors: Schirman-Hildesheim, TD  Ben-Aroya, N  Koch, Y 
Citation: Schirman-Hildesheim TD, etal., Mol Cell Endocrinol. 2006 Jun 27;252(1-2):120-5. Epub 2006 May 2.
RGD ID: 1599845
Pubmed: PMID:16672174   (View Abstract at PubMed)
DOI: DOI:10.1016/j.mce.2006.03.010   (Journal Full-text)

We recently described patterns of GnRH and GnRH receptor (GnRH-R) expression in the hypothalamus, pituitary and ovary throughout the rat estrus cycle. Here, we wished to distinguish between regulatory effects of ovarian factors and underlying circadian rhythmicity. We quantified GnRH and GnRH-R mRNA in the pituitary and hypothalamus of long-term ovariectomized (OVX) rats, at different times of day, using real-time PCR. Furthermore, we expanded our previous study of hypothalamic and pituitary GnRH and GnRH-R expression in intact rats by including more time points throughout the estrus cycle. We found different daily patterns of GnRH and GnRH-R expression in intact versus OVX rats, in both tissues. In the hypothalamus of OVX rats, GnRH mRNA peaked at 12, 16 and 20 h, whereas in the hypothalamus of intact rats we observed somewhat higher GnRH mRNA concentrations at 19 h on every day of the estrus cycle except proestrus, when the peak occurred at 17 h. In this tissue, GnRH-R fluctuated less significantly and peaked at 16 h in OVX rats. During the estrus cycle, we observed higher levels in the afternoon of each day except on estrus. In OVX rats, pituitary GnRH mRNA rose sharply at 9 h, with low levels thereafter. In these animals, pituitary GnRH-R also peaked at 9h followed by a second rise at 22 h. In intact rats pituitary GnRH was high at noon of diestrus-II and on estrus, whereas GnRH-R mRNA was highest in the evening of diestrus-II. This is the first demonstration of daily GnRH and GnRH-R mRNA expression patterns in castrated animals. The observed daily fluctuations hint at underlying tissue-specific circadian rhythms. Ovarian factors probably modulate these rhythms, yielding the observed estrus cycle patterns.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Gnrh1Ratovulation cycle  IEP  RGD 

Objects Annotated

Genes (Rattus norvegicus)
Gnrh1  (gonadotropin releasing hormone 1)


Additional Information