Gonadotropin releasing hormone receptor gene and protein expression and immunohistochemical localization in bovine uterus and oviducts

Faculty of Land and Food Systems, The University of British Columbia, 248-2357 Main Mall, Vancouver, BC V6T 1Z4, Canada.
Domestic Animal Endocrinology (Impact Factor: 2.17). 05/2008; 34(3):319-26. DOI: 10.1016/j.domaniend.2007.09.004
Source: PubMed


Recently GnRH, GnRH-R systems has been demonstrated in various extrahypothalamic and extrapituitary reproductive tissues in different mammalian species, where GnRH acts in an autocrine and or paracrine manner and modulates different biological processes. GnRH-R mRNA has also been demonstrated in bovine ovaries (follicle and corpus luteum) and normal and carcinogenic human endometrium/endometrial cells. This is the first study elucidating presence of GnRH-R mRNA and GnRH-R protein in bovine uterus and oviducts in follicular and luteal phases of the estrous cycle and further localizing the receptors to endometrial and oviductal epithelial cells. To our knowledge this is the first report demonstrating GnRH-R mRNA and protein in mammalian oviducts. We used gene-specific primers and monoclonal GnRH-R antibody to test GnRH-R mRNA and GnRH-R protein through RT-PCR and immunobloting. Immunohistochemistry was employed to localize these receptors to endometrial and oviductal epithelial cells. GnRH-R mRNA and receptor protein were expressed at expected molecular weights of 920bp and 60kD, respectively. Densitometry analysis revealed that expression levels for GnRH-R protein in uterus and oviducts were similar to bovine pituitary. The presence of GnRH receptors in bovine uterus and oviducts is intriguing and it would be imperative to examine the functional role of this system in the regulation of reproductive processes.

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    ABSTRACT: The local modulatory role of gonadotropin releasing hormone (GnRH), gonadotropin releasing hormone receptor (GnRH-R) system in regulating steroid hormone receptors at the endometrial level is still not known. Estrogen and progesterone maintain uterine functions by acting through their corresponding receptors; estrogen receptors (ERα and ERβ) and progesterone receptors (PR). We recently demonstrated GnRH-R in bovine endometrium and find the coexistence of GnRH and steroid hormone receptors in endometrium as interesting. Our objective was to determine the effect of a GnRH agonist (buserelin), on the expression of ERα,ERβ, and PR messenger RNA (mRNA) in bovine endometrium. Reproductive tracts were collected from slaughtered cows at a local abattoir, and endometrial explants were treated with buserelin (0, 200, 500, 1000 ng mL-1 respectively), GnRH antagonist-antide (500 ng mL-1) and antide+buserelin (500+ 200 ng mL-1) for 6 h and stored at 80°C for RNA extraction. Two micrograms of total RNA was subjected to reverse transcription polymERαse chain reaction, PCR products electrophoresed (2% agrose gel); visualized and statistically analyzed. The results showed that buserelin (200 ng mL-1) increased the expression of ERα in the luteal phase endometrium. In addition, the expression of endometrial ERα was greater during the follicular than luteal phase. This up regulation of ERα mRNA in luteal phase endometrium suggests that GnRH administration may influence pregnancy in bovines.
    The Canadian veterinary journal. La revue veterinaire canadienne 12/2009; 89(4):467-473. DOI:10.4141/CJAS08120 · 0.52 Impact Factor
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    ABSTRACT: Establishment of the hypothalamic-hypophyseal-gonadal function is dependent on the highly controlled and dynamic interactions between regulatory signals from the brain, pituitary and gonads, all of them leading to the attainment of reproductive capacity, where a coordinated and timely activation of GnRH neurons must occur. The GnRH neurons extend their neurosecretory axons to the hypothalamus where GnRH is released into the pituitary portal vessels to elicit the secretion of LH and FSH, which in turn, will promote gonadal development and support reproductive physiology. Genetic studies have demonstrated that disabling mutations and targeted deletions of the G-protein-coupled receptor (GPR54) generated hypogonadotropic hypogonadism. This link between GPR54 and reproduction, generated attention to the natural ligands of the GPR54 receptor, known as kisspeptins, which are translational products of the hypothalamic gene KiSS1. Recent advances in kisspeptin research have defined a major role of this molecule in controlling the onset of the reproductive function observed at puberty. The aim of this review is to highlight the basic endocrine and genetic concepts involved in the establishment of the hypothalamic-hypophyseal-gonadal axis function which promotes the onset of the reproductive function during puberty. The review highlights what is currently known about the kisspeptin-GPR54 signalling system in the activation of the GnRH neurons.
    Journal of applied biomedicine 01/2010; 8(1):1-9. DOI:10.2478/v10136-009-0001-0 · 1.30 Impact Factor
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