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  • Author: Paulo Bayard D Gonçalves x
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Marcos H Barreta Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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João Francisco C Oliveira Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Rogério Ferreira Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Alfredo Q Antoniazzi Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Bernardo G Gasperin Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Luciano R Sandri Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Paulo Bayard D Gonçalves Laboratory of Biotechnology and Animal Reproduction, BioRep, Federal University of Santa Maria, 97105-900 Santa Maria, RS, Brazil

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Angiotensin II (AngII) prevents the inhibitory effect of follicular cells on oocyte maturation, but its involvement in LH-induced meiotic resumption remains unknown. The aim of this study was to assess the involvement of AngII in LH-induced meiotic resumption and of prostaglandins (PGs) in the action of AngII. In the experiment I, seven cows were superovulated, intrafollicularly injected with 10 μM saralasin (a competitive AngII antagonist) or saline when the follicles reached a diameter larger than 12 mm, and challenged with a GnRH agonist to induce an LH surge. Fifteen hours after GnRH, the animals were ovariectomized and the oocytes were recovered to determine the stage of meiosis. The oocytes from follicles that received saline were in germinal vesicle (GV) breakdown (30.8%) or metaphase I (MI; 69.2%) stage while those that received saralasin were in the GV stage (100%; P<0.001) 15 h after GnRH agonist. In another experiment, oocytes were co-cultured with follicular hemisections for 15 h to determine whether PGs mediate the effect of AngII on meiotic resumption. Indomethacin (10 μM) inhibited AngII-induced meiotic resumption (13.4 vs 77.5% MI without indomethacin; P<0.001). Furthermore, the GV oocytes progressed to MI at a similar rate when PGE2, PGF or AngII was present in the co-culture system with follicular cells (PGE2 77.4%, PGF 70.0%, and AngII 75.0% MI). In conclusion, our results provide strong evidence that AngII mediates the resumption of meiosis induced by an LH surge in bovine oocytes and that this event is dependent on PGE2 or PGF produced by follicular cells.

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Bernardo G Gasperin
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Rogério Ferreira Laboratory of Biotechnology and Animal Reproduction, Department of Animal Science, Department of Physiology, Animal Reproduction Research Centre, BioRep, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil

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Monique T Rovani
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Joabel T Santos
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José Buratini Laboratory of Biotechnology and Animal Reproduction, Department of Animal Science, Department of Physiology, Animal Reproduction Research Centre, BioRep, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil

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Christopher A Price Laboratory of Biotechnology and Animal Reproduction, Department of Animal Science, Department of Physiology, Animal Reproduction Research Centre, BioRep, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil

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Paulo Bayard D Gonçalves
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Fibroblast growth factors (FGFs) are involved in paracrine control of follicle development. It was previously demonstrated that FGF10 decreases estradiol (E2) secretion in granulosa cell culture and that theca cell FGF10 mRNA expression is decreased in healthy follicles from abattoir ovaries. The main objectives of this study were to evaluate FGF10 and FGFR2b mRNA expression during follicular development in vivo, to evaluate the effect of FGF10 on follicle growth using Bos taurus taurus cows as a model, and to gain more insight into the mechanisms through which FGF10 inhibits steroidogenesis. Messenger RNA encoding both FGF10 and FGFR2b (main FGF10 receptor) was significantly more expressed in subordinate follicles (SFs) than in dominant follicles (DFs). The intrafollicular injection of FGF10 into the largest growing follicle at 7–8 mm in diameter interrupted the DF growth in a dose-dependent manner (11±0.4, 8.3±1 and 5.9±0.3 mm for 0, 0.1, and 1 μg/ml FGF10, respectively, at 72 h after treatment; P<0.05). In a third experiment, follicles were obtained 24 h after FGF10 (1 μg/ml) or PBS treatment through ovariectomy. In theca cells, FGF10 treatment did not affect mRNA encoding steroidogenic enzymes, LHCGR and IGFBPs, but significantly upregulated FGF10 mRNA expression. The expression of CYP19A1 mRNA in granulosa cells was downregulated by FGF10 treatment, which was accompanied by a 50-fold decrease in E2 production, and decreased cyclin D2 mRNA. These results have shown that FGF10 and its receptor FGFR2b are more expressed in SFs and provide solid in vivo evidence that FGF10 acts as an important regulator of follicular growth in cattle.

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Matheus P. De Cesaro M De Cesaro, Laboratory of Biotechnology and Animal Reproduction , Federal University of Santa Maria, Santa Maria, Brazil

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Mariana P de Macedo M de Macedo, Department of Animal Science, McGill University, Montreal, Canada

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Paulo R A da Rosa P da Rosa, Laboratory of Biotechnology and Animal Reproduction, Federal University of Santa Maria, Santa Maria, Brazil

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Joabel T dos Santos J dos Santos, Laboratory of Biotechnology and Animal Reproduction, Federal University of Santa Maria, Santa Maria, Brazil

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Ricardo D. Mea R Mea, Laboratory of Biotechnology and Animal Reproduction , Federal University of Santa Maria, Santa Maria, Brazil

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Janduí E. da Nóbrega Jr. J da Nóbrega Jr., Laboratory of Biotechnology and Animal Reproduction , Federal University of Santa Maria, Santa Maria, Brazil

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Raj Duggavathi R Duggavathi, Animal Science, McGill University Faculty of Agricultural and Environmental Sciences, Sainte-Anne-de-Bellevue, Canada

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Bernardo G Gasperin B Gasperin, Laboratory of Biotechnology and Animal Reproduction, Federal University of Pelotas, Pelotas, Brazil

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Paulo Bayard D Gonçalves P Gonçalves, Laboratory of Biotechnology and Animal Reproduction , Federal University of Santa Maria, Santa Maria, Brazil

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Vilceu Bordignon V Bordignon, Department of Animal Science, McGill University, Montreal, Canada

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The significant role of C-type natriuretic peptide (CNP) and its receptor 2 (NPR2) in regulating oocyte meiotic maturation and facilitating communication between oocytes and surrounding cumulus cells has been well-documented in various mammalian species, including mice, cattle and swine. However, further investigation is needed to ascertain whether natriuretic peptide receptors (NPRs) are involved in regulating other essential ovarian functions. Hence, this study aimed to explore the potential involvement of NPRs in the regulation of cumulus expansion and oocyte meiotic maturation in bovine cumulus-oocyte complexes (COCs). The findings revealed that NPR3 mRNA abundance was downregulated by FSH and LH in cumulus cells of bovine COCs during in vitro maturation (IVM), while NPR2 mRNA levels were not affected by gonadotropins. Inhibition of the epidermal growth factor receptor (EGFR) during IVM of COCs prevented the NPR3 mRNA downregulation induced by gonadotropins in cumulus cells. Additionally, treatment of COCs during IVM with an NPR3 agonist (cANP4-23) inhibited cumulus expansion induced by gonadotropins. This inhibitory effect was further intensified when COCs were co-treated with cANP4-23 and CNP. These findings provide robust evidence indicating that normal cumulus expansion in bovine COCs involves an inhibitory effect of gonadotropins on NPR3 mRNA expression, which is mediated via EGFR signaling. The study also provides evidence that CNP and NPR3 interact synergistically to regulate cumulus expansion in response to gonadotropins.

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