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Excessive nerve growth factor impairs bidirectional communication between the oocyte and cumulus cells resulting in reduced oocyte competence.

ABSTRACT: Excessive nerve growth factor (NGF) is commonly found in the follicular fluid of patients with polycystic ovary syndrome (PCOS). Furthermore, oocytes from PCOS patients exhibit lower developmental competence. The purpose of this study was to explore the association between excessive NGF and low oocyte competence in vitro.Excessive NGF was added to mouse cumulus oocyte complexes (COCs) cultured in vitro to investigate meiotic maturation of the oocyte. After culture, mRNA expression levels of Pfkp and Ldha genes in cumulus cells (CCs) and Gdf9, Bmp15 and Fgf8 genes in oocytes, were determined by real-time quantitative polymerase chain reaction (qPCR). We also investigated the mRNA content of Pfkp and Ldha in CCs from PCOS and non-PCOS patients.Excessive NGF significantly inhibited oocyte meiotic maturation. The inhibitory effect was mediated by the NGF high-affinity receptor, NTRK1. mRNA content of Pfkp and Ldha genes in CCs was significantly reduced by excessive NGF stimulation. Moreover, the expression levels of Gdf9, Bmp15 and Fgf8 were also decreased in oocytes, and was induced by excessive NGF-stimulated CCs. In addition, lower expression levels of Pfkp and Ldha in CCs were identified in Chinese PCOS patients with excessive NGF (PCOS, 22?±?2.63 ng/ml, n?=?13; non-PCOS, 7.18?±?2.42 ng/ml, n?=?9; p?

SUBMITTER: Zhai Y

PROVIDER: S-EPMC5869770 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Excessive nerve growth factor impairs bidirectional communication between the oocyte and cumulus cells resulting in reduced oocyte competence.

Zhai Yiwen Y Yao Guidong G Rao Faiza F Wang Yong Y Song Xiaoyuan X Sun Fei F

Reproductive biology and endocrinology : RB&E 20180327 1

<h4>Background</h4>Excessive nerve growth factor (NGF) is commonly found in the follicular fluid of patients with polycystic ovary syndrome (PCOS). Furthermore, oocytes from PCOS patients exhibit lower developmental competence. The purpose of this study was to explore the association between excessive NGF and low oocyte competence in vitro.<h4>Methods</h4>Excessive NGF was added to mouse cumulus oocyte complexes (COCs) cultured in vitro to investigate meiotic maturation of the oocyte. After cult ...[more]

PMID: 29580253

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Project description:Oocyte quality is crucial for subsequent embryo development and so it is a major challenge in assisted reproductive technologies. The aim of the present work was to evaluate the morphometric parameters of oocytes (experiment 1) and the relative gene expression of oocytes and cumulus cells (CCs) (experiment 2) as biomarkers of oocyte quality after individually culturing them (one oocyte or embryo/drop). In experiment 1, individually matured oocytes were measured and classified into small, intermediate, and large oocytes after a cluster analysis, based on total diameter (with zona pellucida, ZP), oocyte diameter (without ZP), and ZP thickness. These oocytes were individually fertilized in vitro and cultured. The embryo development was evaluated up to the blastocyst stage. According to the total diameter, oocyte diameter, and ZP thickness, the blastocyst rate decreased in the small oocytes group (3.1 ± 3.1, 14.1 ± 9.4, and 26.7 ± 3.9, respectively) compared to the intermediate (29.4 ± 5.2, 30.5 ± 10.1, and 28.6 ± 9.6, respectively) and large oocytes groups (54.2 ± 13.5, 44.4 ± 3.9, and 67.6 ± 12.4, respectively). In addition, the probability of reaching the blastocyst stage was positively related to the total diameter (p < 0.001), oocyte diameter (p < 0.05), and ZP thickness (p < 0.001). Furthermore, the relative gene expression of BAX, BCL2, GDF9, and GJA1 was lower in oocytes classified as large. In experiment 2, the mRNA transcript relative abundance pattern of genes in CCs was evaluated according to oocyte total diameter and developmental stage reached. CCs from oocytes classified as large and oocytes capable of developing to the blastocyst stage had a lower relative expression of BAX, STAR, and PTGS2, while a higher expression of HAS2 and SDC2 transcript was observed for those oocytes. In conclusion, oocyte morphometric parameters and gene expression analysis in oocytes and CCs provide methods for the identification of the most competent oocytes for assisted reproductive technologies in sheep.

Project description:Oocyte in vitro maturation can be improved by mimicking the intra-follicular environment. Oocyte, cumulus cells, granulosa cells, and circulating factors act as meiotic regulators in follicles and maintain oocyte in the meiotic phase until oocyte becomes competent and ready to be ovulated. In a randomized experimental design, an ovine model was used to optimize the standard in vitro maturation media by Granulosa secreted factors. At first, the development capacity of oocyte derived from medium (>4 to 6 mm) and small (2 to ≤4 mm) size follicles was determined. Differential gene expression of granulosa secreted factors and their receptors were compared between the cumulus cells of the two groups. Then, the best time and concentration for arresting oocytes at the germinal vesicle stage by natriuretic peptide type C (CNP) were determined by nuclear staining in both groups. Oocyte quality was further confirmed by calcein uptake and gene expression. The developmental competence of cumulus oocyte complexes derived from small size follicles that were cultured in the presence of CNP in combination with amphiregulin (AREG) and prostaglandin E2 (PGE2) for 24 h was determined. Finally, embryo quality was specified by assessing expressions of NANOG, SOX2, CDX2, OCT4, and TET1. The cumulus oocyte complexes derived from small size follicles had a lower capacity to form blastocyst in comparison with cumulus oocyte complexes derived from medium size follicles. Prostaglandin E receptor 2 and prostaglandin-endoperoxide synthase 2 had significantly lower expression in cumulus cells derived from small size follicles in comparison with cumulus cells derived from medium size follicles. Natriuretic peptide type C increased the percentage of cumulus oocyte complexes arresting at the germinal vesicle stage in both oocytes derived from medium and small follicles. Gap junction communication was also improved in the presence of natriuretic peptide type C. In oocytes derived from small size follicles; best blastocyst rates were achieved by sequential exposure of cumulus oocyte complexes in [TCM+CNP (6 h), then cultured in TCM+AREG+PGE2 (18h)] and [TCM+CNP (6 h), then cultured in conventional IVM supplements+AREG+PGE2 (18h)]. Increased SOX2 expression was observed in [TCM+CNP (6 h), then cultured in TCM+AREG+PGE2 (18h)], while decreased OCT4 expression was observed in [TCM+CNP (6 h), then cultured in conventional IVM supplements+AREG+PGE2 (18h)]. It seems that the natriuretic peptide type C modulates meiotic progression, and oocyte development is probably mediated by amphiregulin and prostaglandin E2. These results may provide an alternative IVM method to optimize in vitro embryo production in sheep and subsequently for humans.

Project description:BackgroundIn the cow, lysophosphatidic acid (LPA) acts as an auto-/paracrine factor, through its receptors LPAR1-4, on oocytes and cumulus cells during in vitro maturation (IVM). The aim of the present work was to determine the effect of LPA during IVM of bovine oocytes on: 1) oocyte maturation; 2) apoptosis of COCs; 3) expression of genes involved in developmental competence and apoptosis in bovine oocytes and subsequent blastocysts; 4) cumulus expansion and expression of genes involved in the ovulatory cascade in cumulus cells; 5) glucose metabolism and expression of genes involved in glucose utilization in cumulus cells; 6) cleavage and blastocyst rates on Day 2 and Day 7 of in vitro culture, respectively.MethodsCumulus-oocyte complexes (COCs) were matured in vitro in the presence or absence of LPA (10(-5) M) for 24 h. Following maturation, we determined: oocyte maturation stage, cumulus expansion, COCs apoptosis and glucose and lactate levels in the maturation medium. Moreover, COCs were either used for gene expression analysis or fertilized in vitro. The embryos were cultured until Day 7 to assess cleavage and blastocyst rates. Oocytes, cumulus cells and blastocysts were used for gene expression analysis.ResultsSupplementation of the maturation medium with LPA enhanced oocyte maturation rates and stimulated the expression of developmental competence-related factors (OCT4, SOX2, IGF2R) in oocytes and subsequent blastocysts. Moreover, LPA reduced the occurrence of apoptosis in COCs and promoted an antiapoptotic balance in the transcription of genes involved in apoptosis (BAX and BCL2) either in oocytes or blastocysts. LPA increased glucose uptake by COCs via augmentation of GLUT1 expression in cumulus cells as well as stimulating lactate production via the enhancement of PFKP expression in cumulus cells. LPA did not affect cumulus expansion as visually assessed, however, it stimulated upstream genes of cumulus expansion cascade, AREG and EREG.ConclusionsSupplementation of the maturation medium with LPA improves oocyte maturation rates, decreases extent of apoptosis in COCs and sustains the expression of developmental competence related factors during oocyte maturation and subsequently affects gene expression profile at the blastocyst stage. We also demonstrate that LPA directs glucose metabolism toward the glycolytic pathway during IVM.

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Excessive nerve growth factor impairs bidirectional communication between the oocyte and cumulus cells resulting in reduced oocyte competence.

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Excessive nerve growth factor impairs bidirectional communication between the oocyte and cumulus cells resulting in reduced oocyte competence.

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