| IntroductionOvarian follicular growth is a process involving a complex exchange of hormonal signals between the hypothalamus-pituitary-ovary axis and by a localized para/autocrine mechanism within the ovary involving the oocyte and its adjacent somatic cells. Plenty of studies have been made towards unraveling the complex intraovarian control mechanisms that act in concert with systemic signals to solve some clinical problems, improve the outcome of assisted reproductive technology (ART) and establish the in vitro maturation (IVM) system. Exciting progress has been obtained such as the discovery of oocyte-derived factors; however, there are still many undiscovered mysteries in this field.COH increase the numbers of oocytes ovulated and embryos produced in a variety of mammals. COH has been widely used in ART all over the world. However, artificial induction of ovulation with high doses of gonadotrophins has been demonstrated to decrease the viability of embryos and induce oocyte aneuploidy. Increasing evidences suggest that systemic studies should be conducted to reveal the impact of COH on follicle development and oocyte maturation. Proteomics is the large-scale study of proteins, modifications, complexes and interactions from a given cell line or organism. Proteomics is technically possible to offer detailed information on proteins with differences in protein expression and modification.COH is suspected to influence the maturation of oocytes. Researchers have made great efforts to ameliorate IVF protocols to improve the outcome, such as trying to predicting the maturation and developmental competence of oocytes. The follicular fluid (FF) is the environment of the oocyte during its development and maturation. The composition in FF may influence and/or implicate oocyte quality, and some human follicular fluid proteins have been correlated with oocyte maturation during follicular development. However, no consistent biomarker has been found.The number of acquired oocytes greatly influences the outcome of ART. Poor response to gonadotropin stimulation could not provide enough oocytes for treatment and significantly reduce the likelihood of conceiving in ART. There is accumulating evidence that oocyte plays an important role in regulating the function of neighboring somatic cells during mammalian folliculogenesis. The oocyte was demonstrated to be able to regulate its own maturation and affect the functions of neighboring somatic cells and the ovulation rate. Whether oocyte is associated with the poor response to COH is unknown.In a word, upon the research background mentioned above, we investigate the characteristics of follicle development and oocyte maturation of COH cycle by exploring the proteomics analysis of COH FF, potential markers for oocyte maturation, the mechanism of poor response and to further uncover the intraovarian regulatory mechanisms.Part One: Proteomic Analysis on the Alteration of Follicular Fluid ProteinExpression of Controlled Ovarian HyperstimulationObjective: To study the differences in protein expression of FF of COH cycle andnatural cycle, this is essential to understand the influence of COH on follicledevelopment.Methods: To identify proteins with different expression profiles related to COH, weapplied a proteomic approach and performed two-dimensional gel electrophoresis(2-DE) on six COH FF samples and six FF samples from natural cycle women, followed by comparison of the silver-stained 2-DE profiles.Results: The 2-DE patterns of COH FF and natural cycle FF with good quality havebeen obtained. When compared COH FF and natrual control with PDQuest software,it showed that 2 proteins were down-regulated and 11 proteins were up-regulatedsignificantly (P<0.05) in COH group as determined by spot volume. Among them, 1down-regulated and 7 up-regulated spots were identified by MALDI-TOF MS.Anomalies of several proteins such as, leucine-rich alpha-2-glycoprotein 1,Zn-a2-glycoprotein, transferrin,α1-antitrypsin, human complement component C3had been identified. Changes of haptoglobin, transferrin, human complementcomponent C3 andα1-antitrypsin expressions were further validated in by ratenephelometry analysis and western blot analysis respectively.Conclusion: This study has indicated 8 differential proteins that are associated withovulation, immune response, lipid metabolism in COH FF, leading to a new insightinto the influence of COH on follicle development and oocyte maturation.Part Two: High BMP-15 level in follicular fluid is associated with high qualityoocyte and subsequent embryonic developmentObjective: Bone morphogenetic protein-15 (BMP-15) has displayed influences on oocyte maturation and quality. However, no dependence relation has been established between BMP-15 and oocyte quality/embryonic development in the human. The aim of this study is to investigate the BMP-15 levels in human follicular fluid (FF) and its role in assessing oocyte quality and developmental potential.Methods: A total of seventy-nine occytes and their corresponding FF from 79 women undergoing intracytoplasmic sperm injection (ICSI) were examined. Each recruited oocyte was individually inseminated and thereafter assessed based on their fertilization, cleavage and preimplantation development. BMP-15, FSH, estradiol and progesterone levels of FF were also analysed via the techniques of western blot or radioimmunoassay.Results: Higher FF BMP-15 levels were observed in group fertilization and groupcleavage (P < 0.05). The best embryo morphology had higher BMP-15 levels thanothers (P < 0.01). A significantly positive correlation was found between BMP-15 andestradiol levels in the same follicle.Conclusion: The present study demonstrates that the BMP-15 in FF appears to be apotential factor in predicting oocyte quality and subsequent embryo development, andis regulated by estradiol, which may additionally be a valuable predictor of oocytefertilization.Part Three: Increased BMP-15 and SCF levels in follicular fluid in poorrespondersObjectives: The aim of this study was to investigate the role of oocyte-derived factor bone morphogenetic protein-15 (BMP-15), stem cell factor (SCF) in follicular fluid in the ovarian response to gonadotropin stimulation.Methods: Ninety infertile women undergoing ovarian stimulation with recombinant FSH were recruited. These women were divided into two groups: poor (n=33) and normal responders (n=57). Poor responder was defined as women with...
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