title: Hormonal and molecular characterization of follicular fluid, cumulus cells and oocytes from pre-ovulatory follicles in stimulated and unstimulated cycles.
abstract: BACKGROUND
  The use of ovarian stimulation, to stimulate a multi-follicular response for assisted reproduction treatments, may force the production of oocytes from follicles that do not reach optimal maturation, possibly yielding oocytes that are not fully competent. The present study aimed to define the follicular environment and oocyte competence of unstimulated pre-ovulatory follicles, to compare it with that of similar-sized stimulated follicles. For this purpose, we analyzed the follicular hormonal milieu, the oocyte meiotic spindle, the embryo development and the cumulus cells gene expression (GE) profiles.
  
  
  RESULTS
  The study population was divided in two groups: (i) 42 oocyte donors undergoing unstimulated cycles and (ii) 18 oocyte donors undergoing controlled ovarian stimulation cycles (COS). Follicular fluid was analyzed to quantify the concentrations of estradiol (E2), progesterone (P), FSH, LH, testosterone (T) and androstendione (Δ4). T was higher in the COS group, while Δ4, E2 and LH were significantly higher in unstimulated cycles. The cumulus oophorus cells (CC) surrounding the oocyte were removed and their GE profiles were analyzed with microarrays. There were 18 differentially expressed genes in CC: 7 were up-regulated and 11 were down-regulated in the COS cycles. The microarray was validated by qRT-PCR. The analysis of spindle structure revealed no significant differences between the groups, except for the parameter of length which presented differences. The fertilization ability and embryo morphology on Days 2, 3 and 4 did not show any significant differences between groups.
  
  
  CONCLUSIONS
  The use of ovarian stimulation induces changes in the follicular fluid and in CC GE that may affect immune processes, meiosis and ovulation pathways. Although these differences do not seem to relate to early-stage embryo morphology, the implications of some of the molecules, especially ALDH1A2, CTSL and ZNF33B at the CC level, deserve to be addressed in future studies.
authors.affiliation: Instituto Universitario IVI Valencia, Plaza de la Policía Local, Valencia, Spain. mariajose.delossantos@ivi.es
authors.forename: Maria José
authors.initials: MJ
authors.lastname: de los Santos
authors.forename: Virginia
authors.initials: V
authors.lastname: García-Láez
authors.forename: Diana
authors.initials: D
authors.lastname: Beltrán-Torregrosa
authors.forename: José A
authors.initials: JA
authors.lastname: Horcajadas
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Martínez-Conejero
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Esteban
authors.forename: Antonio
authors.initials: A
authors.lastname: Pellicer
authors.forename: Elena
authors.initials: E
authors.lastname: Labarta
mesh_terms: D000328:Adult; D000735:Androstenedione / Q000032:analysis; D054885:Cumulus Cells / Q000737:chemistry / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology; D004958:Estradiol / Q000032:analysis; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis; D015571:Follicular Fluid / Q000737:chemistry*; D015870:Gene Expression; D006728:Hormones / Q000032:analysis*; D006801:Humans; D007986:Luteinizing Hormone / Q000032:analysis; D008540:Meiosis; D046228:Microarray Analysis; D009865:Oocytes / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D006080:Ovarian Follicle / Q000502:physiology; D010062:Ovulation Induction / Q000009:adverse effects*; D011374:Progesterone / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020554:Sperm Injections, Intracytoplasmic; D013739:Testosterone / Q000032:analysis
chemical_list: D006728:Hormones; D012333:RNA, Messenger; D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone