title: Gene expression analysis of bovine oocytes at optimal coasting time combined with GnRH antagonist during the no-FSH period.
abstract: Ovarian stimulation with FSH combined with an appropriate period of FSH withdrawal (coasting) before ovum pick-up now appears to be a successful way to obtain oocytes with high developmental competence in bovine. Recent results showed that extending follicular growth by only 24 hours has a detrimental effect on oocyte quality as shown by the reduced blastocyst formation rate. Although these treatments are initiated during the luteal phase with low LH level, the small LH pulsatility present at that time could potentially impact follicular development as well as oocyte quality. In this study, a GnRH antagonist (Cetrotide) was used to suppress LH secretion during follicular differentiation to get a better insight into the physiological importance of the LH support during that period. Oocytes were collected by ovum pick-up, and quality was assessed by measuring the blastocyst formation rate obtained after IVM-IVF. The oocyte transcriptome from GnRH antagonist-treated animals was also compared with that from a control group (coasting duration of 68 hours) to detect possible alterations at the messenger RNA (mRNA) level. The oocyte quality was not statistically affected by the treatment as shown by the blastocyst formation rate obtained. However, microarray analysis showed that a total of 226 genes had a significant difference (fold change > 2; P < 0.05) at the mRNA level, with the majority being in overabundance in the treated group. Many genes related to RNA posttranscriptional modifications presented different abundance at the mRNA level significant differences in the control group (68 hours), whereas translation function appeared to be affected, with many genes related to structural constituents of the ribosome presenting a overabundance in the GnRH antagonist-treated group. Specific mRNAs with crucial roles in chromosome segregation control also showed significant difference at the mRNA level after Cetrotide treatment. The results presented here indicated that the suppression of the LH secretion in an optimal stimulated context would have an impact on the oocyte, with the possible alteration of critical functions related to translation capacity and chromosome segregation control.
authors.affiliation: Centre de recherche en biologie de la reproduction, Faculté des sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Pavillon INAF, Université Laval, Quebec, Québec, Canada.
authors.forename: Rémi
authors.initials: R
authors.lastname: Labrecque
authors.affiliation: L'Alliance Boviteq, Saint-Hyacinthe, Québec, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Vigneault
authors.affiliation: L'Alliance Boviteq, Saint-Hyacinthe, Québec, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Blondin
authors.affiliation: Centre de recherche en biologie de la reproduction, Faculté des sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Pavillon INAF, Université Laval, Quebec, Québec, Canada. Electronic address: Marc-Andre.Sirard@fsaa.ulaval.ca.
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Sirard
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors*; D007986:Luteinizing Hormone / Q000378:metabolism; D046228:Microarray Analysis; D009865:Oocytes / Q000737:chemistry* / Q000254:growth & development; D012333:RNA, Messenger / Q000032:analysis; D013997:Time Factors; D059467:Transcriptome
chemical_list: D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C062876:cetrorelix
keywords: Bovine; Cetrotide; GnRH antagonist; LH; Oocyte quality; Transcriptome