title: The effect of growth hormone (GH) and insulin-like growth factor-I (IGF-I) on in vitro maturation of equine oocytes.
abstract: The objective of this study was to test the hypothesis that equine growth hormone (eGH), in combination with insulin growth factor-I (IGF-I), influences positively in vitro nuclear and cytoplasmic maturation of equine oocytes. Cumulus-oocyte complexes were recovered from follicles that were < 25 mm in diameter, characterized by morphology and were allocated randomly as follow: (a) control (no additives); (b) 400 ng/ml eGH; (c) 200 ng/ml IGF-I; (d) eGH + IGF-I; and (e) eGH + IGF-I + 400 ng/ml anti-IGF-I antibody. Oocytes were matured for 30 h at 38.5°C in air with 5% CO2 and then stained with 10 μg/ml propidium iodide (PI) to evaluate nuclear status and 10 μg/ml Lens culinaris agglutinin-fluorescein complex (FITC-LCA) to assess cortical granule migration by confocal microscopy. The proportion of immature oocytes that developed to the metaphase II (MII) stage in the eGH + IGF-I group (15 of 45) was greater than in the groups that were treated only with IGF-I (7 of 36, p = 0.03). Oocytes that reached MII in the control group (20 of 56; 35.7%) showed a tendency to be different when compared with eGH + IGF-I group (15 of 45; 33.3%, p = 0.08). The treated group that contained anti-IGF-I (15 of 33; 45.4%) decreased the number of oocytes reaching any stage of development when compared with eGH (47 of 72; 65.3%) and eGH + IGF-I (33 of 45; 73.3%) groups (p = 0.05) when data from MI and MII were combined. We concluded that the addition of eGH to in vitro maturation (IVM) medium influenced the in vitro nuclear and cytoplasmic maturation of equine oocytes. The use of GH and IGF-I in vitro may represent a potential alternative for IVM of equine oocytes.
authors.affiliation: Laboratory of Biotechnology and Animal Reproduction-BioRep, Federal University of Santa Maria, Santa Maria, RS, Brazil. gabrielrp@biorep.ufsm.br
authors.forename: Gabriel Ribas
authors.initials: GR
authors.lastname: Pereira
authors.forename: Pedro Luis
authors.initials: PL
authors.lastname: Lorenzo
authors.forename: Gustavo Ferrer
authors.initials: GF
authors.lastname: Carneiro
authors.forename: Barry Allen
authors.initials: BA
authors.lastname: Ball
authors.forename: Paulo Bayard Dias
authors.initials: PB
authors.lastname: Gonçalves
authors.forename: Lígia Maria Cantarelli
authors.initials: LM
authors.lastname: Pegoraro
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bilodeau-Goeseels
authors.forename: John P
authors.initials: JP
authors.lastname: Kastelic
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Casey
authors.forename: Irwin K M
authors.initials: IK
authors.lastname: Liu
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006736:Horses; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone