The effect of growth hormone (GH) and insulin-like growth factor-I (IGF-I) on in vitro maturation of equine oocytes

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...

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Bibliographic Details
Published in:	Zygote (Cambridge) Vol. 20; no. 4; p. 353
Main Authors:	Pereira, Gabriel Ribas, Lorenzo, Pedro Luis, Carneiro, Gustavo Ferrer, Ball, Barry Allen, Gonçalves, Paulo Bayard Dias, Pegoraro, Lígia Maria Cantarelli, Bilodeau-Goeseels, Sylvie, Kastelic, John P, Casey, Patrick J, Liu, Irwin K M
Format:	Journal Article
Language:	English
Published:	England 01-11-2012
Subjects:	Animals Cell Nucleus - drug effects Female Growth Hormone - pharmacology Horses Insulin-Like Growth Factor I - pharmacology Microscopy, Confocal Oocytes - cytology Oocytes - drug effects Oocytes - metabolism Ovarian Follicle - cytology Ovarian Follicle - drug effects Ovarian Follicle - metabolism
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Summary:	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.
ISSN:	1469-8730
DOI:	10.1017/S0967199411000335