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Ovarian response in sheep superovulated after pretreatment with growth hormone and GnRH antagonists is weakened by failures in oocyte maturation

Published online by Cambridge University Press:  04 February 2005

Pedro Gonzalez-Añover
Affiliation:
Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain. Cátedra de Farmacología, Facultad de Veterinaria, UCM, Avda. Puerta de Hierro Km. 5.6, 28040 Madrid, Spain.
Teresa Encinas
Affiliation:
Cátedra de Farmacología, Facultad de Veterinaria, UCM, Avda. Puerta de Hierro Km. 5.6, 28040 Madrid, Spain.
Rosa M. Garcia-Garcia
Affiliation:
Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain. Current address: Departamento de Ciencia y Tecnología Agroforestal, EUITA-UCLM, Ciudad Real, Spain.
Almudena Veiga-Lopez
Affiliation:
Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain.
Maria J. Cocero
Affiliation:
Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain.
Alan S. McNeilly
Affiliation:
MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, University of Edinburgh Chancellor's Building, Little France Crescent, Edinburgh EH16 4SB, UK.
Antonio Gonzalez-Bulnes
Affiliation:
Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain.

Abstract

The administration of growth hormone (GH) or GH plus GnRH antagonists (GnRHa) in sheep allows the enhancement of the pool of gonadotrophin-responsive follicles present in the ovaries and may be useful to increase yields obtained in embryo programmes. The objective of the current study was to evaluate the ability of follicles recruited in response to treatment with GH and GnRHa to grow in response to exogenous follicle stimulating hormone (FSH) and the competence of their oocytes to resume meiosis. Seven females were treated with two doses of GnRHa (days 0 and 3) and three doses of 15 mg of GH (days 3, 4 and 5). Thereafter, this group and a second group (n=7) were treated with three doses of 1.5 ml of FSH 12 h apart. A third group (control; n=4) did not receive GH/GnRHa or FSH. The mean number of follicles aspirated on day 7 was higher in ewes treated with GH and GnRHa prior to the stimulation with exogenous FSH than in ewes treated with FSH without pretreatment and in untreated control sheep (20.4 ± 2.6 vs 17.7 ± 3.9 and 11.5 ± 0.8, p < 0.05 and p < 0.01, respectively). The number of recovered cumulus–oocyte complexes after follicular aspiration was higher in the GH/GnRHa+FSH group (8.7 ± 0.9 vs 6.8 ± 1.3 in FSH group, n.s., and 4.5 ± 0.8 in control, p < 0.05), but there were no differences found in the resumption of meiosis (63.1 ± 9.5% for GH/GnRHa + FSH vs 79.5 ± 6.3% for FSH and 60.0 ± 8.8% for control). These results indicate that GH and GnRHa would be useful to increase the number of gonadotrophin-responsive follicles in the ovary, but adjustment of later FSH treatment allowing further development of follicles may be necessary prior to its use in superovulatory protocols.

Type
Research Article
Copyright
2004 Cambridge University Press

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