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Zygote

Table of Contents - 2004 - Volume 12, Issue 04  


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

Pedro Gonzalez-Añover a1a2, Teresa Encinas a2, Rosa M. Garcia-Garcia a1p1, Almudena Veiga-Lopez a1, Maria J. Cocero a1, Alan S. McNeilly a3 and Antonio Gonzalez-Bulnes a1c1
a1 Departamento de Reproduccion Animal INIA, Avda. Puerta de Hierro Km. 5.9, 28040 Madrid, Spain.
a2 Cátedra de Farmacología, Facultad de Veterinaria, UCM, Avda. Puerta de Hierro Km. 5.6, 28040 Madrid, Spain.
a3 MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, University of Edinburgh Chancellor's Building, Little France Crescent, Edinburgh EH16 4SB, UK.

Article author query
gonzalez-anover p   [PubMed][Google Scholar] 
encinas t   [PubMed][Google Scholar] 
garcia-garcia r   [PubMed][Google Scholar] 
veiga-lopez a   [PubMed][Google Scholar] 
cocero mj   [PubMed][Google Scholar] 
mcneilly as   [PubMed][Google Scholar] 
gonzalez-bulnes a   [PubMed][Google Scholar] 

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.

(Received July 9 2004)
(Accepted September 21 2004)


Key Words: Follicle; GnRH analogues; Growth hormone; Oocyte; Sheep.

Correspondence:
c1 All correspondence to: Antonio Gonzalez-Bulnes, Departamento Reproducción Animal INIA, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain. Tel: +34 91 347 4022. Fax: +34 91 347 4014. e-mail: bulnes@inia.es
p1 Current address: Departamento de Ciencia y Tecnología Agroforestal, EUITA-UCLM, Ciudad Real, Spain.

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