Luteal stage dependence of pituitary response to gonadotrophin-releasing hormone in cyclic dairy ewes subjected to synchronisation of ovulation
G. S. Amiridis A F , I. Valasi A , I. Menegatos B , C. Rekkas C , P. Goulas D , T. Papanikolaou A and C. Deligiannis EA Department of Reproduction and Obstetrics, Veterinary Faculty, University of Thessaly, PO Box 199, 43100 Karditsa, Greece.
B Department of Anatomy and Physiology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece.
C National Agricultural Research Foundation Veterinary Research Institute, 57008 Ionia Thessaloniki, Greece.
D Department of Animal Production Technological Institution of Larissa, 41110 Larissa, Greece.
E National Agricultural Research Foundation Agricultural Research Station of Palama, 43200 Palamas, Karditsa, Greece.
F Corresponding author. Email: gsamir@vet.uth.gr
Reproduction, Fertility and Development 17(8) 769-774 https://doi.org/10.1071/RD05068
Submitted: 22 June 2005 Accepted: 25 September 2005 Published: 30 November 2005
Abstract
Possible hormonal aberrations precluding conception or maintenance of pregnancy in dairy ewes subjected to ovulation synchronisation were investigated in this study. The pituitary response to exogenous gonadotrophin-releasing hormone (GnRH) was tested at different luteal stages in 36 ewes. Oestruses were synchronised by using progestagen-impregnated sponges and the animals were randomly allotted into one of three treatment groups (A, B and C; n = 12 for each). Treatments commenced on Days 4, 9 and 14 of the new cycle (oestrus was defined as Day 0). Ewes were given two GnRH injections, 5 days before and 36 h after a prostaglandin F2α (PGF2α) injection, and the animals were inseminated 12–14 h after the second GnRH injection (modified OVSYNCH). For luteinising hormone (LH) determination blood samples were withdrawn from six ewes of each group at the time of GnRH administration, and 30, 90, 180, 270 and 360 min later. Progesterone was assayed in samples taken every other day starting from oestrus and for 17 days after the second GnRH injection, and in an additional sample collected on the day of insemination. After the first GnRH injection, the LH concentration was higher in Group C than in Groups B and A (mean ± s.d.: 64.8 ± 10.0 ng mL−1, 41.3 ± 3.7 ng mL−1 and 24.6 ± 9.0 ng mL−1, respectively; P < 0.05), whereas after the second GnRH injection a uniform LH release was found in all groups. PGF2α caused a significant decrease in progesterone (P4) concentration in all groups; however, at artificial insemination ewes that conceived had significantly lower P4 concentration in comparison with those that failed to conceive. As early as Day 5, pregnant animals had higher P4 concentrations than non-pregnant animals. Overall, 21 animals conceived (seven, nine and five ewes from Groups A, B and C, respectively). These results indicate that the proposed protocol is equally effective in inducing a preovulatory LH surge at any stage of the luteal phase, and that elevated P4 concentration along with a delayed P4 increase should be considered as a causative factor for inability to conceive.
Extra keywords: luteinising hormone, progesterone, sheep, timed insemination.
Acknowledgments
Financial support for this work was provided by the PENED 2001 project (project code 01EΔ280; contributors: European Union, General Secretariat of Research and Technology of Greece, and the Dairy Industry FAGE SA). Ms I. Valasi is subsidised by the same project.
Acritopoulou, S. , and Haresign, W. (1980). Response of ewes to a single injection of an analogue of PGF2α given at different stages of the oestrous cycle. J. Reprod. Fertil. 58, 219–221.
| PubMed |
Karsh, F. J. , Foster, D. L. , Legan, S. J. , Ryan, K. D. , and Peter, G. K. (1979). Control of the preovulatory endocrine events in the ewe: interrelationship of estradiol, progesterone and luteinising hormone. Endocrinology 105, 421–426.
| PubMed |
Karsch, F. J. , Cummins, J. T. , Thomas, G. B. , and Clarke, I. J. (1987). Steroid feedback inhibition of pulsatile secretion of gonadotropin releasing hormone in the ewe. Biol. Reprod. 36, 1207–1218.
| PubMed |
Langford, G. A. , Ainsworth, L. , and Wolynetz, M. S. (1982). Reproductive response of progesterone treated sheep in confinement to a single and double insemination. J. Anim. Sci. 54, 12–17.
| PubMed |
Legan, S. J. , l’Anson, H. , Fitzgerald, B. P. , and Akaydin, M. S. (1985). Importance of short luteal phases in the endocrine mechanisms controlling initiation of estrous cycles in anestrous ewes. Endocrinology 117, 1530–1536.
| PubMed |
Lund, S. A. , Murdoch, J. , vanKirk, E. A. , and Murdoch, W. J. (1999). Mitogenic and antioxidant mechanisms of estradiol action in preovulatory ovine follicles: relevance to luteal function. Biol. Reprod. 61, 388–392.
| PubMed |
Lymberopoulos, A. , Amirids, G. S. , Kuehholzer, B. , Besenfelder, U. , Christodoulou, V. , Vainas, E. , and Brem, G. (2001). Fertilization and embryo recovery rates in superovulated Chios ewes following laparoscopic intrauterine insemination. Theriogenology 55, 1855–1862.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
McLeod, B. J. , Haresigh, B. , and Lamming, G. E. (1982). The induction of ovulation and luteal function in seasonally anestrous ewes treated with small dose multiple injections of GnRH. J. Reprod. Fertil. 65, 215–221.
| PubMed |
McNatty, K. P. , Hudson, N. L. , Ball, K. , and Forbes, S. (1988). Treatment of seasonally anestrous Romney ewes with continuous infusion of low doses of GnRH: effects on estrus, ovulation and plasma progesterone concentration. Theriogenology 30, 953–960.
McNeilly, A. S. , Hunter, M. , Land, R. B. , and Fraser, H. M. (1981). Inadequate corpus luteum function after the induction of ovulation in anoestrous ewes by LH-RH or LH-RH agonist. J. Reprod. Fertil. 63, 137–144.
| PubMed |
Menegatos, J. , Chadio, S. , Kalogiannis, T. , Kouskoura, T. , and Kouimtzis, S. (2003). Endocrine events during the periestrous period and the subsequent estrous cycle in ewes after estrus synchronization. Theriogenology 59, 1533–1543.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Murdoch, W. J. , and van Kirk, E. A. (1998). Luteal dysfunction in ewes induced to ovulate early in follicular phase. Endocrinology 139, 3480–3484.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Ravindra, J. P. , Rawlings, N. C. , Evans, A. C. O. , and Adams, G. P. (1994). Ultrasonographic study of ovarian follicular dynamics in ewes during the oestrous cycle. J. Reprod. Fertil. 101, 501–509.
| PubMed |
Rawlings, N. C. , Jeffcoate, I. A. , and Rieger, D. L. (1984). The influence of estradiol 17β and progesterone on peripheral serum concentrations of luteinizing hormone and follicle stimulating hormone in the ovariectomized ewe. Theriogenology 22, 473–488.
| Crossref | GoogleScholarGoogle Scholar |
Rubianes, E. , Beard, A. , Dierschke, D. J. , Bartlewski, P. , Adams, G. P. , and Rawlings, N. (1997). Endocrine and ultrasound evaluation of the response to PGF2α and GnRH given at different stages of the luteal phase in cyclic ewes. Theriogenology 48, 1093–1104.
| Crossref | GoogleScholarGoogle Scholar |
Rubianes, E. , Menchaca, A. , and Carbajal, B. (2003). Response of the 1–5 day-aged ovine corpus luteum to prostaglandin F2α. Anim. Reprod. Sci. 78, 47–55.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Skinner, D. C. , Evans, N. P. , Delaleu, B. , Goodman, R. L. , Bouchard, P. , and Caraty, A. (1999). The negative feedback actions of progesterone on gonadotropin releasing hormone secretion are transduced by the classical progesterone receptor. Proc. Natl Acad. Sci. USA 95, 10 978–10 983.
| Crossref | GoogleScholarGoogle Scholar |
Taragnat, C. , Bernier, A. , and Fontaine, J. (1998). Gonadotrophin storage patterns in the ewe during the oestrous cycle or after long-term treatment with a GnRH agonist. J. Endocrinol. 156, 149–157.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Theodosiadou, E. , Goulas, P. , Kouskoura, T. , and Smokovitis, A. (2004). Oestrogen and progesterone concentrations in plasma and oviductal tissue of ewes exhibiting a natural or induced oestrus. Anim. Reprod. Sci. 80, 59–67.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Wathes, D. C. (1992). Embryonic mortality and the uterine environment. J. Endocrinol. 134, 321–325.
| PubMed |
Xiao, E. , Xia-Zhang, L. , and Ferin, M. (2002). Inadequate luteal function is the initial clinical cyclic defect in a 12 day stress model that includes a psychogenic component in the Rhesus monkey. J. Clin. Endocrinol. Metab. 87, 2232–2237.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
