Endometrial oxytocin receptor and uterine prostaglandin secretion in mares during the oestrous cycle and early pregnancy.
Abstract: Circulating concentrations of 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) were measured before and after administration of oxytocin and after endometrial biopsy, with or without uterine flushing performed per vaginam, on days 10, 14 and 18 after ovulation in nine pregnant and nine cyclic mares. Concentrations of oxytocin receptor were measured in endometrial biopsy samples. Neither pregnancy status nor time after ovulation affected basal PGFM concentrations. PGFM concentrations were increased after oxytocin administration on each of the days studied in cyclic mares; on day 14 the mean response was 4.5 times higher than the mean response on days 10 and 18. In contrast, during pregnancy, responses to oxytocin administration occurred only on days 10 and 18. Marked increases in PGFM concentrations in response to endometrial biopsy occurred only on day 14 in cyclic mares and on day 18 in pregnant mares. Mean concentrations of oxytocin receptor were between 200 and 300 fmol mg-1 protein on day 10 in both pregnant and cyclic mares; in cyclic mares oxytocin receptor concentrations were increased approximately threefold on day 14 compared with days 10 and 18, but no such increase was evident during pregnancy. Total amounts of PGFM secreted after oxytocin treatment correlated with endometrial oxytocin receptor concentrations in cyclic (P 0.5) mares, and the same was true for PGFM release induced by endometrial biopsy (cyclic: P = 0.0025; pregnant: P > 0.5). The data support the hypothesis that endometrial concentrations of oxytocin receptor determine uterine prostaglandin F2 alpha secretion in cyclic mares and that endometrial oxytocin receptor concentrations are reduced in early pregnancy by a product of the conceptus. The increase in response of the pregnant uterus to oxytocin treatment or biopsy-flushing between days 14 and 18 was not due to an increase in the concentration of oxytocin receptors but presumably reflected increased receptor sensitivity.
Publication Date: 1998-12-23 PubMed ID: 9861156DOI: 10.1530/jrf.0.1130173Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The research investigated the relationship between oxytocin receptor concentrations in the uterine lining (endometrium) of mares and their secretion of a specific type of prostaglandin during different stages of their estrous cycle and early pregnancy. The study suggests that the presence of oxytocin receptor in the endometrium impacts the secretion of this prostaglandin in non-pregnant animals. It also indicates a potential reduction of oxytocin receptor concentrations during early pregnancy due to the conceptus (embryo and its associated tissues).
Methodology
- The researchers selected 18 mares for the study, nine of which were pregnant and nine in the cyclic phase.
- They measured the circulating concentrations of 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) before and after administering oxytocin on days 10, 14, and 18 after ovulation.
- They also performed endometrial biopsies with or without uterine flushing.
- The concentrations of oxytocin receptor were then measured from the endometrial biopsy samples.
Results
- The researchers found no impact of either pregnancy status or duration after ovulation on the basal PGFM concentrations.
- In non-pregnant mares, the PGFM levels increased after administering oxytocin on all studied days, with the response on day 14 being significantly higher than on days 10 and 18.
- Contrastingly, in pregnant mares, the responses to oxytocin were restricted to days 10 and 18.
- Sharp increases in PGFM concentrations occurred on day 14 in non-pregnant mares and on day 18 in pregnant mares after performing an endometrial biopsy.
- Oxytocin receptor concentrations were found to be in the range of 200-300 fmol mg-1 protein on day 10, regardless of the pregnancy status.
Interpretation of Results
- On day 14, the concentration of oxytocin receptors increased in the non-pregnant mares, while no increase was observed during pregnancy.
- The total amount of PGFM secreted after oxytocin treatment correlated with the endometrial oxytocin receptor concentrations in non-pregnant mares. This correlation was not observed in pregnant mares.
- The study, therefore, supports the hypothesis that the concentrations of oxytocin receptor in the endometrial lining dictate the secretion of uterine prostaglandin F2 alpha in non-pregnant mares.
- Interestingly, the increase in the pregnant uterus’s response to oxytocin administration or biopsy-flushing between days 14 and 18 was not due to an increase in the oxytocin receptor concentration but likely due to increased receptor sensitivity.
Cite This Article
APA
Starbuck GR, Stout TA, Lamming GE, Allen WR, Flint AP.
(1998).
Endometrial oxytocin receptor and uterine prostaglandin secretion in mares during the oestrous cycle and early pregnancy.
J Reprod Fertil, 113(2), 173-179.
https://doi.org/10.1530/jrf.0.1130173 Publication
Researcher Affiliations
- Department of Physiology and Environmental Science, University of Nottingham, Leicestershire, UK.
MeSH Terms
- Analysis of Variance
- Animals
- Dinoprost / analogs & derivatives
- Dinoprost / blood
- Endometrium / chemistry
- Endometrium / drug effects
- Estrus / physiology
- Female
- Horses / physiology
- Oxytocin / pharmacology
- Pregnancy
- Pregnancy, Animal / physiology
- Progesterone / blood
- Receptors, Oxytocin / analysis
- Time Factors
Citations
This article has been cited 7 times.- Newcombe JR, Cuervo-Arango J, Wilsher S. The Timing of the Maternal Recognition of Pregnancy Is Specific to Individual Mares.. Animals (Basel) 2023 May 22;13(10).
- Lawson EF, Grupen CG, Baker MA, Aitken RJ, Swegen A, Pollard CL, Gibb Z. Conception and early pregnancy in the mare: lipidomics the unexplored frontier.. Reprod Fertil 2022 Jan 1;3(1):R1-R18.
- Klein C, Bruce P, Hammermueller J, Hayes T, Lillie B, Betteridge K. Transcriptional profiling of equine endometrium before, during and after capsule disintegration during normal pregnancy and after oxytocin-induced luteostasis in non-pregnant mares.. PLoS One 2021;16(10):e0257161.
- Swegen A. Maternal recognition of pregnancy in the mare: does it exist and why do we care?. Reproduction 2021 May 5;161(6):R139-R155.
- Gibson C, de Ruijter-Villani M, Bauersachs S, Stout TAE. Asynchronous Embryo Transfer Followed by Comparative Transcriptomic Analysis of Conceptus Membranes and Endometrium Identifies Processes Important to the Establishment of Equine Pregnancy.. Int J Mol Sci 2020 Apr 7;21(7).
- Smits K, Gansemans Y, Tilleman L, Van Nieuwerburgh F, Van De Velde M, Gerits I, Ververs C, Roels K, Govaere J, Peelman L, Deforce D, Van Soom A. Maternal Recognition of Pregnancy in the Horse: Are MicroRNAs the Secret Messengers?. Int J Mol Sci 2020 Jan 9;21(2).
- Smits K, Willems S, Van Steendam K, Van De Velde M, De Lange V, Ververs C, Roels K, Govaere J, Van Nieuwerburgh F, Peelman L, Deforce D, Van Soom A. Proteins involved in embryo-maternal interaction around the signalling of maternal recognition of pregnancy in the horse.. Sci Rep 2018 Mar 27;8(1):5249.
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