Changes in equine endometrial oestrogen receptor alpha and progesterone receptor mRNAs during the oestrous cycle, early pregnancy and after treatment with exogenous steroids.
Abstract: Two experiments were performed to determine changes in the abundance of oestrogen and progesterone receptor (ER alpha and PR) mRNAs in equine endometrium during the oestrous cycle and early pregnancy, and under the influence of exogenous steroids. In Expt 1, endometrial biopsies were obtained from non-mated mares during oestrus and at days 5, 10 and 15 after ovulation, and from pregnant mares at days 10, 15 and 20 after ovulation. There were overall effects of day on the abundance of ER alpha (P = 0.0001) and PR (P = 0.0014) mRNAs. The amount of ER alpha mRNA decreased at day 10 of pregnancy, and PR mRNA was reduced at day 5 in non-mated mares and at day 15 of pregnancy, compared with oestrous values. Experiment 2 was conducted to determine the effects of exogenous steroids on endometrial ER alpha and PR mRNAs. Endometrial biopsies were obtained from 19 anoestrous mares that had been treated with vehicle, oestradiol, progesterone, or oestradiol followed by progesterone for either a short or a long duration. The steroid treatment affected the abundance of ER alpha mRNA (P = 0.0420), which was higher (P < 0.05) in the oestradiol group than in the group treated with oestradiol followed by long duration progesterone. The steroid treatment did not affect the abundance of PR mRNA. These results demonstrate that the amount of steroid receptor mRNA changes with the fluctuating steroid environment in the uterine endometrium of cyclic and early pregnant mares, and that the duration of progesterone dominance may affect ER alpha gene expression. In addition, factors other than steroids may regulate ER alpha and PR gene expression in equine uterine endometrium.
Publication Date: 2000-01-25 PubMed ID: 10645254DOI: 10.1530/jrf.0.1170135Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study focuses on the changes in estrogen and progesterone receptor mRNAs in the uterine lining of horses, and how these changes are influenced by the reproductive cycle, early stages of pregnancy, and treatment with external hormones. Notably, it reveals that the amount of these mRNAs varies in correlation with the hormone environment in the uterus, and that this mechanism can be affected by the duration of progesterone dominance.
Study Overview
- The research consists of two separate experiments, with common focus on changes in mRNA of estrogen and progesterone receptors (ER alpha and PR).
- The subject matter was centered around the equine endometrium – the inner lining of a mare’s uterus.
- The driving factor behind the research included hormonal changes throughout the oestrus cycle, early stages of pregnancy, and the impact of externally administered steroids.
Experiment 1
- Biopsies were taken from non-mated mares in heat and 5, 10, and 15 days after ovulation. In pregnant mares, samples were taken 10, 15, and 20 days post-ovulation.
- The results showed significant overall effects of the day post-ovulation on the abundance of ER alpha and PR mRNAs in the endometrium.
- The amounts of ER alpha mRNA decreased at day 10 of pregnancy, while PR mRNA was reduced at day 5 in non-mated mares and day 15 in pregnant mares.
Experiment 2
- This study sought to determine the impact of externally administered steroids on the endometrium’s ER alpha and PR mRNA levels.
- Biopsies were obtained from 19 mares not in heat who had been treated with a control, oestradiol (estrogen), progesterone, or estrogen followed by progesterone for varying lengths of time.
- The treatment using steroids impacted the levels of ER alpha mRNA, with a higher amount seen in the group treated only with estrogen compared to those treated with a long-term combination of estrogen and progesterone.
- Importantly, this aspect of the study demonstrated that the period of dominance by progesterone can influence ER alpha gene expression.
Conclusion
- The study clearly shows changes in the amounts of steroid receptor mRNA paralleling fluctuations in the hormone environment within the uterine endometrium throughout the cycle and in early pregnancy.
- Moreover, it is suggested that factors beyond the investigated steroids could also influence ER alpha and PR gene expression in the equine uterine endometrium.
Cite This Article
APA
McDowell KJ, Adams MH, Adam CY, Simpson KS.
(2000).
Changes in equine endometrial oestrogen receptor alpha and progesterone receptor mRNAs during the oestrous cycle, early pregnancy and after treatment with exogenous steroids.
J Reprod Fertil, 117(1), 135-142.
https://doi.org/10.1530/jrf.0.1170135 Publication
Researcher Affiliations
- Department of Veterinary Science, Maxwell H Gluck Equine Research Center, University of Kentucky, Lexington 40546-0099, USA.
MeSH Terms
- Analysis of Variance
- Animals
- Autoradiography
- Cloning, Molecular
- Electrophoresis, Polyacrylamide Gel
- Endometrium / metabolism
- Estradiol / pharmacology
- Estrus / metabolism
- Female
- Gestational Age
- Horses / metabolism
- Pregnancy
- Pregnancy, Animal / metabolism
- Progesterone / pharmacology
- RNA, Messenger / analysis
- RNA, Messenger / metabolism
- Radioimmunoassay
- Receptors, Estrogen / genetics
- Receptors, Progesterone / genetics
Citations
This article has been cited 6 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).
- Jasiński T, Zdrojkowski Ł, Ferreira-Dias G, Kautz E, Juszczuk-Kubiak E, Domino M. Molecular Mechanism of Equine Endometrosis: The NF-κB-Dependent Pathway Underlies the Ovarian Steroid Receptors' Dysfunction.. Int J Mol Sci 2022 Jul 1;23(13).
- Diel de Amorim M, Klein C, Foster R, Dong L, Lopez-Rodriguez MF, Card C. Expression of Oxytocin/Neurophysin I and Oxytocinase in the Equine Conceptus from Day 8 to Day 21 Post-Ovulation.. Animals (Basel) 2022 Mar 22;12(7).
- 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.
- 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).
- Scholtz EL, Krishnan S, Ball BA, Corbin CJ, Moeller BC, Stanley SD, McDowell KJ, Hughes AL, McDonnell DP, Conley AJ. Pregnancy without progesterone in horses defines a second endogenous biopotent progesterone receptor agonist, 5α-dihydroprogesterone.. Proc Natl Acad Sci U S A 2014 Mar 4;111(9):3365-70.
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