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Estrogen metabolism by the equine embryo proper during the fourth week of pregnancy.
Abstract: Estrogen production by the trophoblast is considered important in early equine pregnancy and leads to high concentrations in yolk-sac (Y-S) fluid. The embryo proper is a potential site for their action. We examined estrogen metabolism in the embryo proper because some actions of estrogens are derived from locally formed metabolites. The embryo proper, as well as separated extraembryonic tissues, of conceptuses collected about day 25 of pregnancy, were incubated with (3)[H]-estrone (E(1)) and (3)[H]-estradiol (E(2)). Steroids were recovered from media by solid-phase extraction and eluted separately as unconjugated and conjugated fractions. Profiles of free and sulfo-conjugated fractions were obtained by HPLC. Some differences and similarities were noted for the embryo proper as compared to the extraembryonic tissues. No reduction of E(1) to E(2) was noted for the embryo proper and allantois, but some was seen with the bilaminar Y-S wall. Less conversion of E(2) to E(1) occurred in the embryo proper than in the extraembryonic tissues. Profiles for hydrolyzed sulfates from incubation of the embryo proper were very similar for both substrates, mainly with E(1) present. Thus, low levels of reductase and high levels of oxido- activities were apparent for the 17beta-hydroxysteroid dehydrogenase enzymes. Further evidence of an active role for the embryo proper was seen as minor, polar products, and an unknown compound eluting between E(2) and E(1). These findings show, for the first time, that the embryo proper can metabolize estrogens that are found in Y-S fluid - a function of potential significance at this stage in its development.
Publication Date: 2009-08-26 PubMed ID: 19710203DOI: 10.1530/REP-09-0235Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research paper is about the metabolism of estrogen, a primary female sex hormone, by embryo proper (the main mass of an embryo) in horses during the fourth week of pregnancy. The study unveils that the embryo proper is capable of metabolizing estrogens, an activity that could have significant importance during its developmental stage.
Objective of the Study
- This study aimed to examine the estrogen metabolism in embryo proper. The exploration was sparked by the understanding that some effects of estrogens are attributed to metabolites produced locally.
Methodology
- The researchers focused on the embryo proper and separated extraembryonic tissues of conceptus (embryo and its adnexa) gathered around the 25th day of pregnancy.
- These were then incubated with radioactive estrone (E(1)) and estradiol (E(2))
- Steroids were extracted separately from the media as unconjugated and conjugated fractions, followed by Profiles of free and sulfo-conjugated fractions being generated through High-Performance Liquid Chromatography (HPLC).
Findings
- The data revealed some differences and similarities between the embryo proper and the extraembryonic tissues.
- No reduction of E(1) to E(2) took place in the embryo proper and allantois. However, some reduction was observed in the bilaminar yolk-sac wall.
- Least conversion of E(2) to E(1) took place in the embryo proper compared to the extraembryonic tissues.
- Profiles procured from sulfates distilled from the embryo’s proper incubation were somewhat similar for both substrates, primarily with the presence of E(1).
Conclusions
- The results display that the embryo proper exhibits low levels of reductase and high levels of oxido-activities halting the conversion of E(2) to E(1).
- Further evidence of an active role of the embryo proper was found seen as minor, polar products, and an unknown compound, making the study the first to show that the embryo proper can metabolize estrogens circulating in the yolk-sac fluid. The function could potentially hold significance at this developmental stage.
Cite This Article
APA
Raeside JI, Christie HL, Waelchli RO, Betteridge KJ.
(2009).
Estrogen metabolism by the equine embryo proper during the fourth week of pregnancy.
Reproduction, 138(6), 953-960.
https://doi.org/10.1530/REP-09-0235 Publication
Researcher Affiliations
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada N1G2W1. jraeside@uoguelph.ca
MeSH Terms
- Amniotic Fluid / chemistry
- Amniotic Fluid / metabolism
- Animals
- Chromatography, High Pressure Liquid
- Embryo, Mammalian / chemistry
- Embryo, Mammalian / metabolism
- Estradiol / analysis
- Estradiol / metabolism
- Estradiol / pharmacokinetics
- Estrogens / analysis
- Estrogens / metabolism
- Estrone / analysis
- Estrone / metabolism
- Estrone / pharmacokinetics
- Extraembryonic Membranes / metabolism
- Female
- Gestational Age
- Horses / embryology
- Horses / metabolism
- Horses / physiology
- Pregnancy
- Pregnancy, Animal
- Steroids / analysis
- Steroids / metabolism
- Tritium / analysis
- Tritium / pharmacokinetics
Citations
This article has been cited 2 times.- 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).
- Ratto MH, Urra F, Silva M. Laterality of Ovulation and Presence of the Embryo Do Not Affect Uterine Horn Blood Flow During the First Month of Gestation in Llamas. Front Vet Sci 2020;7:598117.
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