Production of 5 alpha-dihydroprogesterone during late pregnancy in the mare.
Abstract: Changes in the progesterone metabolite 5 alpha-dihydroprogesterone (5 alpha-DHP) in maternal plasma in late gestation, and possible sites of production of this steroid were studied in pony and Thoroughbred mares by an enzyme-linked immunosorbant assay for 5 alpha-DHP. In Thoroughbred mares, plasma 5 alpha-DHP increased from 63.7 +/- 10.5 ng/ml (27 days pre-partum) to 161.7 +/- 30.8 ng/ml (1 day pre-partum) falling to 90.2 +/- 16.1 ng/ml on the day of parturition. In pony mares, values rose from 30.8 +/- 8.1 ng/ml (27 days pre-partum) to 79.1 +/- 30.8 ng/ml (3 days pre-partum) and then decreased to 28.2 +/- 7.1 ng/ml on the day of parturition. Concentrations of 5 alpha-DHP were greater in the umbilical and uterine veins than in the corresponding umbilical and uterine artery samples. Tissues incubated with isotopically-labelled substrates showed that the fetal placenta converted pregnenolone to progesterone (47.5 +/- 9.0%). Endometrium metabolised [3H]pregnenolone to progesterone and 5 alpha-DHP (11.0 +/- 3.0% and 7.8 +/- 2.4%, respectively), and [14C]progesterone to 5 alpha-DHP (9.3 +/- 2.5%). Deuterium-labelled substrates were used to confirm the identity of these products by gas chromatography-mass spectrometry. Negligible amounts of 5 alpha-DHP were formed by other fetal tissues (adrenal, liver, kidney and testis). The results show that 5 alpha-DHP production in late pregnancy is derived primarily from endometrial metabolism of pregnenolone and/or progesterone.
Publication Date: 1991-01-01 PubMed ID: 1795296
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research studied the hormone 5 alpha-dihydroprogesterone (5 alpha-DHP), a metabolite of progesterone, during late pregnancy in mares, using enzyme-linked immunosorbant assay. It found that the hormone’s production in late pregnancy is primarily resulting from the endometrial metabolism of pregnenolone and/or progesterone.
Study Background
- The focus of the research was on the hormone 5 alpha-DHP, a metabolite of progesterone, in late pregnancy in thoroughbred and pony mares.
- The hormone’s levels in the maternal plasma were studied during late gestation, and potential sources of this hormone production were evaluated.
- The researchers utilized an enzyme-linked immunosorbant assay (a type of test used in medical diagnostics) to track 5 alpha-DHP levels.
Experiment and Results
- In Thoroughbred mares, plasma 5 alpha-DHP increased from 63.7 +/- 10.5 ng/ml (27 days before giving birth) to 161.7 +/- 30.8 ng/ml (1 day before giving birth), then decreased to 90.2 +/- 16.1 ng/ml on the day of birth.
- In pony mares, values rose from 30.8 +/- 8.1 ng/ml (27 days before birth) to 79.1 +/- 30.8 ng/ml (3 days before birth). The levels then dropped to 28.2 +/- 7.1 ng/ml on the day of birth.
- Levels of 5 alpha-DHP were higher in the umbilical and uterine veins than in the corresponding arteries.
- To understand which tissues produced 5 alpha-DHP, tissues were incubated with isotopically-labelled substrates. This revealed that the fetal placenta transformed pregnenolone (a parent compound) into progesterone (47.5 +/- 9.0%).
- The endometrium (the uterine lining) metabolised [3H]pregnenolone to progesterone and 5 alpha-DHP (11.0 +/- 3.0% and 7.8 +/- 2.4%, respectively), and [14C]progesterone to 5 alpha-DHP (9.3 +/- 2.5%).
Conclusion
- The research concluded that the production of 5 alpha-DHP in late pregnancy largely originates from endometrial metabolism of pregnenolone and/or progesterone.
- This indicates that changes in hormone levels may be a key factor in late equine pregnancy.
- However, negligible production of 5 alpha-DHP was observed in other fetal tissues like adrenal, liver, kidney and testis.
Cite This Article
APA
Hamon M, Clarke SW, Houghton E, Fowden AL, Silver M, Rossdale PD, Ousey JC, Heap RB.
(1991).
Production of 5 alpha-dihydroprogesterone during late pregnancy in the mare.
J Reprod Fertil Suppl, 44, 529-535.
Publication
Researcher Affiliations
- AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K.
MeSH Terms
- 5-alpha-Dihydroprogesterone
- Animals
- Female
- Fetal Blood / chemistry
- Gestational Age
- Horses / blood
- Pregnancy
- Pregnancy, Animal / blood
- Pregnanediones / blood
- Pregnanediones / metabolism
- Pregnenolone / metabolism
- Progesterone / metabolism
- Uterus / blood supply
Citations
This article has been cited 4 times.- 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.
- Wierer M, Schrey AK, Kühne R, Ulbrich SE, Meyer HH. A single glycine-alanine exchange directs ligand specificity of the elephant progestin receptor. PLoS One 2012;7(11):e50350.
- Allen WR. Ovulation, pregnancy, placentation and husbandry in the African elephant (Loxodonta africana). Philos Trans R Soc Lond B Biol Sci 2006 May 29;361(1469):821-34.
- Veronesi MC, Cotticelli A, Pividori I, Giombolini M, Corazzin M, Ellero L, Peric T. From Pre-Foaling to Late Pregnancy: Cortisol, DHEA(S), Progesterone, 17-β-Estradiol, and Allopregnanolone Hair Concentration Profiles in Standardbred Mares. Animals (Basel) 2025 Jan 23;15(3).
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