Expression of messenger ribonucleic acid encoding for steroidogenic acute regulatory protein and enzymes, and luteinizing hormone receptor during the spring transitional season in equine follicles.
Abstract: The period of spring transition, from the anovulatory to the ovulatory season, is characterized in many mares by cyclical growth and regression of large dominant follicles. These follicles produce only low concentrations of estradiol and it is thought that acquisition of steroidogenic competence by large follicles during spring transition is prerequisite in stimulating LH prior to first ovulation. In situ hybridization was used to localize and quantify expression of factors that play a key role in follicular steroidogenesis: StAR, P450scc (CYP11A1), P450c17 (CYP17), P450arom (CYP19), and LH receptor (LHr). One ovary was obtained from mares on the day after detection of an actively growing 30 mm transitional anovulatory follicle (defined as the transitional follicle), and the remaining ovary was removed at the third estrus of the breeding season on the day after the preovulatory follicle reached 30 mm in diameter (defined as the preovulatory follicle). Messenger RNAs encoding StAR, CYP11A1, and CYP17 were detected only in theca cells and CYP19 mRNA was confined to the granulosa layer. There was significantly lower expression of mRNAs for the steroidogenic enzymes, StAR (P<0.001) and LHr (P<0.05) in transitional follicles than in preovulatory follicles. In conclusion, large equine follicles during spring transition have low levels of mRNA encoding steroidogenic enzymes, StAR and LHr which will contribute to the steroidogenic incompetence of dominant follicles during spring transition and their subsequent regression.
Publication Date: 2004-03-24 PubMed ID: 15036376DOI: 10.1016/j.domaniend.2003.10.006Google 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
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research article discusses a study that was performed to understand the spring transition period in mares, from not ovulating to ovulating. The researchers focused on several key factors involved in follicular steroidogenesis, and their expression in ovary cells during this transition.
Objective of Study
- The research study aims to understand the pattern of expression of messenger RNA encoding for several molecules during the spring transition from anovulatory to ovulatory phase in mares.
Methodology of Study
- During the study, researchers obtained ovaries from mares, and used in situ hybridization, a method that localizes specific DNA or RNA sequences in tissues or cells, to quantify the expression of StAR, CYP11A1, CYP17, CYP19, and LH receptor, which are key molecules in follicular steroidogenesis.
- The testing was conducted during two different stages. One ovary was obtained immediately after detection of a 30mm transitional anovulatory (not ovulating) follicle, defined as the transitional follicle. The remaining ovary was removed during the third estrus (a period of sexual receptivity) of the breeding season, the day after the preovulatory follicle achieved a diameter of 30mm, defined as the preovulatory follicle.
Findings of the Study
- The research findings showed that mRNA encoding for StAR, CYP11A1, and CYP17 was found only in the theca cells (cells that surround the follicle), and CYP19 mRNA was only found in the granulosa layer (cells inside the follicle).
- The data also revealed that expression for the steroidogenic enzymes, specifically StAR and LHr was significantly lower in transitional follicles than preovulatory follicles.
Conclusion of the Study
- The results of this research concluded that mares during the spring transition into ovulation have decreased levels of mRNA encoding the steroidogenic enzymes, StAR and LHr. This decrease impacts the function of dominant follicles, contributing to their eventual regression during the spring transition period.
Cite This Article
APA
Watson ED, Bae SE, Steele M, Thomassen R, Pedersen HG, Bramley T, Hogg CO, Armstrong DG.
(2004).
Expression of messenger ribonucleic acid encoding for steroidogenic acute regulatory protein and enzymes, and luteinizing hormone receptor during the spring transitional season in equine follicles.
Domest Anim Endocrinol, 26(3), 215-230.
https://doi.org/10.1016/j.domaniend.2003.10.006 Publication
Researcher Affiliations
- Department of Veterinary Clinical Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian EH25 9RG, UK. elaine.watson@ed.ac.uk
MeSH Terms
- Animals
- Aromatase / genetics
- Aromatase / metabolism
- Cholesterol Side-Chain Cleavage Enzyme / genetics
- Cholesterol Side-Chain Cleavage Enzyme / metabolism
- Cytochrome P-450 Enzyme System / biosynthesis
- Cytochrome P-450 Enzyme System / genetics
- Estradiol / metabolism
- Female
- Follicle Stimulating Hormone / blood
- Follicular Fluid / chemistry
- Horses / physiology
- In Situ Hybridization / veterinary
- Luteinizing Hormone / blood
- Ovarian Follicle / metabolism
- Ovarian Follicle / physiology
- Phosphoproteins / biosynthesis
- Phosphoproteins / genetics
- Progesterone / metabolism
- RNA, Messenger / biosynthesis
- RNA, Messenger / genetics
- Receptors, LH / biosynthesis
- Receptors, LH / genetics
- Seasons
- Steroid 17-alpha-Hydroxylase / genetics
- Steroid 17-alpha-Hydroxylase / metabolism
Citations
This article has been cited 2 times.- Coelho LA, Silva LA, Reway AP, Buonfiglio DDC, Andrade-Silva J, Gomes PRL, Cipolla-Neto J. Seasonal Variation of Melatonin Concentration and mRNA Expression of Melatonin-Related Genes in Developing Ovarian Follicles of Mares Kept under Natural Photoperiods in the Southern Hemisphere. Animals (Basel) 2023 Mar 15;13(6).
- Ishak GM, Bashir ST, Dutra GA, Gastal GDA, Gastal MO, Cavinder CA, Feugang JM, Gastal EL. In vivo antral follicle wall biopsy: a new research technique to study ovarian function at the cellular and molecular levels. Reprod Biol Endocrinol 2018 Jul 28;16(1):71.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
