Expression and localization of relaxin in the ovary of the mare.
Abstract: Immunoreactive, chromatographic and molecular techniques were used to study the expression of relaxin in mare ovaries at different stages of the oestrous cycle. Relaxin in follicular fluid ranged from 1.6 to 2.5, from 1.4 to 5.2, from 1.2 to 6.7 and from 1.0 to 3.5 ng ml-1 in small ( 2 3 4 cm) follicles, respectively, and total content of fluid relaxin per follicle increased (P < 0.05) with follicular size. When subjected to reverse phase HPLC analysis, follicular fluid yielded absorbance profiles corresponding closely to those of purified relaxin, and immunoreactive peaks in follicular fluid fractions measured by radioimmunoassay matched peaks of the relaxin standard. While relaxin was localized immunocytochemically to granulosa and theca cells of preovulatory follicles, northern blot and reverse transcriptase-PCR followed by Southern blot analysis failed to detect a relaxin transcript in these tissues. A single relaxin transcript (428 bp) corresponding to mRNA encoding relaxin was identified in early, mid- and late stage corpora lutea but not in corpora haemorrhagica or albicantia. Northern blot analysis revealed a weakly expressed 1 kb transcript in total cellular RNA from mature corpora lutea. In situ hybridization studies localized the mRNA to the large luteal cells of mature corpora lutea and relaxin protein was detected by immunocytochemistry in the same tissue. This is the first report demonstrating relaxin in the equine ovary and its expression by luteal cells, thereby suggesting a role for relaxin in follicular or corpus luteum function in cyclic mares.
Publication Date: 1997-07-01 PubMed ID: 9306987DOI: 10.1530/jrf.0.1100329Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the presence and function of a protein called relaxin in the ovaries of mares during different stages of the oestrous cycle using various scientific techniques.
Research Methods and Findings
- The researchers used methods such as immunoreactivity, chromatography, and molecular techniques to study the expression and location of relaxin in the ovarian tissue of mares. These methods allow scientists to identify and observe specific proteins within a tissue sample.
- The levels of relaxin were measured in the follicular fluid within the mare’s ovaries. The fluid was gathered from follicles of varying sizes and at different stages of the oestrous cycle. It was found that the concentration of relaxin increased with the size of the follicle.
- High-performance liquid chromatography (HPLC) was used to further analyze the follicular fluid. The results showed absorbance profiles that closely matched those of purified relaxin, confirming the presence of relaxin in the fluid.
- Immunocytochemical localization showed the presence of relaxin in the granulosa and theca cells of the preovulatory follicles. However, northern blot analysis and reverse transcriptase-PCR didn’t detect a relaxin transcript in these tissues.
- A relaxin transcript was identified in the early, mid, and late stage corpora lutea but not in corpora haemorrhagica or albicantia. The large luteal cells of mature corpora lutea were also found to express mRNA for relaxin, and relaxin protein was detected in the same tissue using immunocytochemistry.
Significance and Implications
- These findings provide the first evidence of relaxin in the mare’s ovaries and its expression by luteal cells. The protein has been previously identified in pregnancy and labour for its role in the relaxation of uterine muscles and cervix, but this study suggests that it may also have a role in the oestrous cycle of mares.
- This implies that relaxin could contribute to follicular growth or the function of the corpus luteum in cyclic mares. The corpus luteum is crucial for the regulation of the oestrous cycle and pregnancy in mares, and any insight into its function could have valuable implications for reproductive healthcare and breeding management in horses.
Cite This Article
APA
Ryan PL, Klonisch T, Yamashiro S, Renaud RL, Wasnidge C, Porter DG.
(1997).
Expression and localization of relaxin in the ovary of the mare.
J Reprod Fertil, 110(2), 329-338.
https://doi.org/10.1530/jrf.0.1100329 Publication
Researcher Affiliations
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
MeSH Terms
- Animals
- Blotting, Northern
- Blotting, Southern
- Chromatography, High Pressure Liquid
- Corpus Luteum / chemistry
- Estrus / metabolism
- Female
- Follicular Fluid / chemistry
- Horses / metabolism
- Immunohistochemistry
- In Situ Hybridization
- Ovarian Follicle / physiology
- Ovary / metabolism
- Polymerase Chain Reaction
- RNA, Messenger / analysis
- Relaxin / analysis
- Relaxin / genetics
- Relaxin / metabolism
Citations
This article has been cited 2 times.- Nowak M, Boos A, Kowalewski MP. Luteal and hypophyseal expression of the canine relaxin (RLN) system during pregnancy: Implications for luteotropic function. PLoS One 2018;13(1):e0191374.
- Peserico A, Barboni B, Camerano Spelta Rapini C, Di Berardino C, Capacchietti G, Canciello A, Konstantinidou F, Donato M, Stuppia L, Gatta V. Transcriptomic Profile of Early Antral Follicles: Predictive Somatic Gene Markers of Oocyte Maturation Outcome. Cells 2025 May 12;14(10).
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