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Expression and binding activity of luteinizing hormone/chorionic gonadotropin receptors in the primary corpus luteum during early pregnancy in the mare.
Abstract: Luteal steroids are necessary to maintain the first 70-90 days of pregnancy in the mare. At 35 days postovulation, the resurgence of the primary corpus luteum (CL) coincides with the secretion of the fetal hormone eCG. In order to study the responsiveness of the primary CL to eCG, we have examined levels of luteal equine LH/CG receptors (eLH/CG-R) mRNAs by Northern blot analysis and measured concentrations of eLH/CG binding sites on luteal membranes using 125I-eLH saturation binding assays at three stages of gestation: before the onset of eCG secretion (Days 14-31), from onset to maximum eCG secretion (Days 38-62), and during decline of eCG secretion (Days 83-101). Multiple transcripts of eLH/CG-R (7, 5.7, 4.9, 3.9, 2.8, 1.8, 0.6 kilobase [kb]) were identified in the primary CL at all stages examined. Three of them (5.7, 2.8, 0.6 kb) coded for truncated eLH/CG-R lacking the transmembrane domain. The relative intensities of the four major transcripts tended to decrease (5.7 and 3.9 kb) or were steadily expressed (7 and 1.8 kb) during pregnancy. The affinity of eLH/CG binding sites did not change during pregnancy whereas the number of eLH/CG binding sites decreased significantly after the onset of eCG secretion. Nevertheless, levels of binding sites were still at 44.6% (Days 38-62) to 24.7% (Days 83-101) of those measured before the onset of eCG secretion. Taken together, the presence of eLH/CG-R mRNAs and of a substantial part of eLH/CG binding sites with high affinity suggest that the primary CL still expresses a high number of eLH/CG-R and remains responsive to eCG during early pregnancy.
Publication Date: 2003-07-30 PubMed ID: 12890729DOI: 10.1095/biolreprod.103.018812Google 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 explores how luteinizing hormone/chorionic gonadotropin receptors (LH/CG-R) in the primary corpus luteum in mares respond to the fetal hormone eCG during early pregnancy. The study examined LH/CG-R levels and binding activity at different stages of gestation, revealing that the primary corpus luteum continues to express a significant amount of these receptors and remains responsive to eCG.
About the Study
- The researchers were interested in how the primary corpus luteum (CL) in mares responds to the fetal hormone eCG during early pregnancy.
- They examined the levels of luteal equine LH/CG receptors (eLH/CG-R) mRNAs and measured the concentrations of eLH/CG binding sites on luteal membranes at three stages of gestation.
Research Methods
- The researchers conducted a Northern blot analysis to examine the levels of eLH/CG-R mRNAs.
- They used 125I-eLH saturation binding assays to measure the concentrations of eLH/CG binding sites on luteal membranes.
- The measurements were made before the onset of eCG secretion, from the onset to the maximum eCG secretion, and during the decline of eCG secretion.
Findings
- The analysis identified multiple transcripts of eLH/CG-R in the primary CL at all stages of gestation.
- Three of these transcripts coded for truncated eLH/CG-R, lacking the transmembrane domain.
- The relative intensities of the four major transcripts either decreased or were steadily expressed during pregnancy.
- The affinity of eLH/CG binding sites did not change during pregnancy; however, the number of such sites decreased considerably after the onset of eCG secretion.
- Despite the decrease, the levels of binding sites were still significant at 44.6% to 24.7% of those measured before the onset of eCG secretion.
Conclusion
- The presence of eLH/CG-R mRNAs and a substantial number of eLH/CG binding sites with high affinity suggest that the primary corpus luteum continues to express a high amount of eLH/CG-R and remains responsive to eCG during early pregnancy.
Cite This Article
APA
Saint-Dizier M, Chopineau M, Dupont J, Daels PF, Combarnous Y.
(2003).
Expression and binding activity of luteinizing hormone/chorionic gonadotropin receptors in the primary corpus luteum during early pregnancy in the mare.
Biol Reprod, 69(5), 1743-1749.
https://doi.org/10.1095/biolreprod.103.018812 Publication
Researcher Affiliations
- Unité de Physiologie de la Reproduction et des Comportements, UMR 6073 INRA-CNRS-Université F. Rabelais de Tours, 37380 Nouzilly, France. dizier@tours.inra.fr
MeSH Terms
- Animals
- Binding Sites
- Blotting, Northern
- Cell Membrane / metabolism
- Corpus Luteum / metabolism
- DNA, Complementary / biosynthesis
- DNA, Complementary / genetics
- Female
- Gene Expression Regulation, Developmental / genetics
- Gene Expression Regulation, Developmental / physiology
- Horses / physiology
- Luteal Cells / metabolism
- Pregnancy
- Pregnancy, Animal / metabolism
- RNA, Messenger / biosynthesis
- Radioligand Assay
- Receptors, LH / biosynthesis
- Receptors, LH / metabolism
- Reverse Transcriptase Polymerase Chain Reaction
Citations
This article has been cited 3 times.- Read JE, Cabrera-Sharp V, Kitscha P, Cartwright JE, King PJ, Fowkes RC, de Mestre AM. Glial Cells Missing 1 Regulates Equine Chorionic Gonadotrophin Beta Subunit via Binding to the Proximal Promoter. Front Endocrinol (Lausanne) 2018;9:195.
- Menon KM, Menon B. Structure, function and regulation of gonadotropin receptors - a perspective. Mol Cell Endocrinol 2012 Jun 5;356(1-2):88-97.
- Han B, Wang ZQ, Xue LQ, Ma JH, Liu W, Liu BL, Wu JJ, Pan CM, Chen X, Zhao SX, Lu YL, Wu WL, Qiao J, Song HD. Functional study of an aberrant splicing variant of the human luteinizing hormone (LH) receptor. Mol Hum Reprod 2012 Mar;18(3):129-35.
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