The binding of FSH, LH and PMSG to equine gonadal tissues.
Abstract: Gonadotrophin-receptor binding studies involving the use of 125I-labelled highly purified FSH and LH have shown that equine gonadal tissues possess similar numbers of specific FSH and LH receptors per cell as the gonadal tissues of other mammals. However, while rat, cow and pig gonadal tissues were shown to bind as much 125I-labelled PMSG as 125I-labelled LH on a molar basis, the equivalent equine tissues bound only less than or equal to 4% as much of the labelled PMSG as LH. Competitive binding studies involving the use of radioreceptor assay techniques have further demonstrated that the small but significant degree of PMSG binding which does take place to equine tissues occurs at LH receptors and not at receptors specific for PMSG. The binding of PMSG to equine FSH receptors was negligible. These results suggest that PMSG (1) binds to equine LH receptors with about one-tenth the affinity of that observed with LH receptors of other species and (2) does not appear to bind specifically to equine FSH receptors. This would possibly explain the apparent refractoriness of mares' ovaries to exogenous and endogenous OMSG.
Publication Date: 1979-01-01 PubMed ID: 225496
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- Journal Article
Summary
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The research article explores how horse gonadal tissues bind with FSH, LH and PMSG – hormones that affect mammalian ovaries. These results suggest a possible reason why horse ovaries might not respond effectively to OMSG, both externally and internally introduced.
Understanding Hormone Binding in Equine Gonadal Tissues
- The research conducts gonadotrophin-receptor binding studies using 125I-labelled highly purified FSH (Follicle-stimulating hormone) and LH (Luteinizing hormone). Both of these hormones are important in the reproductive process of mammals.
- The researchers found that horse gonadal tissues (ovaries/testes) have similar numbers of specific FSH and LH receptors per cell compared to the gonadal tissues of other mammals like rats, cows, and pigs.
Comparing Hormone Binding in Different Species
- While rat, cow, and pig gonadal tissues were shown to bind as much 125I-labelled PMSG (Pregnant Mare’s Serum Gonadotrophin) as 125I-labelled LH on a molar basis, the equivalent horse tissues only bound to less than or equal to 4% of the labelled PMSG as LH.
- Competitive binding studies involving radioreceptor assay techniques further demonstrated that the small but significant amount of PMSG binding that does take place in horse tissues occurs at LH receptors, not receptors specific for PMSG.
PMSG Binding to Equine FSH Receptors
- Importantly, the research highlights that the binding of PMSG to horse FSH receptors is negligible; a significantly lower binding compared to other tested species, suggesting that PMSG binds to equine LH receptors with about one-tenth the affinity observed with the LH receptors of other species.
- The study confirms that PMSG does not appear to bind specifically to horse FSH receptors.
Relevance to Ovarian Reactivity in Mares
- These findings potentially explain the specific behavior of mares’ ovaries: their non-reactivity or “refractoriness” to exogenous (externally introduced) and endogenous (internally produced) OMSG (Pregnant Mare’s Serum Gonadotrophin).
Cite This Article
APA
Stewart F, Allen WR.
(1979).
The binding of FSH, LH and PMSG to equine gonadal tissues.
J Reprod Fertil Suppl(27), 431-440.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Binding, Competitive
- Corpus Luteum / metabolism
- Female
- Follicle Stimulating Hormone / metabolism
- Gonadotropins, Equine / metabolism
- Horses / physiology
- Luteinizing Hormone / metabolism
- Male
- Ovarian Follicle / metabolism
- Ovary / metabolism
- Pregnancy
- Receptors, Cell Surface / metabolism
- Testis / metabolism
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.
- Cohen L, Bousfield GR, Ben-Menahem D. The recombinant equine LHβ subunit combines divergent intracellular traits of human LHβ and CGβ subunits.. Theriogenology 2015 Jun;83(9):1469-76.
- de Mestre AM, Hanlon D, Adams AP, Runcan E, Leadbeater JC, Erb HN, Costa CC, Miller D, Allen WR, Antczak DF. Functions of ectopically transplanted invasive horse trophoblast.. Reproduction 2011 Jun;141(6):849-56.
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