Thyreotropic effect of human Chorionic Gonadotropin (hCG) in mares at estrus.
Abstract: The beta-subunits of thyroid stimulating hormone (TSH) and human chorionic gonadotropin (hCG) share a high homology, just like the ectodomains of their receptors, do. As a consequence, hCG was shown to exert a thyrotropic action in humans and hamsters. This study aimed to investigate whether hCG, used to induce ovulation, displays a thyrotropic effect in the equine species too. Forty mares at estrus were divided in two groups; 20 were intravenously treated with sterile saline solution (NaCl 0.9%) (group A); 20 were intravenously treated with 4000 I.U. of hCG (group B). All the mares were artificially inseminated 24 hours after the administration of the drugs and underwent blood collection at estrus detection (T1), 2, 6, 24 hours later (T2, T3, T4), and 3 and 6 days later (T5, T6), in order to detect serum fT3 and fT4 concentrations. fT3 concentrations gave rise to similar and constant trends in the two groups, without any statistically significant difference, whereas fT4 concentrations declined in both groups, remaining statistically higher in group B than in group A for 48 hours (p < 0.05), thus accounting for a thyrotropic effect of hCG. Pregnancy rate was 70% in group B and 40% in group A, respectively. The higher success in the outcome of pregnancy may result from the immunomodulating and steroidogenic effects of hCG and from the higher levels of thyroid hormones observed in the hCG treated group.
Publication Date: 2009-02-25 PubMed ID: 19235540DOI: 10.1080/08923970802668500Google Scholar: Lookup
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- Journal Article
Summary
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The research discusses the impact of human Chorionic Gonadotropin (hCG) on mares at estrus, suggesting that hCG treatment can induce a thyrotropic effect in these animals, potentially affecting pregnancy rates.
Objectives and Methodology
- The study aimed to uncover if hCG, which has been found to exert a thyrotropic action in humans and hamsters, could perform a similar function in equines (horses, specifically mares). The thyrotropic effect refers to the stimulation of the thyroid, influencing the release of thyroid hormones.
- In order to carry out this investigation, 40 mares at estrus (the fertile period in the reproductive cycle) were split into two groups. One group was treated with a sterile saline solution (Group A) and the other group was treated with 4000 I.U. of hCG (Group B).
- Both groups were artificially inseminated 24 hours after treatment. The researchers collected blood samples at fixed intervals to measure the concentration of serum fT3 and fT4 – two essential thyroid hormones.
Findings
- The study revealed that hCG does produce a thyrotropic effect in mares. While the fT3 concentrations showed similar patterns in both groups, the fT4 concentrations experienced a decline, but were statistically higher in the hCG-treated group for up to 48 hours post-treatment. This indirectly signifies hCG’s ability to stimulate the thyroid gland and influence hormone release.
- Another significant observation was the difference in pregnancy rates between the two groups. The pregnancy rate in the hCG treated group was much higher (70%) compared to the group treated with the saline solution (40%).
- The researchers speculate that this increased pregnancy rate might be due to both the immunomodulating and steroidogenic properties of hCG, as well as the enhanced levels of thyroid hormones in the hCG treated group.
Conclusion
- The study concludes that hCG has a thyrotropic impact on mares during their estrus, which might positively influence their pregnancy rates. This discovery might have significant implications for equine breeding and reproductive health.
Cite This Article
APA
Rizzo A, Mutinati M, Spedicato M, Minoia G, Trisolini C, Punzi S, Roscino MT, Jirillo F, Sciorsci R.
(2009).
Thyreotropic effect of human Chorionic Gonadotropin (hCG) in mares at estrus.
Immunopharmacol Immunotoxicol, 31(2), 299-303.
https://doi.org/10.1080/08923970802668500 Publication
Researcher Affiliations
- Department of Animal Production, Faculty of Veterinary Medicine, University of Bari, Valenzano, Bari, Italy.
MeSH Terms
- Animals
- Chorionic Gonadotropin / administration & dosage
- Estrus / blood
- Estrus / drug effects
- Estrus / metabolism
- Female
- Horses
- Insemination, Artificial
- Pregnancy
- Pregnancy, Animal / blood
- Pregnancy, Animal / drug effects
- Pregnancy, Animal / immunology
- Thyrotropin / administration & dosage
- Thyroxine / blood
- Triiodothyronine / blood
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