Effects of melatonin implants in pony mares. 1. Acute effects.
Abstract: The effects of melatonin implant treatment over a four week period on LH, estradiol (E2) and progesterone (P4) secretion during the breeding season were studied in ovary-intact and ovariectomized pony mares. Mares with melatonin implants had significantly higher daytime melatonin concentrations than mares with sharm implants (P = 0.0065). In ovariectomized mares, LH secretion did not differ between mares with melatonin and sham implants. In ovary-intact mares, melatonin implants altered the pattern of LH secretion (P = 0.0023) in such a way that an increase in LH secretion was observed during the periovulatory period. Estradiol and P4 secretion were unaffected by melatonin implants. These results suggest that constant administration of melatonin may enhance the secretion of LH during the periovulatory surge but does not adversely affect E2, P4 or basal LH secretion in mares during the breeding season.
Publication Date: 2000-03-25 PubMed ID: 10732050DOI: 10.1016/s0093-691x(98)00060-0Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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The research investigates the impact of melatonin implants over four weeks on the hormones LH, estradiol (E2), and progesterone (P4) during the pony mares’ breeding season. It was observed that mares with melatonin implants had higher daytime melatonin levels and saw an increase in LH secretion during the periovulatory surge, without any negative effect on E2, P4, or basal LH secretion.
Research Method
- The research was conducted on pony mares both with ovaries intact and those who were ovariectomized to study the individual effects of melatonin implant treatment during the breeding season.
- The main focus was on examining how these implants affect three key hormones: Luteinizing Hormone (LH), estradiol (E2), and progesterone (P4).
Results and Findings
- After the treatment period, it was found that mares implanted with melatonin had significantly higher melatonin concentrations during the day compared to those with sham implants.
- Interestingly, the treatment did not cause any significant changes in LH secretion in ovariectomized mares. Hence, the presence of ovaries might play a crucial role in the hormonal responses affected by melatonin.
- In contrast, for mares with their ovaries intact, melatonin implants significantly affected the pattern of LH secretion, leading to increased LH secretion during the periovulatory period.
- Despite these hormonal shifts, the secretion of estradiol (E2) and progesterone (P4), two key hormones in the reproductive cycle, were not affected by the melatonin implants.
Conclusion Drawn
- The study concludes that constant administration of melatonin could enhance LH secretion during the periovulatory surge.
- Moreover, the use of melatonin does not adversely affect basal LH secretion, estradiol, or progesterone in the mares during their breeding season. Thus, melatonin implants might be used as a method to control or stimulate LH secretion during the reproductive cycle without affecting the other hormones significantly.
Cite This Article
APA
Peltier MR, Robinson G, Sharp DC.
(2000).
Effects of melatonin implants in pony mares. 1. Acute effects.
Theriogenology, 49(6), 1113-1123.
https://doi.org/10.1016/s0093-691x(98)00060-0 Publication
Researcher Affiliations
- Department of Animal Science, University of Florida, Gainesville 32611-0701, USA.
MeSH Terms
- Animals
- Drug Implants
- Estradiol / blood
- Estradiol / metabolism
- Female
- Horses / physiology
- Least-Squares Analysis
- Linear Models
- Luteinizing Hormone / blood
- Luteinizing Hormone / metabolism
- Melatonin / administration & dosage
- Melatonin / blood
- Menstrual Cycle / drug effects
- Menstrual Cycle / physiology
- Ovariectomy / veterinary
- Ovary / drug effects
- Ovary / metabolism
- Ovary / physiology
- Photoperiod
- Progesterone / blood
- Progesterone / metabolism
- Radioimmunoassay / veterinary
- Regression Analysis
- Scintillation Counting / veterinary
Citations
This article has been cited 1 times.- El Allali K, Sghiri A, Bouâouda H, Achaâban MR, Ouzir M, Bothorel B, El Mzibri M, El Abbadi N, Moutaouakkil A, Tibary A, Pévet P. Effect of Melatonin Implants during the Non-Breeding Season on the Onset of Ovarian Activity and the Plasma Prolactin in Dromedary Camel. Front Vet Sci 2018;5:44.
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