Effect of daily clenbuterol and exogenous melatonin treatment on body fat, serum leptin and the expression of seasonal anestrus in the mare.
Abstract: A small percentage of mature mares continue to exhibit estrous cyclicity during the non-breeding season which is of interest because of the importance of timing of the breeding season to the equine breeding industry. Previously, it was demonstrated that the continuation of estrous cycles was more likely to occur in mature than young mares. Additionally, an apparent association exists between elevated body fat and increased circulating concentrations of leptin, and the occurrence of estrous cycles during the non-breeding season. Two experiments were conducted to test the hypothesis that pharmacological manipulation of body fat and leptin by administration of the beta(2)-adrenergic receptor agonist clenbuterol, with and without continuous treatment with melatonin, would increase the proportion of mares entering anestrus or advance its timing. In Experiment 1, eight mature mares were administered clenbuterol (3.2 microg/kg) daily from October through January and six mares were untreated. In Experiment 2, eight mares were administered clenbuterol daily from June through December, eight mares were treated with continuous release melatonin implants, and seven mares were treated with both clenbuterol and melatonin. Melatonin treatment was included to confirm previous results that constant treatment with melatonin did not advance the timing of anestrus. In both studies, leptin concentrations (P<0.01, both experiments) and body fat percentage (P<0.01, Experiment 1; P<0.05, Experiment 2) declined in response to daily clenbuterol treatment. Unexpectedly, however, this decrease was attenuated in mares also treated with melatonin (P0.05). The results demonstrate the manipulation of body condition via pharmacological intervention does not modify the mechanisms controlling seasonal anestrus in the mare.
Publication Date: 2003-02-15 PubMed ID: 12586494DOI: 10.1016/s0378-4320(02)00246-4Google Scholar: Lookup
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- Journal Article
Summary
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This research investigated the effects of certain pharmacological treatments on the body fat, serum leptin levels, and the onset of anestrus (the period of sexual inactivity or quiescence) in mares. They found that while certain treatments led to a decline in body fat and leptin levels, it did not change the onset of the anestrus period.
Objective of Research
- The research primarily aimed to understand if pharmacological manipulation of body fat and leptin could influence the anestrus period in mares. This is significant due to the implications it could have on the timing of the equine breeding season.
- It focused on the administration of clenbuterol, a beta(2)-adrenergic receptor agonist, with and without continuous treatment with melatonin, to test its impact on body fat, leptin levels, and anestrus onset.
Research Method and Experiments
- Two experiments were conducted. In the first, eight mature mares were given a daily dose of clenbuterol from October to January, and six mares remained untreated. In the second experiment, clenbuterol was given to eight mares daily from June to December; eight mares received melatonin implants, and seven mares underwent both therapies.
- Melatonin treatment was included to confirm prior findings that constant melatonin treatment did not advance the timing of anestrus.
Key Research Findings
- Both experiments found that leptin concentrations and body fat declined in response to daily clenbuterol treatment. However, this effect was lessened in mares also treated with melatonin.
- Despite the decline in body fat and leptin levels in mares treated with clenbuterol, the timing or proportion of mares entering anestrus remained unchanged.
- These results suggest that while pharmacological intervention can alter body condition, it does not modify the mechanisms that control the seasonal anestrus period in mares.
Cite This Article
APA
McManus CJ, Fitzgerald BP.
(2003).
Effect of daily clenbuterol and exogenous melatonin treatment on body fat, serum leptin and the expression of seasonal anestrus in the mare.
Anim Reprod Sci, 76(3-4), 217-230.
https://doi.org/10.1016/s0378-4320(02)00246-4 Publication
Researcher Affiliations
- Department of Veterinary Science, Maxwell Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546-0099, USA.
MeSH Terms
- Adipose Tissue
- Adrenergic beta-Agonists / administration & dosage
- Anestrus / drug effects
- Animals
- Body Composition / drug effects
- Breeding
- Circadian Rhythm
- Clenbuterol / administration & dosage
- Drug Implants
- Female
- Horses / physiology
- Leptin / blood
- Melatonin / administration & dosage
- Progesterone / blood
- Seasons
Citations
This article has been cited 1 times.- Salazar-Ortiz J, Camous S, Briant C, Lardic L, Chesneau D, Guillaume D. Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus). Reprod Biol Endocrinol 2011 Sep 29;9:130.
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