Gonadotropin secretion in ovariectomized pony mares treated with dexamethasone or progesterone and subsequently with dihydrotestosterone.
Abstract: Twelve long-term ovariectomized (OVX) pony mares were used to determine the effects of dexamethasone (DEX) or progesterone (PR) on concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in daily blood samples and after administration of gonadotropin releasing hormone (GnRH). All mares were subsequently administered dihydrotestosterone (DHT) to determine if DEX or PR treatment altered the FSH or LH response to this androgen. Daily blood sampling was started on day 1. After a pretreatment injection of GnRH on day 5, four mares were administered DEX at 125 micrograms/kg of body weight (BW), four mares were administered PR at 500 micrograms/kg of BW and four mares were administered vehicle. Injections were given subcutaneously in vegetable shortening daily through day 14. After a second injection of GnRH on day 15, all mares were administered DHT in shortening at 150 micrograms/kg of BW. Injections of DHT were given daily through day 24. A final injection of GnRH was given on day 25. Treatment of mares with DEX 1) reduced (P less than .01) daily LH secretion and briefly increased (P less than .05) daily FSH secretion and 2) increased (P less than .01) the FSH response to exogenous GnRH. Treatment of mares with PR had no effect on daily LH secretion but increased (P less than .05) daily FSH secretion and increased (P less than .01) the FSH response to exogenous GnRH.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1988-04-01 PubMed ID: 3147167DOI: 10.1016/0739-7240(88)90015-xGoogle Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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This research study investigates the effects of dexamethasone and progesterone on hormone concentrations and response in ovariectomized pony mares, followed by an examination of any changes in response after the administration of dihydrotestosterone.
Study Design and Method
- The researchers carried out their study on twelve long-term ovariectomized (OVX) pony mares.
- The study looked at the influence of dexamethasone (DEX) and progesterone (PR) on the concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH). These levels were measured in daily blood samples and after administering a gonadotropin-releasing hormone (GnRH).
- Following the administration of DEX and PR, all mares were given dihydrotestosterone (DHT) with the aim of observing if the initial treatment with DEX or PR would alter the FSH or LH reaction to this male hormone.
Treatment and Sampling
- Treatment started on day 1 with daily blood sampling.
- On the fifth day, a pretreatment injection of GnRH was administered, followed by DEX or PR injections (four mares each) at varying daily dosages. The remaining four mares were given a control treatment (vehicle).
- These daily injections were given subcutaneously in vegetable shortening right through day 14, followed by another injection of GnRH on day 15.
- Subsequently, all mares were administered DHT mixed in shortening at a particular dosage daily through day 24. A final injection of GnRH was given on day 25.
Research Findings
- Treatment with dexamethasone resulted in a decreased LH secretion and a brief increase in daily FSH secretion. It also heightened the FSH response to the injected GnRH.
- Progesterone treatment did not affect daily LH secretion. However, it increased the daily FSH secretion and significantly increased the FSH response to the injected GnRH.
In conclusion, this study provides valuable insights into the hormonal interactions and reactions to certain medications in ovariectomized pony mares. It showcases the varying impacts of dexamethasone and progesterone on hormone concentrations.
Cite This Article
APA
McNeill-Wiest DR, Thompson DL, Wiest JJ.
(1988).
Gonadotropin secretion in ovariectomized pony mares treated with dexamethasone or progesterone and subsequently with dihydrotestosterone.
Domest Anim Endocrinol, 5(2), 149-155.
https://doi.org/10.1016/0739-7240(88)90015-x Publication
Researcher Affiliations
- Department of Animal Science, Louisiana State University Agricultural Center, Baton Rouge 70803.
MeSH Terms
- Animals
- Dexamethasone / pharmacology
- Dihydrotestosterone / pharmacology
- Female
- Follicle Stimulating Hormone / blood
- Follicle Stimulating Hormone / metabolism
- Horses / physiology
- Luteinizing Hormone / blood
- Luteinizing Hormone / metabolism
- Ovariectomy / veterinary
- Pituitary Hormone-Releasing Hormones / pharmacology
- Progesterone / pharmacology
Citations
This article has been cited 1 times.- Canisso IF, Segabinazzi LGTM, Fedorka CE. Persistent Breeding-Induced Endometritis in Mares - a Multifaceted Challenge: From Clinical Aspects to Immunopathogenesis and Pathobiology. Int J Mol Sci 2020 Feb 20;21(4).
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