Effect of ACTH (tetracosactide) on steroid hormone levels in the mare. Part B: effect in ovariectomized mares (including estrous behavior).
Abstract: The mare is the only non-primate species known to display estrous signs after ovariectomy and adrenal hormones have been implicated as a possible cause. Moreover, in several species, estradiol seems to have a stimulatory effect on the hypothalamic-pituitary-adrenal axis. The aim of the present study was to compare the effect of ACTH (tetracosactide) on pertinent hormones [cortisol, progesterone, androstenedione, testosterone (intact and ovariectomized mares) and estradiol (ovariectomized mares only)] in intact mares in estrus with the same mares after ovariectomy (n=5). Blood samples were collected hourly from 12:00 until 14:00 h the following day (half-hourly between 14:00 and 17:00 h) on two occasions, with saline or ACTH treatment at 14:00 h (saline treatment day or ACTH treatment day). The mares, both when intact and after ovariectomy, showed a significant increase in all measured hormones, except estradiol (not measured in intact mares), after ACTH treatment, lasting at least 3h post-treatment (P<0.001). On the saline treatment day, cortisol levels in ovariectomized mares were lower than in intact mares in the evening (18:00-23:00 h), but higher at night (24:00-05:00 h). No differences in cortisol response between mares, when intact and after ovariectomy, were found after ACTH treatment (P=0.3). Androstenedione levels were lower (P<0.001) and increased less after ACTH treatment in ovariectomized mares, as compared to when intact (P<0.05). Progesterone concentrations were lower in the ovariectomized mares at night (24:00-05:00 h) on the saline treatment day and at all times on the ACTH treatment day (P<0.05). Testosterone concentrations were lower in ovariectomized mares on both treatment days, as compared to when intact (P<0.001). It was concluded that ovariectomy affected basal cortisol pattern. Ovarian androstenedione and testosterone contributed to the basal circulating levels and, in the case of androstenedione, was stimulated by ACTH. Endogenous estradiol did not act stimulatory on adrenal gland hormone production in the mare.
Publication Date: 2006-07-24 PubMed ID: 16860499DOI: 10.1016/j.anireprosci.2006.06.007Google Scholar: Lookup
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- Clinical Trial
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research focuses on studying the effects of ACTH (a hormone) on levels of different hormones in ovariectomized and intact mare horses. The purpose is to understand the interplay between hormones and how the removal of ovaries can impact the hormones and behavior in mares.
Objective of the Research
The research primarily aims to determine the effect of an adrenal hormone – ACTH (tetracosactide) on diverse hormones like cortisol, progesterone, androstenedione, testosterone and estradiol. It compares the results in normal mares (intact mares) during their estrus phase with those of ovary-removed mares (ovariectomized mares).
Methodology
- The sample size for this research was five mares. Blood samples were taken from them hourly from 12:00 until 14:00 the following day and half-hourly between 14:00 and 17:00 on two different events involving either saline or ACTH treatment at 14:00.
- These tests were performed on mares as normal (intact) and after ovary removal (ovariectomized).
Findings and Results
- Results indicated an increase in all hormone levels post ACTH treatment, with the increase lasting for at least 3 hours. The ovariectomy did not influence this increase.
- During evening hours (18:00-23:00), the cortisol levels in ovary-removed mares were lesser compared to the normal ones. However, the cortisol levels were higher at night (24:00-05:00).
- After ACTH treatment, there were no significant differences in the cortisol response in normal and ovary-removed mares.
- Androstenedione levels in ovary-removed mares were lower and had a lesser increase post ACTH treatment compared to normal mares.
- Progesterone levels in ovary-removed mares were lower at night on the saline treatment day and at all times on the ACTH treatment day. Similarly, testosterone levels were lower in ovary-removed mares on both treatments day.
Conclusion
The research concludes that ovary-removal impacts the normal cortisol pattern. Also, the ovarian hormones androstenedione and testosterone contribute to the basic circulating levels. In the case of androstenedione, this contribution was stimulated by ACTH. Endogenous estradiol did not play a role in stimulating adrenal gland hormone production in the mare.
Cite This Article
APA
Hedberg Y, Dalin AM, Forsberg M, Lundeheim N, Sandh G, Hoffmann B, Ludwig C, Kindahl H.
(2006).
Effect of ACTH (tetracosactide) on steroid hormone levels in the mare. Part B: effect in ovariectomized mares (including estrous behavior).
Anim Reprod Sci, 100(1-2), 92-106.
https://doi.org/10.1016/j.anireprosci.2006.06.007 Publication
Researcher Affiliations
- Division of Comparative Reproduction, Obstetrics and Udder Health, Department of Clinical Sciences, P.O. Box 7054, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden. ylva.hedberg@kv.slu.se
MeSH Terms
- Androstenedione / blood
- Animals
- Behavior, Animal / drug effects
- Behavior, Animal / physiology
- Cosyntropin / pharmacology
- Estradiol / blood
- Estrous Cycle / drug effects
- Female
- Horses / blood
- Horses / physiology
- Hydrocortisone / blood
- Ovariectomy / veterinary
- Progesterone / blood
- Testosterone / blood
- Time Factors
Citations
This article has been cited 8 times.- Aurich C, Kaps M. Suppression of reproductive behaviour and gonadal function in female horses-An update. Reprod Domest Anim 2022 Sep;57 Suppl 4(Suppl 4):4-12.
- Hicks GR, Fraser NS, Bertin FR. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals (Basel) 2021 Mar 20;11(3).
- Satué K, Fazio E, Muñoz A, Medica P. Endocrine and Electrolyte Balances during Periovulatory Period in Cycling Mares. Animals (Basel) 2021 Feb 17;11(2).
- Devick IF, Leise BS, McCue PM, Rao S, Hendrickson DA. Ovarian histopathology, pre- and post-operative endocrinological analysis and behavior alterations in 27 mares undergoing bilateral standing laparoscopic ovariectomy. Can Vet J 2020 Feb;61(2):181-186.
- Morgan RA, Keen JA, Homer N, Nixon M, McKinnon-Garvin AM, Moses-Williams JA, Davis SR, Hadoke PWF, Walker BR. Dysregulation of Cortisol Metabolism in Equine Pituitary Pars Intermedia Dysfunction. Endocrinology 2018 Nov 1;159(11):3791-3800.
- Alm YH, Sukjumlong S, Kindahl H, Dalin AM. Steroid hormone receptors ERalpha and PR characterised by immunohistochemistry in the mare adrenal gland. Acta Vet Scand 2009 Jul 22;51(1):31.
- Samie KA, Kowalewski MP, Schuler G, Gastal GDA, Bollwein H, Scarlet D. Roles of GDF9 and BMP15 in equine follicular development: in vivo content and in vitro effects of IGF1 and cortisol on granulosa cells. BMC Vet Res 2025 Apr 27;21(1):292.
- Wattanathorn J, Thukham-Mee W. Omega-3-Rich Tuna Oil Derived from By-Products of the Canned Tuna Industry Enhances Memory in an Ovariectomized Rat Model of Menopause. Antioxidants (Basel) 2024 May 24;13(6).
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