The effect of estradiol and progesterone on the sexual behavior of ovariectomized mares.
Abstract: Daily treatment (5 days) with estradiol resulted in increased levels (p less than 0.05) of proceptive behavior in ovariectomized as compared to control mares (N = 8 per treatment) within 4 hr of injection and for the 4 subsequent days. Ejaculations occurred more often (p less than 0.05) in estrogen-treated mares on days 2-5, but the number of precopulatory investigations by the stallions was not altered. Progesterone treatment resulted in an absence of sexual behavior except in one mare on Day 1. Control mares exhibited varying levels of sexual interest. The concurrent administration of estradiol and progesterone produced a biphasic effect on proximity-related behaviors. Proximity behaviors were initially (Day 1) greater and subsequently less in the group treated with both hormones than in the group treated with estradiol alone. Injections of free estradiol resulted in a shorter latency to effect for two measures of proceptivity than did injections of estradiol benzoate. A dose response test for progesterone showed no effect with 0, 1, or 10 mg, but 100 mg was inhibitory (p less than 0.05). These results demonstrated that within 4 hr estradiol stimulated, while progesterone inhibited estrous behavior in ovariectomized mares and that concurrent administration of estradiol and progesterone produced a biphasic effect, first enhancing, then suppressing some aspects of the estrous response. The relatively short latency to action of all treatments and the biphasic effect of concurrent estradiol and progesterone may be attributable to low level, endogenous hormones.
Publication Date: 1984-11-01 PubMed ID: 6543013DOI: 10.1016/0031-9384(84)90031-3Google Scholar: Lookup
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- Comparative Study
- 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 study found that in ovariectomized mares (female horses that have had their ovaries removed), treatment with estradiol boosted sexual behavior while treatment with progesterone inhibited it. The combined administration of both hormones initially increased proximity-related behaviors, but subsequently suppressed them.
Summary and Key Findings
- The researchers demonstrated that daily doses of estradiol could increase levels of proceptive behavior in ovariectomized mares as compared to control groups, particularly within 4 hours of injection and for the following 4 days.
- Ejaculations in mares occurred more frequently upon estrogen treatment on days 2-5. However, this did not alter the stallions’ precopulatory investigation frequency. In contrast, the treatment with progesterone nearly eliminated all sexual behavior.
- The control group exhibited varying levels of sexual interest, suggesting diverse responses to hormonal changes or treatments.
Effects of Combined Estradiol and Progesterone Administration
- The simultaneous administration of estradiol and progesterone caused a biphasic effect on proximity-related behaviors. There was an initial increase on Day 1, followed by a decrease in such behaviors.
- Both hormones influencing the sexual behavior in different phases indicate a complex interplay in hormonal regulation of sexual behavior in mares.
Estradiol Types and Dose Response of Progesterone
- The study also revealed that injections of free estradiol have a shorter reaction time for two measures of proceptivity than estradiol benzoate injections, indicating that the type of estradiol used may influence the behavior and physiological responses.
- A dose-response test for progesterone revealed that there was no effect at 0, 1, or 10 mg, but with a dose of 100 mg, it became inhibitory. Therefore, the level of progesterone dosage significantly impacts the behavior of the mares.
Conclusion
- Overall, the results showed that estradiol stimulates while progesterone inhibits estrous behavior in ovariectomized mares within a relatively short timeframe of 4 hours.
- Moreover, when estradiol and progesterone are administered concurrently, there’s a biphasic effect—first enhancing and then suppressing some aspects of estrous response. This biphasic response could be due to low-level endogenous hormones.
Cite This Article
APA
Asa CS, Goldfoot DA, Garcia MC, Ginther OJ.
(1984).
The effect of estradiol and progesterone on the sexual behavior of ovariectomized mares.
Physiol Behav, 33(5), 681-686.
https://doi.org/10.1016/0031-9384(84)90031-3 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Castration
- Drug Interactions
- Estradiol / pharmacology
- Estrus / drug effects
- Female
- Horses
- Pregnancy
- Progesterone / pharmacology
- Sexual Behavior, Animal / drug effects
Citations
This article has been cited 3 times.- Silva ESM, Newcombe JR, Cuervo-Arango J. The Effect of Treatment with Oestradiol Benzoate on Oestrus Expression and Endometrial Oedema in Anovulatory and Cyclic Mares. Animals (Basel) 2023 Mar 5;13(5).
- Broad KD, Rocha-Ferreira E, Hristova M. Placental, Matrilineal, and Epigenetic Mechanisms Promoting Environmentally Adaptive Development of the Mammalian Brain. Neural Plast 2016;2016:6827135.
- de Mestre AM, Hanlon D, Adams AP, Runcan E, Leadbeater JC, Erb HN, Costa CC, Miller D, Allen WR, Antczak DF. Functions of ectopically transplanted invasive horse trophoblast. Reproduction 2011 Jun;141(6):849-56.
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