Testicular endocrine function, seasonality and semen quality of the stallion.
Abstract: To gain further information on gonadal function of the stallion, concentrations of testicular steroids in blood plasma (bpl) and seminal plasma (spl) and their distribution in the ejaculate were determined. Blood and semen samples from a total of 11 stallions were collected from November to July. Estrone (E1), estrone sulfate (E1S), estradiol-17beta (E2beta) and testosterone (T) were determined in bpl and spl, and in addition androstenedione (A), dehydroepiandrosterone (DHEA) and 5alpha-dihydrotestosterone (5alpha-DHT) were measured in spl. At certain points of time, aliquots of an ejaculate were centrifuged, washed and the distribution of E1, E1S, E2beta and T into seminal plasma and the sperm fraction was assessed. Hormone assay was by RIA, partly after prior separation by HPLC. Mean concentrations (X(g) x DF) were as follows: E2beta (bpl) 31.1 (1.16), (spl) 24.2 (1.42) pg ml(-1); E1 (bpl) 143.3 (1.21), (spl) 117.7 (1.53) pg ml(-1); E1S (bpl) 157.3 (1.44), (spl) 2.92 (1.42) ng ml(-1); T (bpl) 570.6 (1.43), (spl) 23.1 (1.68) pg ml(-1); A (spl) 17.9 (1.39) pg ml(-1); DHEH (spl) 12.4 (1.51) pg ml(-1); 5alpha-DHT (spl) 9.7 (1.29) pg ml(-1). Except for E2beta and A in seminal plasma, a seasonal pattern was established for all other steroids with lowest mean values occurring from November to April. From the semen parameters determined, only motility was correlated to season. There was a higher correlation among oestrogen in blp than in spl and the only correlation identified between oestrogenic and androgenic steroids was between T and E2beta in blp. In spl, T was correlated with A and 5alpha-DHT. T was the dominant free steroid in bpl while it was E1 in spl; T and E1S concentrations were about 23- and 54-fold lower in spl compared to bpl with E1S, however, showing the highest absolute values in both fluids. In the fractionated ejaculate an association of free oestrogens, particularly E2beta, with spermatozoa was observed.
Publication Date: 1999-11-24 PubMed ID: 10565441DOI: 10.1016/s0378-4320(99)00050-0Google Scholar: Lookup
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Summary
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This research aims to understand the testicular function of stallions by examining the concentrations of different hormones in blood plasma and seminal plasma and their impact on the quality of semen. The study found that the concentration of these hormones displayed a seasonal pattern with the lowest mean values observed from November to April. Only the movement of sperm correlated with the season. Certain relationships exist between the oestrogenic and androgenic hormones in the different plasma.
About the Research
The study was designed to gather more in-depth information on gonadal function in stallions, specifically relating to hormonal presence and interactions in the blood and seminal plasma and their distribution across the ejaculate. Scientists collected samples from 11 stallions over a period from November to July. The hormones analyzed included Estrone (E1), Estrone sulfate (E1S), Estradiol-17beta (E2beta) and Testosterone (T) in both blood and seminal plasma. Additionally, Androstenedione (A), Dehydroepiandrosterone (DHEA) and 5alpha-dihydrotestosterone (5alpha-DHT) were only measured in seminal plasma.
Results of the Study
- All measured hormones, except for E2beta and A in seminal plasma, showed a notable seasonal pattern, with the lowest average concentration detected between November and April.
- Out of all the semen parameters surveyed, only sperm motility demonstrated a seasonal correlation.
- Stronger correlations were observed among estrogen levels in the blood plasma than in seminal plasma. A relationship between Testosterone and E2beta in the blood plasma was detected.
- In the seminal plasma, Testosterone’s correlation was with Androstenedione and 5alpha-DHT.
- Testosterone was the dominant free steroid in the blood plasma, while in the seminal plasma; it was Estrone. The concentrations of Testosterone and E1S were much lower in seminal plasma relative to blood plasma.
- When examining the fractionated ejaculate, scientists found associations of free estrogens, particularly E2beta, with spermatozoa.
Implications of Findings
The research illuminates the complexities of equine reproductive biology, more specifically in stallions. The discovery of the seasonal fluctuations of certain hormones can be a significant tool in predicting or manipulating breeding cycles. This could increase successful breeding rates and improve overall equine husbandry. Understanding the hormone interactions in the different types of plasma allows researchers to delve deeper into what controls sperm production and motility. The findings could potentially pave the way for advancements in fertility treatments for stallions.
Cite This Article
APA
Hoffmann B, Landeck A.
(1999).
Testicular endocrine function, seasonality and semen quality of the stallion.
Anim Reprod Sci, 57(1-2), 89-98.
https://doi.org/10.1016/s0378-4320(99)00050-0 Publication
Researcher Affiliations
- Klinik für Geburtshilfe, Gynäkologie und Andrologie der Gross-und Kleintiere mit Tierärztlicher Ambulanz der Justus-Liebig-Universität Giessen, Germany. bernd.hoffman@vetmed.uni-giessen.de
MeSH Terms
- Androgens / analysis
- Androgens / blood
- Androstenedione / analysis
- Animals
- Dehydroepiandrosterone / analysis
- Dihydrotestosterone / analysis
- Estradiol / analysis
- Estrogens / analysis
- Estrogens / blood
- Estrone / analogs & derivatives
- Estrone / analysis
- Horses
- Male
- Seasons
- Semen / chemistry
- Semen / physiology
- Spermatozoa / physiology
- Testis / physiology
- Testosterone / analysis
Citations
This article has been cited 15 times.- Stempel S, Körber H, Reifarth L, Schuler G, Goericke-Pesch S. What Happens in Male Dogs after Treatment with a 4.7 mg Deslorelin Implant? II. Recovery of Testicular Function after Implant Removal. Animals (Basel) 2022 Sep 23;12(19).
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- Prestel L, Joerling J, Failing K, Wagner H, Wehrend A. Suppression of reproductive function in juvenile rams by a slow-release gonadotropin-releasing hormone implant. Open Vet J 2022 Mar-Apr;12(2):171-181.
- Goericke-Pesch S, Reifarth L, Behrens Mathiesen C, Schuler G, Umbach AK, Körber H. Chronic Immune-Mediated Orchitis Is the Major Cause of Acquired Non-obstructive Azoospermia in Dogs. Front Vet Sci 2022;9:865967.
- Wyffels JT, Adams LM, Bulman F, Fustukjian A, Hyatt MW, Feldheim KA, Penfold LM. Artificial insemination and parthenogenesis in the whitespotted bamboo shark Chiloscyllium plagiosum. Sci Rep 2021 May 13;11(1):9966.
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- Gabai G, Mongillo P, Giaretta E, Marinelli L. Do Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEAS) Play a Role in the Stress Response in Domestic Animals?. Front Vet Sci 2020;7:588835.
- Chimote NM, Nath NM, Chimote NN, Chimote BN. Follicular fluid dehydroepiandrosterone sulfate is a credible marker of oocyte maturity and pregnancy outcome in conventional in vitro fertilization cycles. J Hum Reprod Sci 2015 Oct-Dec;8(4):209-13.
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- Leme DP, Papa FO, Roser JF. Reproductive characteristics of stallions during the breeding and non-breeding season in a tropical region. Trop Anim Health Prod 2012 Oct;44(7):1703-7.
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- Dziekońska A, Szczepańska A, Wysokińska A. Effect of Season on the Characteristics of Warmblood Stallion Spermatozoa Stored in a Liquid State at 5 °C. Animals (Basel) 2025 Apr 3;15(7).
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