Prolactin involvement with the increase in seminal volume after sexual stimulation in stallions.
Abstract: To test the hypothesis that prolactin mediates the increase in seminal volumes induced by sexual stimulation in stallions, semen was collected from six stallions every other day for 26 d. The last eight collection days were treatment days. For each stallion, four treatments were randomly assigned to the first four of the eight treatment collection days, and then repeated in reverse order on the last four collection days; 1) CONTROL: semen collected per normal procedures; 2) Sexually stimulated: stallions were presented to mares in a chute for 10 min before collection; 3) Bromocriptine (dopamine agonist) plus sexual stimulation: stallions were administered bromocriptine 10 min before 10 min of sexual stimulation prior to collection; and 4) Sulpiride: stallions were administered sulpiride (a dopamine antagonist) 25 min before collection. Prolactin concentrations in plasma were increased by sexual stimulation (P < .01) and sulpiride (P < .001) administration and were decreased (P < .01) when bromocriptine was administered before sexual stimulation. Sexual stimulation alone increased (P < .01) volume of gel-free semen relative to control values (102 vs 81 mL), and bromocriptine prevented this response (89 mL; P < .075 relative to sexual stimulation). Sulpiride had no effect (P > .1) on gel-free volume. Volume of gelatinous material, number of mounts, sperm concentration, motility, pH of gel-free semen, number of spermatozoa per ejaculate, and prolactin concentration in gel-free semen were not affected (P > .1) by treatment. Although the effect of bromocriptine indicated that prolactin may mediate the rise in seminal volume due to sexual stimulation, if it does, it must be in conjunction with other hormone(s) or factor(s), because increasing prolactin concentrations alone did not increase seminal volume in these stallions.
Publication Date: 1996-10-01 PubMed ID: 8904716DOI: 10.2527/1996.74102468xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article examines how a hormone called prolactin could be linked to the increase in volume of semen in stallions induced by sexual stimulation.
Research Methodology
- The study was conducted on six stallions over a span of 26 days. Every other day, semen was collected from these stallions.
- The experiment assigned four different treatments to the stallions, namely normal condition, sexual stimulation, combination of sexual stimulation and bromocriptine (a dopamine agonist), and sulpiride (a dopamine antagonist).
- Control treatment involved the collection of semen under normal conditions. For sexual stimulation treatment, stallions were presented to mares for a period of 10 minutes before the semen collection. In the third treatment, stallions were given bromocriptine 10 minutes before the sexual stimulation. Finally, in the fourth treatment, sulpiride was administered 25 minutes before the semen collection.
Findings
- The concentration of prolactin in the stallion’s plasma increased after sexual stimulation and sulpiride administration while bromocriptine administration before sexual stimulation decreased the prolactin concentration.
- Seminal volumes were found to increase after sexual stimulation when compared to control values, and this increase was prevented by the administration of bromocriptine.
- The application of sulpiride had no effect on the volume of the semen without gelatinous material.
- The study found no effect on factors such as volume of gelatinous material, number of mounts, sperm concentration, motility, pH of semen, number of spermatozoa per ejaculate, and prolactin concentration in semen without the gelatinous material due to the treatments.
Conclusions
- The results suggest that prolactin might be involved in the increase in semen volume post sexual stimulation. This is indicated by the fact that blocking prolactin with bromocriptine prevented the increase in semen volume.
- However, the researchers note that if prolactin does mediate this process, it might be working in conjunction with some other hormone or factor. This conclusion is based on the observation that increasing prolactin concentration alone did not increase the seminal volume in the stallions.
Cite This Article
APA
Thomson CH, Thompson DL, Kincaid LA, Nadal MR.
(1996).
Prolactin involvement with the increase in seminal volume after sexual stimulation in stallions.
J Anim Sci, 74(10), 2468-2472.
https://doi.org/10.2527/1996.74102468x Publication
Researcher Affiliations
- Department of Animal Science, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
MeSH Terms
- Animals
- Bromocriptine / pharmacology
- Dopamine Agonists / pharmacology
- Dopamine Antagonists / pharmacology
- Dose-Response Relationship, Drug
- Horses / metabolism
- Horses / physiology
- Male
- Prolactin / antagonists & inhibitors
- Prolactin / blood
- Prolactin / physiology
- Random Allocation
- Semen / cytology
- Semen / metabolism
- Sexual Behavior, Animal / physiology
- Sperm Count
- Sperm Motility
- Sulpiride / pharmacology
- Time Factors
Citations
This article has been cited 1 times.- Wilson M, Williams J, Montrose VT, Williams J. Variance in Stallion Semen Quality among Equestrian Sporting Disciplines and Competition Levels. Animals (Basel) 2019 Jul 25;9(8).
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