Administration of sulpiride to anovulatory mares in winter: effects on prolactin and gonadotropin concentrations, ovarian activity, ovulation and hair shedding.
Abstract: Sixteen seasonally anovulatory mares were randomly allotted to two groups and injected daily with either sulpiride (1 mg/kg body weight) or vehicle from 14 January to 14 February. Sulpiride administration increased daily plasma prolactin concentrations (P < 0.05), although the prolactin response during the 6 h following sulpiride injections decreased markedly from the 1st to the 6th day of treatment (treatment by day, P < 0.0001). Plasma concentrations of LH and FSH were not affected by treatment (P > 0.1). Injection of GnRH and TRH on 15 February showed that the response of plasma prolactin to secretagogue was increased in sulpiride-treated mares (P < 0.005), while there was no effect (P > 0.1) of sulpiride treatment on the response of LH or FSH. Both treatment groups had similar changes in numbers of follicles 10-19 and > or = 20 mm during the experiment (P > 0.1). Similarly, the mean change in maximal follicular size was not affected by treatment (P > 0.9). No mare ovulated during the study, and plasma progesterone concentrations were similar in both groups (P > 0.1), always at levels < 1 ng/ml. Hairshedding increased with time in all mares (P < 0.001) and was increased by sulpiride injections (P = 0.09). It was concluded that sulpiride administration to seasonally anovulatory mares under the conditions of our experiment increased daily plasma prolactin levels but did not stimulate gonadotropin secretion or ovarian activity.
Publication Date: 2002-05-10 PubMed ID: 11998830DOI: 10.1016/s0093-691x(01)00696-3Google Scholar: Lookup
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- Clinical Trial
- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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The research study investigates the effects of the drug sulpiride on various hormone levels, ovarian activity and hair shedding in unmated female horses, finding it increased the plasma prolactin but did not stimulate ovarian activity or gonadotropin secretion.
Research Methodology
- The study involved sixteen seasonal anovulatory (non-mating) mares which were randomly divided into two groups.
- One group was injected with sulpiride (1 mg/kg body weight) daily, while the other group was given a vehicle injection for comparison.
- The injections were authored from January 14th to February 14th.
Observation & Findings
- The administration of sulpiride was observed to increase daily plasma prolactin concentrations significantly. However, the prolactin response following sulpiride injections notably decreased from the 1st to the 6th day of treatment.
- There was no significant effect noted on the plasma concentrations of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) due to the treatment.
- When injected with Gonadotropin-Releasing Hormone (GnRH) and Thyrotropin-Releasing Hormone (TRH), the response of plasma prolactin increased in sulpiride treated mares, but no effect of the drug was observed on the response of LH or FSH.
- Both groups exhibited similar changes in the numbers of follicles of various sizes throughout the experiment.
- No mare in the study ovulated and the concentration of plasma progesterone remained similar in both groups.
- Hair shedding increased over time in all study subjects, with a slight increase noted in the sulpiride treated group.
Conclusion
- The study concludes that under the conducted experimental conditions, administering sulpiride to anovulatory mares increases daily prolactin levels in the plasma but does not stimulate the secretion of gonadotropins or activate ovarian activity.
- This may suggest that the role of prolactin in reproductive processes is likely complex and should be further studied, considering sulpiride treatment did not lead to ovulation or any significant changes in gonadotropin levels.
Cite This Article
APA
Donadeu FX, Thompson DL.
(2002).
Administration of sulpiride to anovulatory mares in winter: effects on prolactin and gonadotropin concentrations, ovarian activity, ovulation and hair shedding.
Theriogenology, 57(2), 963-976.
https://doi.org/10.1016/s0093-691x(01)00696-3 Publication
Researcher Affiliations
- Department of Animal Science, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
MeSH Terms
- Animals
- Anovulation
- Dopamine Antagonists / administration & dosage
- Female
- Follicle Stimulating Hormone / blood
- Gonadotropin-Releasing Hormone / administration & dosage
- Gonadotropins / blood
- Hair / drug effects
- Hair / physiology
- Horses / physiology
- Kinetics
- Luteinizing Hormone / blood
- Ovarian Follicle / anatomy & histology
- Ovary / diagnostic imaging
- Ovary / drug effects
- Ovary / physiology
- Ovulation / drug effects
- Placebos
- Progesterone / blood
- Prolactin / blood
- Seasons
- Sulpiride / administration & dosage
- Thyrotropin-Releasing Hormone / administration & dosage
- Ultrasonography
Citations
This article has been cited 3 times.- Fanelli D, Tesi M, Rota A, Beltramo M, Conte G, Giorgi M, Barsotti G, Camillo F, Panzani D. hCG is more effective than the GnRH agonist buserelin for inducing the first ovulation of the breeding season in mares. Equine Vet J 2022 Mar;54(2):306-311.
- Suzuki T, Mizukami H, Nambo Y, Ishimaru M, Miyata K, Akiyama K, Korosue K, Naito H, Nagaoka K, Watanabe G, Taya K. Different effects of an extended photoperiod treatment on growth, gonadal function, and condition of hair coats in Thoroughbred yearlings reared under different climate conditions. J Equine Sci 2015;26(4):113-24.
- Kunii H, Nambo Y, Okano A, Matsui A, Ishimaru M, Asai Y, Sato F, Fujii K, Nagaoka K, Watanabe G, Taya K. Effects of an extended photoperiod on gonadal function and condition of hair coats in Thoroughbred colts and fillies. J Equine Sci 2015;26(2):57-66.
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