Systemic relaxin in pregnant pony mares grazed on endophyte-infected fescue: effects of fluphenazine treatment.
Abstract: Tall fescue is one of the most widely grown forage grasses for horses in the United States. However, it is frequently infected with the endophyte Neotyphodium coenophialum which produces ergot alkaloids that cause severe adverse effects in the pregnant mare. The objectives of this study were to determine the effects of fescue toxicosis and fluphenazine on circulating relaxin in pregnant pony mares and evaluate the usefulness of relaxin as a monitor of treatment efficacy. Twelve mares were maintained on endophyte-infected tall fescue pasture. Group TRT (n = 6), received 25 mg of fluphenazine decanoate (i.m.) on Day 320 of gestation while Group UTRT served as untreated controls. Daily blood samples were collected from Day 300 of gestation until Day 3 post partum and analyzed for plasma relaxin concentrations using a homologous equine radioimmunoassay. Mean gestation lengths were 330 +/- 0.7 and 336.5 +/- 3.2 days for TRT and UTRT mares, respectively (P = 0.07). Mean plasma relaxin concentrations in both groups of mares during the week before treatment (Day 313 to 319) were not different (UTRT, 53.4 +/- 11.3 ng/mL; TRT, 61.4 +/- 9.3 ng/mL). In the week after treatment (Day 320 to 326), mean plasma relaxin tended to be higher (P = 0.1) in TRT mares (66.7 +/- 6.2 ng/mL) when compared with UTRT mares (49.6 +/- 6.6 ng/mL), representing a 17.1 ng/mL difference in circulating relaxin between the two groups. Systemic relaxin during the last week before delivery (days relative to parturition) for UTRT and TRT mares was 45.7 +/- 6.7 and 64.7 +/- 6.4 ng/mL (P = 0.06), respectively. At Day -8 and Day -5 relative to parturition, systemic relaxin in TRT mares was significantly higher (P < 0.05) than in UTRT mares. Three of the six UTRT mares and one TRT mare showed clinical symptoms of fescue toxicosis. In the week before delivery, circulating relaxin in mares with problematic pregnancies (39.9 +/- 7.8 ng/mL) was significantly lower than concentrations measured in mares with normal pregnancies (63.4 +/- 5.4 ng/mL; P = 0.03). Clinical observations suggest that a one-time injection with fluphenazine improved pregnancy outcome by reducing the adverse effects of fescue toxicosis concomitant with a stabilization of plasma relaxin concentrations. These data support the hypothesis that systemic relaxin may be a useful biochemical means of monitoring placental function and treatment efficacy in the mare.
Publication Date: 2001-08-23 PubMed ID: 11516126DOI: 10.1016/s0093-691x(01)00578-7Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research studies the influence of fescue toxicosis and drug treatment, specifically fluphenazine, on the circulating hormone relaxin in pregnant pony mares, and explores the potential of relaxin as an indicator of treatment efficiency. The toxicosis is caused by their graze endophyte-infected fescue grass.
Study Design and Concern
- The study was undertaken in an attempt to understand how fescue toxicosis (caused by the ingestion of endophyte-infected tall fescue) and fluphenazine affect the levels of the hormone relaxin in pregnant pony mares. It also considered relaxin, a hormone involved in various stages of pregnancy, as a possible indicator of effective treatment of the toxicosis.
- 12 pony mares were used for the study. All the mares were kept on pastures of endophyte-infected tall fescue; six of them (TRT group) were given 25mg of fluphenazine on the 320th day of their gestation period while the remaining six (UTRT group) served as untreated controls. Blood samples of the mares were collected from the 300th day of gestation until the third day post-partum for analyzing relaxin concentrations.
Results and Observations
- The research found that the gestation period is marginally extended, from 330 days to 336.5 days in untreated mares when compared to the treated group, but this was not statistically significant.
- A week before treatment, the concentration of relaxin in treated and untreated mares was very similar. The week following treatment, however, saw a slightly higher mean of relaxin concentration in the treated group when compared with the untreated group; this figure is not statistically significant as well.
- The relaxin level in TRT mares was significantly higher than in untreated mares on the 8th and 5th day relative to parturition, suggesting the treatment stabilized relaxin concentration. A lower relaxin level was noticed in mares with complicated pregnancies in comparison to mares with normal pregnancies.
- From a clinical observation standpoint, three untreated mares and one treated mare showed symptoms of fescue toxicosis.
Impication and Conclusion
- The research concludes that fluphenazine not only controlled the adverse effects of fescue toxicosis but also stabilized the relaxin concentration in the blood. This observation led to the hypothesis that relaxin levels could be used as a biochemical means to monitor placental function and the efficacy of the toxicosis treatment.
- These findings are important as they offer potential pathways for improving the management of pregnant mares in terms of their health and the quality of pregnancy outcomes – particularly those grazing on endophyte-infected tall fescue.
Cite This Article
APA
Ryan PL, Bennett-Wimbush K, Vaala WE, Bagnell CA.
(2001).
Systemic relaxin in pregnant pony mares grazed on endophyte-infected fescue: effects of fluphenazine treatment.
Theriogenology, 56(3), 471-483.
https://doi.org/10.1016/s0093-691x(01)00578-7 Publication
Researcher Affiliations
- Department of Molecular Biology, Princeton University, NJ, USA. pryan@ads.msstate.edu
MeSH Terms
- Acremonium
- Animals
- Dopamine Antagonists / administration & dosage
- Dopamine Antagonists / pharmacology
- Ergotism / blood
- Ergotism / drug therapy
- Ergotism / veterinary
- Female
- Fluphenazine / administration & dosage
- Fluphenazine / pharmacology
- Horse Diseases / blood
- Horse Diseases / drug therapy
- Horses
- Placental Insufficiency / blood
- Placental Insufficiency / etiology
- Poaceae / microbiology
- Pregnancy
- Pregnancy Complications / blood
- Pregnancy Complications / drug therapy
- Pregnancy Complications / veterinary
- Random Allocation
- Relaxin / blood
Citations
This article has been cited 3 times.- Schuler G, Fürbass R, Klisch K. Placental contribution to the endocrinology of gestation and parturition. Anim Reprod 2018 Jul-Sep;15(Suppl 1):822-842.
- Fayrer-Hosken R, Stanley A, Hill N, Heusner G, Christian M, De La Fuente R, Baumann C, Jones L. Effect of feeding fescue seed containing ergot alkaloid toxins on stallion spermatogenesis and sperm cells. Reprod Domest Anim 2012 Dec;47(6):1017-26.
- Feugang JM, Rodriguez-Munoz JC, Willard ST, Bathgate RA, Ryan PL. Examination of relaxin and its receptors expression in pig gametes and embryos. Reprod Biol Endocrinol 2011 Jan 20;9:10.
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