Evaluation of a thyrotropin-releasing hormone solution stored at room temperature for pituitary pars intermedia dysfunction testing in horses.
Abstract: To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at -20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH). Methods: 34 adult horses. Methods: The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the second test (group 2), and 10 horses were administered rTRH for both tests (group 3). Plasma ACTH concentrations were measured at 0 (baseline) and 30 minutes after TRH administration and the delta ACTH responses (change in ACTH concentration after TRH administration) were calculated. In experiment 2, the design was the same as that for experiment 1 except there were 14 days between tests, ACTH was measured at 0 and 10 minutes after TRH administration, and 11, 9, and 10 horses were assigned to groups 1, 2, and 3, respectively. Results: Adverse effects associated with TRH administration included transient coughing and yawning. In experiment 1, the median delta ACTH response for the second test was significantly lower than that for the first test for all groups. In experiment 2, the median delta ACTH response did not differ significantly between the first and second tests for any group, ACTH concentrations after rTRH administration were positively correlated (rs = 0.95) with those after cTRH administration, and the mean ± SD bias in post-TRH ACTH concentration between rTRH and cTRH was 2.9 ± 12.4 pg/mL. Conclusions: Results indicated that the TRH stimulation test should not be repeated within 24 hours, and cTRH solution stored at room temperature could be used to effectively perform TRH stimulation testing in horses.
Publication Date: 2015-04-25 PubMed ID: 25909376DOI: 10.2460/ajvr.76.5.437Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study aimed to establish if plasma ACTH levels in horses change when administered a thyrotropin-releasing hormone (TRH) solution prepared under different conditions. The research concluded that the TRH test shouldn’t be repeated within 24 hours, and a TRH solution stored at room temperature could be effectively used for the stimulation testing in horses.
Research Methodology
The research comprised of two separate but similar experiments, both focusing on evaluating the variation in plasma ACTH (Adrenocorticotropic hormone) concentrations in horses following the introduction of TRH solutions, prepared and stored differently. TRH is a hormone that aids in the release of the thyroid-stimulating hormone and prolactin.
- In the first experiment, thirty horses were divided into three groups. Each horse went through two TRH stimulation tests with a 24 hours gap. The difference was in the preparation and storage condition of the TRH solution. One group received a TRH solution prepared by a compounding pharmacy and stored at room temperature (cTRH), another prepared for research purposes and stored at -20°C (rTRH) while the third group got rTRH for both tests.
- In the second experiment, the researchers followed a design similar to the first experiment, but with a longer gap of 14 days between tests. They also altered the number of horses in each group.
Findings
- Some horses showed mild, transient effects such as temporary coughing and yawning, following the administration of the TRH solutions.
- In the first experiment, the median delta ACTH (change in ACTH concentration post-TRH administration) responses for the second test was significantly lower than that of the first test for all groups, suggesting the TRH stimulation test should not be repeated within 24 hours.
- In the second experiment, the median delta ACTH response did not display a significant difference between the first and second tests for any group, indicating that the 14 days gap between tests may have mitigated the difference observed in the first experiment.
- The research also noted a positive correlation (rs = 0.95) between ACTH concentrations after rTRH and cTRH administration, meaning the preparation and storage conditions of the TRH solutions had little impact on the outcomes.
- The mean ± SD bias (average difference between measures) in post-TRH ACTH concentration between rTRH and cTRH was 2.9 ± 12.4 pg/mL, which is not significant, leading to the conclusion that cTRH solution stored at room temperature could be effectively used for TRH stimulation testing in horses.
Cite This Article
APA
Goodale L, Frank N, Hermida P, D'Oench S.
(2015).
Evaluation of a thyrotropin-releasing hormone solution stored at room temperature for pituitary pars intermedia dysfunction testing in horses.
Am J Vet Res, 76(5), 437-444.
https://doi.org/10.2460/ajvr.76.5.437 Publication
Researcher Affiliations
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
MeSH Terms
- Administration, Intravenous / veterinary
- Adrenocorticotropic Hormone / blood
- Animals
- Female
- Horses / metabolism
- Male
- Pituitary Gland, Intermediate / metabolism
- Temperature
- Thyrotropin-Releasing Hormone / blood
- Veterinary Medicine / methods
Citations
This article has been cited 5 times.- Thane K, Uricchio C, Frank N. Effect of early or late blood sampling on thyrotropin releasing hormone stimulation test results in horses. J Vet Intern Med 2022 Mar;36(2):770-777.
- Fortin JS, Hetak AA, Duggan KE, Burglass CM, Penticoff HB, Schott HC 2nd. Equine pituitary pars intermedia dysfunction: a spontaneous model of synucleinopathy. Sci Rep 2021 Aug 6;11(1):16036.
- Horn R, Bertin FR. Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses. J Vet Intern Med 2019 Sep;33(5):2249-2256.
- Spelta CW. Equine pituitary pars intermedia dysfunction: current perspectives on diagnosis and management. Vet Med (Auckl) 2015;6:293-300.
- Menzies-Gow NJ. Equine Pituitary Pars Intermedia Dysfunction. Vet Sci 2025 Aug 20;12(8).
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