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Effects of the Glucosinolate Sinigrin in Combination With a Noniodine Supplemented Diet on Serum Iodine and Thyroid Hormone Concentrations in Nonpregnant Mares. J Equine Vet Sci 2020; 91:103110. [PMID: 32684255 DOI: 10.1016/j.jevs.2020.103110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/20/2020] [Accepted: 04/20/2020] [Indexed: 01/07/2023]
Abstract
Exposure to plants containing glucosinolates (GSLs) affects thyroid function in many species, in horses is implicated in the birth of foals with congenital hypothyroidism. The present study was performed to determine the effect of feeding a GSL (sinigrin) in combination with a low-iodine diet for 12 weeks on thyroid hormones and serum iodine concentrations in nonpregnant mares. Nineteen mares aged 2-14 years were divided into control (n = 6), low (20 mmol/day) (n = 7) and high GSL (35 mmol/day) (n = 6) groups. Thyrotropin-releasing hormone (TRH) stimulation tests and serum iodine measurements were performed at 0 and 12 weeks. Total triiodothyronine (TT3), total thyroxine (TT4), and thyroid-stimulating hormone (TSH) concentrations were measured at the baseline and in post-TRH samples. The post-TRH value minus the basal value (Delta Δ) and fold change (FC) were calculated for TSH, TT3, and TT4. Data were analyzed at P < .05. Highlights included Delta Δ and FC TT4 and TT3 concentrations having a group and week interaction (P < .001) with week 12 control mares having higher values than mares in week 12 low and high GSL groups. TT4 FC values had a group (P < .001) and group by week interaction (P < .001) with week 12 control concentrations higher (P < .006) than all groups. Iodine concentrations decreased (P < .002) over time in GSL mares. In conclusion, feeding mares a low-iodine diet with 20 and 35 mmol sinigrin/day resulted in lower serum iodine concentrations.
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Tangyuenyong S, Nambo Y, Nagaoka K, Tanaka T, Watanabe G. Sensitive radioimmunoassay of total thyroxine (T4) in horses using a simple extraction method. J Vet Med Sci 2017; 79:1294-1300. [PMID: 28603213 PMCID: PMC5559379 DOI: 10.1292/jvms.17-0133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Most thyroid hormone determinations in animals are based on immunoassays adapted from those used to test human samples, which may not reflect the actual values of thyroid hormone in horses because of the presence of binding proteins. The aims of the present study were i) to establish a novel radioimmunoassay (RIA) using a more simple and convenient method to separate binding proteins for the measurement of total thyroxine (T4) in horses and ii) to validate the assay by comparing total T4 concentrations in yearling horses raised in different climates. Blood samples were collected from trained yearlings in Hokkaido (temperate climate) and Miyazaki (subtropical climate) in Japan and from adult horses in estrus and diestrus. T4 was extracted from both serum and plasma using modified acid ethanol cryo-precipitation and sodium acetate ethanol methods. Circulating total T4 concentrations were determined by RIA. T4 concentration by sodium acetate ethanol was appropriately detectable rather than sodium salicylate method and was the same as for acid ethanol method. Furthermore, this sodium acetate ethanol method required fewer extraction steps than the other methods. Circulating T4 concentrations in yearlings were 225.98 ± 20.89 ng/ml, which was higher than the previous reference values. With respect to climate, T4 levels in Hokkaido yearlings tended to be higher than those in Miyazaki yearlings throughout the study period. These results indicated that this RIA protocol using a modified sodium acetate ethanol separation technique might be an appropriate tool for specific measurement of total T4 in horses.
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Affiliation(s)
- Siriwan Tangyuenyong
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Yasuo Nambo
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-0834, Japan
| | - Kentaro Nagaoka
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Tomomi Tanaka
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Reproduction, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Gen Watanabe
- Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.,Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
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Fazio E, Medica P, Cravana C, Ferlazzo A. Comparative Effects of Simulated and Conventional Transportations on the Thyroid Response of Stallions (Equus caballus). J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2015.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Fazio E, Medica P, Cravana C, Pellizzotto R, Fragalà S, Ferlazzo A. Dynamics of Total and Free Iodothyronines of Jumping Horses on the Responses to Competition and Transport. J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2014.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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