The Wolff–Chaikoff effect ameliorates heat stress in rats

Abstract Background The thyroid gland contributes immensely to the basal metabolic rate, and hence, thermogenesis in mammals. Its response to the thermal environment is, however, slow and may require several days to adjust. A rapid thyrosuppressive mechanism (“Wolff–Chaikoff” phenomenon; WC) is indu...

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Main Authors: Hosam J. Al-Tamimi, Amani Al-Dawood, Zainab Mahasneh
Format: Article
Language:English
Published: BMC 2019-04-01
Series:Animal Biotelemetry
Subjects:
Online Access:http://link.springer.com/article/10.1186/s40317-019-0170-x
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author Hosam J. Al-Tamimi
Amani Al-Dawood
Zainab Mahasneh
author_facet Hosam J. Al-Tamimi
Amani Al-Dawood
Zainab Mahasneh
author_sort Hosam J. Al-Tamimi
collection DOAJ
description Abstract Background The thyroid gland contributes immensely to the basal metabolic rate, and hence, thermogenesis in mammals. Its response to the thermal environment is, however, slow and may require several days to adjust. A rapid thyrosuppressive mechanism (“Wolff–Chaikoff” phenomenon; WC) is inducible by high dietary iodine ingestion. The current study aimed to examine the WC on thermophysiology of rats exposed to acute heat stress (HS). Biotelemetry was used to assess real-time core body temperature (T core), locomotive activity (LA) and heart rate (HR) in rats (N = 12). Animals were randomly assigned to two treatment groups: a control (CN) group had ad libitum access to tap water throughout the trial; a second group (KI) received potassium iodide (0.5%) in drinking water, 3 h before HS. Climatic conditions during the 10-day experimental period were set to 4 days at thermoneutrality (TN; T a = 23.60 ± 0.05 °C), then HS (T a = 33.22 ± 0.25 °C, for 4 h) and finally back to TN until the end of trial. Serum samples were collected right after the HS, to measure free thyroxine (FT4), triiodothyronine (FT3) and total antioxidant capacity (TAO), from 12 other equivalent rats. Results The KI induced the WC, as evidenced with lower FT3 (1.66 and 1.91 ± 0.08 pg/mL) than the CN treatment, respectively. This momentary goitrogenic response by KI mitigated hyperthermia, compared to CN (T core maxima of 38.90 and 39.54 ± 0.09 °C). Furthermore, KI resulted in higher TAO than KI-free rats (238.30 and 198.80 ± 9.10 µM copper reducing equivalents). While instigating an instant suppression in LA, KI caused a delayed 25% elevation in HR along with a rebound in T core, likely due to the “escape phenomenon.” Conclusions The employed WC protocol alleviated HS impact on rats. Research on other mammals awaits further investigation.
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spelling doaj.art-fb6fb62012d942ecb40d8264f92b10162022-12-21T18:54:52ZengBMCAnimal Biotelemetry2050-33852019-04-01711710.1186/s40317-019-0170-xThe Wolff–Chaikoff effect ameliorates heat stress in ratsHosam J. Al-Tamimi0Amani Al-Dawood1Zainab Mahasneh2Department of Animal Science, Jordan University of Science and TechnologyDepartment of Applied Biology, Tafila Technical UniversityDepartment of Animal Science, Jordan University of Science and TechnologyAbstract Background The thyroid gland contributes immensely to the basal metabolic rate, and hence, thermogenesis in mammals. Its response to the thermal environment is, however, slow and may require several days to adjust. A rapid thyrosuppressive mechanism (“Wolff–Chaikoff” phenomenon; WC) is inducible by high dietary iodine ingestion. The current study aimed to examine the WC on thermophysiology of rats exposed to acute heat stress (HS). Biotelemetry was used to assess real-time core body temperature (T core), locomotive activity (LA) and heart rate (HR) in rats (N = 12). Animals were randomly assigned to two treatment groups: a control (CN) group had ad libitum access to tap water throughout the trial; a second group (KI) received potassium iodide (0.5%) in drinking water, 3 h before HS. Climatic conditions during the 10-day experimental period were set to 4 days at thermoneutrality (TN; T a = 23.60 ± 0.05 °C), then HS (T a = 33.22 ± 0.25 °C, for 4 h) and finally back to TN until the end of trial. Serum samples were collected right after the HS, to measure free thyroxine (FT4), triiodothyronine (FT3) and total antioxidant capacity (TAO), from 12 other equivalent rats. Results The KI induced the WC, as evidenced with lower FT3 (1.66 and 1.91 ± 0.08 pg/mL) than the CN treatment, respectively. This momentary goitrogenic response by KI mitigated hyperthermia, compared to CN (T core maxima of 38.90 and 39.54 ± 0.09 °C). Furthermore, KI resulted in higher TAO than KI-free rats (238.30 and 198.80 ± 9.10 µM copper reducing equivalents). While instigating an instant suppression in LA, KI caused a delayed 25% elevation in HR along with a rebound in T core, likely due to the “escape phenomenon.” Conclusions The employed WC protocol alleviated HS impact on rats. Research on other mammals awaits further investigation.http://link.springer.com/article/10.1186/s40317-019-0170-xHeat stressRatIodineThyroidWolff–ChaikoffBiotelemetry
spellingShingle Hosam J. Al-Tamimi
Amani Al-Dawood
Zainab Mahasneh
The Wolff–Chaikoff effect ameliorates heat stress in rats
Animal Biotelemetry
Heat stress
Rat
Iodine
Thyroid
Wolff–Chaikoff
Biotelemetry
title The Wolff–Chaikoff effect ameliorates heat stress in rats
title_full The Wolff–Chaikoff effect ameliorates heat stress in rats
title_fullStr The Wolff–Chaikoff effect ameliorates heat stress in rats
title_full_unstemmed The Wolff–Chaikoff effect ameliorates heat stress in rats
title_short The Wolff–Chaikoff effect ameliorates heat stress in rats
title_sort wolff chaikoff effect ameliorates heat stress in rats
topic Heat stress
Rat
Iodine
Thyroid
Wolff–Chaikoff
Biotelemetry
url http://link.springer.com/article/10.1186/s40317-019-0170-x
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