A Thyroid Hormone Challenge in Hypothyroid Rats Identifies T3 Regulated Genes in the Hypothalamus and in Models with Altered Energy Balance and Glucose Homeostasis

Annika Herwig, Gill Campbell, Claus-Dieter Mayer, Anita Boelen, Richard A Anderson, Alexander W Ross, Julian G Mercer, Perry Barrett

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Background: The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. Methods: Sprague Dawley rats were made hypothyroid by giving 0.025% methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. Results: Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (±1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. Conclusion: This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.

Original languageEnglish
Pages (from-to)1575-1593
Number of pages19
JournalThyroid : official journal of the American Thyroid Association
Volume24
Issue number11
DOIs
Publication statusPublished - 2 Sep 2014

Fingerprint

Thyroid Hormones
Hypothalamus
Homeostasis
Glucose
Genes
In Situ Hybridization
Body Weight
Triiodothyronine
Microarray Analysis
Body Composition
Gene Expression
Brain
Eating
Methimazole
Thyrotropin
Therapeutics
Glucose Tolerance Test
Nonesterified Fatty Acids
Drinking Water
Sprague Dawley Rats

Cite this

@article{f6352c1c00764befb80ed1c66753f84d,
title = "A Thyroid Hormone Challenge in Hypothyroid Rats Identifies T3 Regulated Genes in the Hypothalamus and in Models with Altered Energy Balance and Glucose Homeostasis",
abstract = "Background: The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. Methods: Sprague Dawley rats were made hypothyroid by giving 0.025{\%} methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. Results: Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (±1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. Conclusion: This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.",
author = "Annika Herwig and Gill Campbell and Claus-Dieter Mayer and Anita Boelen and Anderson, {Richard A} and Ross, {Alexander W} and Mercer, {Julian G} and Perry Barrett",
note = "Acknowledgments This work was supported by PIEF-GA-2009-235106 Marie Curie individual fellowship and HE 6383/1-1 EmmyNoether fellowship to Annika Herwig and further funding from the Scottish Government Rural and Environment Science and Analytical Services Division. We thank Jenny Morris and Pete Hedley of the Genome Technology group, James Hutton Institute, Dundee, for help in scanning the Agilent arrays, Dana Wilson for laboratory assistance, and Vivian Buchan and Donna Henderson for analysis of serum concentrations of glucose, NEFAs, and triglycerides.",
year = "2014",
month = "9",
day = "2",
doi = "10.1089/thy.2014.0169",
language = "English",
volume = "24",
pages = "1575--1593",
journal = "Thyroid : official journal of the American Thyroid Association",
issn = "1557-9077",
publisher = "Mary Ann Liebert Inc.",
number = "11",

}

TY - JOUR

T1 - A Thyroid Hormone Challenge in Hypothyroid Rats Identifies T3 Regulated Genes in the Hypothalamus and in Models with Altered Energy Balance and Glucose Homeostasis

AU - Herwig, Annika

AU - Campbell, Gill

AU - Mayer, Claus-Dieter

AU - Boelen, Anita

AU - Anderson, Richard A

AU - Ross, Alexander W

AU - Mercer, Julian G

AU - Barrett, Perry

N1 - Acknowledgments This work was supported by PIEF-GA-2009-235106 Marie Curie individual fellowship and HE 6383/1-1 EmmyNoether fellowship to Annika Herwig and further funding from the Scottish Government Rural and Environment Science and Analytical Services Division. We thank Jenny Morris and Pete Hedley of the Genome Technology group, James Hutton Institute, Dundee, for help in scanning the Agilent arrays, Dana Wilson for laboratory assistance, and Vivian Buchan and Donna Henderson for analysis of serum concentrations of glucose, NEFAs, and triglycerides.

PY - 2014/9/2

Y1 - 2014/9/2

N2 - Background: The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. Methods: Sprague Dawley rats were made hypothyroid by giving 0.025% methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. Results: Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (±1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. Conclusion: This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.

AB - Background: The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. Methods: Sprague Dawley rats were made hypothyroid by giving 0.025% methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. Results: Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (±1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. Conclusion: This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.

U2 - 10.1089/thy.2014.0169

DO - 10.1089/thy.2014.0169

M3 - Article

VL - 24

SP - 1575

EP - 1593

JO - Thyroid : official journal of the American Thyroid Association

JF - Thyroid : official journal of the American Thyroid Association

SN - 1557-9077

IS - 11

ER -