scholarly journals Transthyretin is not necessary for thyroid hormone metabolism in conditions of increased hormone demand

2005 ◽  
Vol 187 (2) ◽  
pp. 257-266 ◽  
Author(s):  
J C Sousa ◽  
G Morreale de Escobar ◽  
P Oliveira ◽  
M J Saraiva ◽  
J A Palha
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Stressful Events ◽  
Mrna Levels ◽  
Wild Type ◽  
Hormone Metabolism ◽  
Normal Thyroid ◽  
Hormone Synthesis ◽  
Thyroid Hormone Metabolism ◽  
Hormone Homeostasis

Thyroid hormones circulate in blood mainly bound to plasma proteins. Transthyretin is the major thyroxine plasma carrier in mice. Studies in transthyretin-null mice revealed that the absence of transthyretin results in euthyroid hypothyroxinemia and normal thyroid hormone tissue distribution, with the exception of the choroid plexus in the brain. Therefore, transthyretin does not influence normal thyroid hormone homeostasis under standard laboratory conditions. To investigate if transthyretin has a buffer/storage role we challenged transthyretin-null and wild-type mice with conditions of increased hormone demand: (i) exposure to cold, which elicits thermogenesis, a process that requires thyroid hormones; and (ii) thyroidectomy, which abolishes thyroid hormone synthesis and secretion and induces severe hypothyroidism. Transthyretin-null mice responded as the wild-type both to changes induced by stressful events, namely in body weight, food intake and thyroid hormone tissue content, and in the mRNA levels of genes whose expression is altered in such conditions. These results clearly exclude a role for transthyretin in thyroid hormone homeostasis even under conditions of increased hormone demand.

Meal-induced brown fat thermogenesis and thyroid hormone metabolism in rats

1985 ◽  
Vol 249 (5) ◽  
pp. E519-E524 ◽  
Author(s):  
Z. Glick ◽  
S. Y. Wu ◽  
J. Lupien ◽  
R. Reggio ◽  
G. A. Bray ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Serum Concentrations ◽  
Hormone Metabolism ◽  
Thyroid Hormone Metabolism ◽  
Low Protein ◽  
Bat Mitochondria ◽  
Brown Adipose ◽  
Serum T3 ◽  
The Relationship

The relationship between the meal-induced increase in brown adipose tissue (BAT) thermogenesis, determined by the level of GDP binding to BAT mitochondria, and thyroid hormone metabolism have been examined. A single low-protein, high-carbohydrate meal resulted in a significant increase in the thermogenic activity of BAT. This effect on BAT thermogenesis was accompanied by significant increases in activity of thyroxine 5'-monodeiodinase in the BAT (P less than 0.05) and liver (P less than 0.02) but not with any significant changes in serum concentrations of the thyroid hormones. The stimulatory effects of the meal on BAT thermogenesis and hepatic thyroxine (T4) to triiodothyronine (T3) conversion persisted at least as late as 24 h after meal onset. Food deprivation for 40 h was associated with large reductions in serum concentrations of T3 (P less than 0.01) and T4 (P less than 0.001), but deprivation for 18 h had no significant effect on serum T3 and T4 concentrations. Our data indicate that the meal-induced increase in BAT thermogenesis can be independent from changes in serum concentrations of thyroid hormones and suggest that T3 produced in BAT in response to feeding may play a role in the thermic response of this tissue to meals.

scholarly journals Progesterone regulates hypothalamic-pituitary-thyroid axis

2017 ◽  
Author(s):  
Chunyun Zhong ◽  
Kewen Xiong ◽  
Xin Wang
Keyword(s):  
Thyroid Hormone ◽  
Aquatic Ecosystems ◽  
Endocrine System ◽  
Hormone Metabolism ◽  
Hormone Synthesis ◽  
Thyroid Hormone Metabolism ◽  
Expression Of Genes ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Hpt Axis

AbstractProgesterone is a natural steroid hormone excreted by animals and humans, which has been frequently detected in the aquatic ecosystems. The effects of the residual progesterone on fish are unclear. In this study, we aimed to examine the effects of progesterone on the hypothalamic-pituitary-thyroid (HPT) axis by detecting the gene transcriptional expression levels. Zebrafish embryos were treated with different concentrations of progesterone from 12 hours post-fertilization (hpf) to 120 hpf. Total mRNA was extracted and the transcriptional profiles of genes involved in HPT axis were examined using qPCR. The genes related to thyroid hormone metabolism and thyroid hormone synthesis were up-regulated in zebrafish exposed to progesterone. These results indicated that progesterone affected the mRNA expression of genes involved in the HPT axis, which might interrupt the endocrine system in zebrafish. Our data also suggested that zebrafish is a useful tool for evaluating the effects of chemicals on the thyroid endocrine system.

scholarly journals Plasma Membrane Transport of Thyroid Hormones and Its Role in Thyroid Hormone Metabolism and Bioavailability

2001 ◽  
Vol 22 (4) ◽  
pp. 451-476 ◽  
Author(s):  
Georg Hennemann ◽  
Roelof Docter ◽  
Edith C. H. Friesema ◽  
Marion de Jong ◽  
Eric P. Krenning ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Membrane Transport ◽  
Hormone Metabolism ◽  
Thyroid Hormone Metabolism

Thyroid hormone metabolism

2018 ◽  
pp. 25-59
Author(s):  
Helen E. Turner ◽  
Richard Eastell ◽  
Ashley Grossman
Keyword(s):  
Thyroid Hormone ◽  
Anterior Pituitary ◽  
Thyroid Stimulating Hormone ◽  
Hormone Resistance ◽  
Hormone Metabolism ◽  
Endocrine Disease ◽  
Autoimmune Hypothyroidism ◽  
Thyroid Hormone Metabolism ◽  
Tsh Secretion ◽  
Hormone Homeostasis

This chapter describes the thyroid gland, its associated hormones, and metabolism. Thyroid function is regulated most importantly by thyroid-stimulating hormone (TSH), also called thyrotropin. In turn, TSH secretion from the anterior pituitary is stimulated by the hypothalamic factor thyrotropin-releasing hormone (commonly abbreviated as TRH). It investigates genetic thyroid disorders, thyroid hormone resistance, autoimmune hypothyroidism, and Graves’ disease. The chapter lists the modalities of thyroid imaging, including ultrasound and radionuclide imaging (RNI), and describes indications of endocrine disease, like goitre, nodules, and malignancy. It describes thyroid hormone homeostasis and conditions affecting homeostasis. It also describes clinical features, causes, and management for disorders including hypothyroidism, hyperthyroidism, thyroiditis, thyroid nodules, and cancer.

Interference of dimethyl α-(dimethoxyphosphinyl) p-chlorobenzyl phosphate (SR-202) in thyroid hormone. metabolism: evidence of inhibition of monodeiodination

1987 ◽  
Vol 112 (1) ◽  
pp. 171-175 ◽  
Author(s):  
C. Liniger ◽  
D. Pometta ◽  
A. G. Burger
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Thyroid Function ◽  
Clinical Investigation ◽  
Compelling Evidence ◽  
Hormone Metabolism ◽  
Thyroid Hormone Metabolism ◽  
Peripheral Conversion

ABSTRACT SR-202 is a non-iodinated potential lipid-altering agent. When administered (100 mg) three times per day for 3 days to six euthyroid subjects it was associated with a 30 ± 3% (mean ± s.e.m.) fall in 3,3′,5-tri-iodothyronine(T3)(P < 0·001), a reciprocal 104 ± 14% rise in 3,3′,5′-tri-iodothyronine (reverse T3, rT3) (P < 0·01), and a 37 ± 7% rise in thyroxine (T4) (P < 0·001). Basal and TRH-stimulated TSH did not change. These results suggested that SR-202 was acting as an inhibitor of the peripheral monodeiodination of T4 to T3. During a second study the same subjects received the same dose of SR-202 for a further 3 days following 15 days of progressive substitutive treatment with l-T4, which they continued to take at 200 μg/day until the end of the study. Despite higher levels of thyroid hormones in the substituted subjects, similar results were observed, serum T3 falling by 40 ± 2% (P < 0·001), serum rT3 and T4 rising by 168 ± 24% (P < 0·01) and 37 ± 9% (P < 0·01) respectively. These changes provide compelling evidence that SR-202 is an inhibitor of the peripheral conversion of T4 to T3 that acts on thyroid hormone metabolism without provoking a counter-regulatory pituitary response. It might prove to be a useful tool for the clinical investigation of thyroid function. J. Endocr. (1987) 112, 171–175

scholarly journals Iodine status among pregnant women after mandatory salt iodisation

2015 ◽  
Vol 115 (3) ◽  
pp. 405-410 ◽  
Author(s):  
İ. Anaforoğlu ◽  
E. Algün ◽  
Ö. İnceçayır ◽  
M. Topbaş ◽  
M. F. Erdoğan
Keyword(s):  
Thyroid Hormone ◽  
Pregnant Women ◽  
Large Scale ◽  
Current Knowledge ◽  
School Age Children ◽  
Thyroid Function Tests ◽  
Hormone Metabolism ◽  
Iodised Salt ◽  
Hormone Synthesis ◽  
Thyroid Hormone Metabolism

AbstractI is essential for thyroid hormone synthesis and neurological development. Various changes occur in thyroid hormone metabolism during pregnancy and I requirements increase significantly. The purpose of this study was to investigate I status among pregnant women in Trabzon, formerly a severely I-deficient area but shown to have become I sufficient following mandatory iodisation of table salt based on monitoring studies among school-age children (SAC) in the area. A total of 864 healthy pregnant women with a median age of 28 (25th–75th percentile 17–47) years participated in the study. None of them were using I-containing supplement. All of them were screened for use of iodised salt, obstetric history, thyroid function tests and urinary I concentrations (UIC), and thyroid ultrasonography was performed. Median UIC was 102 (25th–75th percentile=62–143) μg/l. Median UIC of the patients according to trimesters were 122 µg/l at the 1st, 97 µg/l at the 2nd and 87 µg/l at the 3rd trimester. UIC in the 1st trimester was higher compared with the 2nd and 3rd trimesters (P<0·017). Nodules were present in 17·7 % of women (n 153). The rate of iodised salt usage among pregnant women was 90·7 %. Our study demonstrates that, although the I status among SAC has been rectified, I deficiency (ID) is still prevalent among pregnant women. Current knowledge is in favour of I supplementation in this group. Until the effects of maternal I supplementation in mild ID have been clarified by large-scale prospective controlled trials, pregnant women living in borderline defficient and I-sufficient areas, such as Trabzon city, should receive 100–200 µg/d of I-containing supplements in addition to iodised salt.

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