scholarly journals The influence of certain medicinal products on the function of the hypothalamo-pituitary-thyroid axis and the efficiency of substitution therapy with thyroid hormones

2010 ◽  
Vol 56 (3) ◽  
pp. 52-56
Author(s):  
E A Troshina ◽  
N V Mazurina ◽  
M Iu Iukina ◽  
N A Ogneva
Keyword(s):  
Thyroid Hormones ◽  
Medicinal Products ◽  
Substitution Therapy ◽  
Medicinal Preparations ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Thyroidal Status ◽  
Somatic Diseases

The influence of various medicinal preparations on the function of the hypothalamo-pituitary-thyroid axis is discussed. Thyroidal status at different somatic diseases is considered alongside the efficiency of substitution therapy with thyroid hormones for the management of hypothyroidism.

scholarly journals The pituitary-thyroid axis in healthy men living under subarctic climatological conditions

2001 ◽  
Vol 169 (1) ◽  
pp. 195-203 ◽  
Author(s):  
J Hassi ◽  
K Sikkila ◽  
A Ruokonen ◽  
J Leppaluoto
Keyword(s):  
Thyroid Hormones ◽  
Climatic Factors ◽  
Feedback Mechanism ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Healthy Men ◽  
Non Invasive ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Serum Tsh

In order to evaluate the effects of climatic factors on the secretion of thyroid hormones and TSH in a high latitude population, we have taken serum and urine samples from 20 healthy men from northern Finland (67 degrees -68 degrees N) every 2 months for a period of 14 months. Serum free triiodothyronine (T(3)) levels were lower in February than in August (3.9 vs 4.4 pmol/l, P<0.05) and TSH levels were higher in December than during other months (2.1 vs 1.5-1.7 mU/l, P<0.01). Serum total and free thyroxine (T(4)), total T(3) and reverse T(3) levels and urinary T(4) levels were unchanged. Urinary T(3) levels were significantly higher in winter than in summer. Serum free T(3) correlated highly significantly with the outdoor temperature integrated backwards weekly for 7-56 days (r=0.26 for 1-56 days) from the day when the blood samples were taken. Serum TSH did not show any significant correlation with the thyroid hormones or with the integrated temperature of the previous days, but it did show an inverse and significant correlation (r=-0.31) with the ambient luminosity integrated backwards for 7 days from the day when the blood sample was taken. The gradually increasing correlation between outdoor temperatures and serum free T(3) suggests that the disposal of thyroid hormones is accelerated in winter, leading to low serum free T(3) levels and a high urinary free T(3) excretion. Since there was no correlation between thyroid hormones and serum TSH, the feedback mechanism between TSH and thyroid hormones may not be the only contributing factor, and other factors such as ambient luminosity may at least partly determine serum TSH in these conditions. Also urinary free T(3) appears to be a novel and non-invasive indicator for thyroid physiology.

Homocysteine, pituitary and thyroid hormones in children with different physical development levels after forest fires in the Chornobyl exclusion zone

2021 ◽  
pp. 11-18
Author(s):  
Yu.I. Bandazhevskyi ◽  
◽  
N. F. Dubova ◽  
Keyword(s):  
Thyroid Hormones ◽  
Forest Fires ◽  
Physical Development ◽  
Blood Levels ◽  
Exclusion Zone ◽  
Peripheral Tissues ◽  
Before And After ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Development Levels

Objective We performed a comparative assessment of the blood levels of homocysteine, pituitary and thyroid hormones in children with different levels of physical development before and after forest fires in the Chornobyl exclusion zone (ChEZ) in 2015. Methods: We used immunochemical, instrumental, mathematical and statistical methods. Results: The analysis of variable dynamics was performed in 336 adolescents of the Polisskyi and the Ivankivskyi districts of Kyiv region. An association was found between homocysteine (Нсу), hormones of the pituitary-thyroid axis and physical development of children. A statistically significantly higher level of Нсу was observed in the adolescents from the Ivankivskyi district in comparison with the children from the Polisskyi district. Forest fires in the spring and summer of 2015 in the ChEZ should be considered the main cause for the increase in Нсу in the blood of the adolescents. The increased level of Т3 in the peripheral tissues induced by Нсy and TSH contributed to a decrease in the physical development index values. Due to a decrease in the intensity of the Т4 deiodination process, the insufficient formation of Т3 in the peripheral tissues was recorded in the group of children with a disharmonious high physical development.

scholarly journals Circulating leptin and thyroid dysfunction

2003 ◽  
Vol 149 (4) ◽  
pp. 257-271 ◽  
Author(s):  
T Zimmermann-Belsing ◽  
G Brabant ◽  
JJ Holst ◽  
U Feldt-Rasmussen
Keyword(s):  
Thyroid Hormones ◽  
Uncoupling Proteins ◽  
Severe Illness ◽  
Research Activity ◽  
Mitochondrial Uncoupling ◽  
Adaptive Thermogenesis ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
The Subject ◽  
Underlying Mechanisms

The identification and sequencing of the ob gene and its product, leptin, in 1994 opened new insights in the study of the mechanisms controlling body weight and led to a surge of research activity. Since its discovery, leptin has been the subject of an enormous amount of work especially within the fields of nutrition, metabolism and endocrinology. Leptin is accepted as an adipose signal, and even though the underlying mechanisms are not fully clarified, leptin, in addition to the thyroid hormones, is believed to be involved in regulation during the switch from the fed to the starved state. It is not clear whether leptin and the melanocortin pathways interact with the thyroid axis under physiological conditions other than during starvation or in response to severe illness, both states in which the hypothalamo-pituitary-thyroid axis may be severely suppressed. In addition to the suggested central relationship between leptin and thyroid hormones, there might also be a peripheral relationship although this effect is not clear. Both thyroid hormones and leptin might be involved in the adaptive thermogenesis through mitochondrial uncoupling proteins and heat production because both thyroxine and triiodothyronine are involved in the starvation-induced decrease in thermogenesis. Both rodent and human studies of leptin have failed to show any consistent relationship between thyroid function and serum leptin concentrations. However, leptin might have an important role in thyroid pathophysiology due to thyroid hormone involvement in thermogenesis and regulation of uncoupling proteins. In this review, we have focused on leptin in relation to thyroid pathophysiology.

Postnatal development of brain TRH, serum TSH and thyroid hormones in the male and female rat

1986 ◽  
Vol 112 (1) ◽  
pp. 7-11 ◽  
Author(s):  
L. Gayo ◽  
B. Bonet ◽  
A. S. Herranz ◽  
R. Iglesias ◽  
M.J. Toro ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Thyroid Hormones ◽  
Postnatal Development ◽  
Female Rat ◽  
Male And Female ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
The Central Nervous System ◽  
Serum Tsh

Abstract. The postnatal development of immunoreactive TRH in the central nervous system (CNS), serum TSH and thyroid hormones was studied in both male and female normal rats. While in most structures of the CNS, TRH increased until day 20–30, serum TSH values peaked at day 15 as did T4. Significant differences were also obtained between both sexes in these parameters. These data further support the fact that pituitary-thyroid axis maturation is independent of brain TRH.

scholarly journals Effect of repetitive potassium iodide on elderly rat’s thyroid

2019 ◽  
Vol 14 ◽  
pp. 05007
Author(s):  
Dalila Lebsir ◽  
Elsa Cantabella ◽  
Teni Ebrahimian ◽  
Dimitri Kereselidze ◽  
Stephane Grison ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Single Dose ◽  
Thyroid Hormones ◽  
Mrna Expression ◽  
Clinical Biochemistry ◽  
The Elderly ◽  
The Other ◽  
Male Rats ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis

Background: Nuclear power plant emergencies had often been accompanied by radioactivity release into the environment, thyroid cancer is one of the major health consequences due to the effect of radioactive iodine (131I) that emits ϒ ray and β particles resulting in thyroid DNA damage and late onset thyroid cancer. Intake of a single dose of potassium iodide (KI) is recommended to reduce this risk. However in case of prolonged radioiodine release as noticed during Chernobyl and Fukushima accidents, more than one dose of KI may be basic to ensure adequate protection [1]. Whereas a single dose of KI is admitted to be safe, knowledge about the effects of repeated KI administration are scarce, few studies demonstrated the potential efficiency of repetitive KI intake in humans [2] and non-human primates [3] without hormonal variations. These studies are relevant in the field of radiation protection and give a base evidence of the possible use of repetitive KI. On the other hand, we have studies on rodents that showed an impact of chronic iodine excess on pituitary thyroid axis function [4]. Our previous work on adult male rats demonstrated the safety of repeated administration of KI over 8 days [5]. Indeed in the elderly persons KI administration in case of nuclear emergency remains a topic of debate, because of the possible impact in cardiovascular diseases. Thyroid hormones are well-known for their profound effects on cardiovascular function and metabolism; myocardial and vascular endothelial tissues have receptors for thyroid hormones and are sensitive even to subtle changes in the concentrations of circulating pituitary and/or thyroid hormones i.e. subclinical hypothyroidism and hyperthyroidism. It is well established that hyperthyroidism induces a hyper-dynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Atrial fibrillation is the most common cardiac arrhythmia in the elderly, the prevalence and incidence increase with advancing age [6]. Several interventional trials showed that treatment of subclinical thyroid diseases improves cardiovascular risk factors, which implies potential benefits for reducing cardiovascular events. Objective: The aim of this study is to assess the effects of repeated KI intake on the thyroid function of aged male rats. Methods: A twelve months old male rats were subjected to either KI or saline solution over 8 days. Clinical biochemistry, pituitary and thyroid hormones level, and thyroid genes expression were analyzed 30 days after the treatment discontinuation. Findings: urinary assessment shows a subtle increase of some parameters (Creatinin, Uric Acid, Urea, Glucose, Potassium, Sodium and Chlorine), plasma biochemistry reveals a subtle variation of some parameters (an increase of Creatinin, Glucose and phosphorus; and a decrease of Chlorine level). Regarding pituitary-thyroid hormones we get a significant decrease of TSH level without thyroid hormones variation. At the molecular level, we observe a significant increase of TPO (+100%), AIT (+299%) and Tg (+38%) mRNA expression. On the other hand we get a significant decrease of TSHR (-51%) mRNA expression. Conclusion and perspectives: Our first results indicate that repeated KI intake affects the clinical biochemistry and the pituitary-thyroid axis function in elderly rats. To go further we are investigating the impact of these variations on the cardiovascular function and its parameters. Cardiac output data, cardiovascular gene expression, oxidative stress and inflammatory analysis are being processed. This study will contribute to the evolution of iodine policy and the harmonization of the current KI guidelines.

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