Thyroid Hormone Secretion Research Articles

Thyroid diseases: Pathophysiology and new hopes in treatment with medicinal plants and natural antioxidants

The thyroid gland regulates a wide range of physiological activities such as growth, metabolism, homeostasis, and cell proliferation and differentiation through the secretion of thyroid hormones (THs). Thyroid diseases are among the most common endocrine disorders, hypothyroidism is the most common clinical thyroid dysfunction. Hyperthyroidism means increased thyroid function and refers to excess metabolic state due to excessive synthesis and secretion of TH. Medicinal plants have been identified and used by humans throughout history. To name the herbs and natural antioxidants used to treat thyroid disorders including hypothyroidism and hyperthyroidism. Related articles were obtained using the Google Scholar, PubMed, and ScienceDirect databases. The results of this study indicate that medicinal plants include Fucus vesiculosus, Aegle marmelos, Coleus forskohlii, Linum usitatissimum, Withania somnifera, Commiphora mukul, Nigella sativa, and Bacopa monnieri. They can improve the hyperthyroidism in improving hyperthyroidism and herbal remedies, Melissa officinalis A. marmelos, Lycopus europaeus, Leonurus cardiaca, and Aloe barbadensis be effective. Herbal drugs cause comparatively fewer side effects. It is believed that the drugs derived from the plants are very safe and produce significant effects in the treatment of various diseases. Today, traditional medicine is being widely used and plants are still considered a major source of natural antioxidants that can serve as a clue for the development of new drugs.

Onemocnění štítné žlázy v seniorském věku

The incidence of most thyroid diseases are prevalent in women in ratio 8 : 1 to men, and especially hypothyroidism arises with age. Unrecognized thyroid dysfunction leads to increased: cardiovascular risk, bone fractures, cognitive impairment, depression, and mortality. The symptoms of thyroid diseases can be nonspecific or common in seniors with ageing complaints. The interpretation of thyroid function tests, the physiological changes in secretion and metabolism of thyrotropin (TSH) and thyroid hormones must be considered, as well as the influence of comorbidities, certain drugs, and individual set point of pituitary gland. According to many observations the serum TSH, thyroxine (T4), concentrations depend on age, comorbidities, and medical treatment - these together sometimes make the diagnosis of thyroid dysfunction complicated in older population. The observational data may suggest a diminished pituitary sensitivity to T4 in the ageing population. According to several studies, serum TSH concentration is probably age-dependant and the upper limit of TSH could be 5.28-5.9 mIU/l in those who are > 70 years old. Therapy of thyroid dysfunction is different in elderly persons than in young people; hypothyroidism should be treated with caution, because high doses of thyroxine can lead to cardiac arrhythmias and increased bone turnover. Hyperthyroidism could be treated either with surgery or preferable with radioiodin. Especially the diagnosis of subclinical hypothyroidism should be made with caution after concerning different important circumstances. Nevertheless there are certain conditions, when subclinical hypothyroidism must be treated. Key words: ageing - hyperthyroidism - hypothyroidism - thyroid diseases.

Effects of environmental heat stress on reproduction and its management in chickens

The effects of environmental heat stress on reproduction in chickens were reviewed to find out the associated physiological changes and the interplay of the physiological events, after which the role of certain measures in the management of heat stress were identified. The normal rectal temperature for chicken is 40.6 - 43.0 oC with 45 oC as the upper limit of safety. The rectal temperature begins to increase when the ambient temperature increases, but this is prevented by panting to increase heat loss by respiratory evaporation of water. Chickens are said to be heat stressed when their body heat builds up during high ambient temperature. The physiological responses associated with it include respiratory alkalosis from panting, reduced feed intake and efficiency, reduced absorption of calcium, decrease in secretion of thyroid hormones, estrogen, progesterone and testosterone, and increased secretion of glucocorticoids, luteinising hormone and follicle stimulating hormone. Consequently, heat stress produces decrease in anabolism, increase in catabolism and insulin resistance, loss in body weight, delayed sexual maturity, reduction in number and quality of eggs, infertility in male and female chickens and reduced hatchability of fertile eggs with the greatest effect being on the number and quality of eggs produced. The impact of environmental heat stress remains a challenge as it affects reproduction in chickens and researches in this area are necessary to support increased productivity of chickens in hot semi-arid regions.Keywords: Chickens, eggs, heat stress, management, reproduction

Receptor for advanced glycation end products reveals a mechanism regulating thyroid hormone secretion through the SIRT1/Nrf2 pathway.

Advanced glycation end products (AGEs) play a causative role in the complications involved with diabetes mellitus (DM). Nowadays, DM with hypothyroidism (DM-hypothyroidism) is indicative of an ascended tendency in the combined morbidity. In this study, we examine the role of the receptor (RAGE) played for AGEs in thyroid hormone (TH) secretion via the silent information regulator 1 (SIRT1)/nuclear factor erythroid-derived factor 2-related factor 2 (Nrf2) pathway. Blood samples were collected from patients with type 2 DM (T2DM)-hypothyroidism and from patients with T2DM, followed by detection of serum AGEs level. The underlying regulatory mechanisms of RAGE were analyzed in association with the treatment of high glucose, siRNA against RAGE, AGE, SIRT1, or Nrf2 vector in normal immortalized thyroid Nthy-ori 3-1 cells. Serum of patients with T2DM-hypothyroidism indicated promoted levels of AGEs vs those with just T2DM. Both AGEs and high glucose triggered cellular damage, increased oxidative stress, as well as displayed a decreased survival rate along with TH secretion in the Nthy-ori 3-1 cells. Moreover, AGEs and high glucose also led to RAGE upregulation, both SIRT1 and NRF2 downregulation, and the decreased expression of TH secretion-related proteins in Nthy-ori 3-1 cells. Notably, these alternations induced by the AGEs can be reserved by silencing RAGE or upregulating either SIRT1 or Nrf2, indicating a mechanism of regulating TH secretion through the SIRT1/Nrf2 pathway. Collectively, our data proposed that AGEs and high glucose exerted a potent effect on cellular damage and TH deficiency in Nthy-ori 3-1 cells through the RAGE upregulation as well as SIRT1/Nrf2 pathway inactivation. This mechanism may underlie the occurrence of DM-hypothyroidism.

Differentiated thyroid cancer: Why does it affect predominantly women during the reproductive period and have higher incidence of mutual association with breast cancer?

Differentiated thyroid cancer (DTC) is markedly more common in women than men, and its occurrence and risk for poorer prognosis are associated with pregnancy. Further, it is known that there is a high frequency of co-occurrence of DTC and breast cancer. Although the underlying mechanisms that contribute to these phenomena are not entirely clear, 2 hypotheses are proposed here. First, human chorionic gonadotropin (hCG) produced by the placenta may be involved, since hCG has a similar function to stimulate the thyroid as thyroid-stimulating hormone (TSH), the latter of which is known to play a role in causing DTC and may promote breast cancer through the secretion of thyroid hormones (THs). Second, thyrotropin-releasing hormone (TRH), which is stimulated by suckling in the puerperal period, induces the secretion of not only TSH and thus indirectly THs, but also prolactin (PRL), which can accelerate the development of breast cancer. These hypotheses also explain the pregnancy-associated transient increase in breast cancer risk, while inhibition of estrogen by PRL may have a long-term preventive effect on breast cancer. Pregnancy-associated hyperthyroidism may also account for female preponderance of thyroid disease in general as well as tumors in organs that the thyroid hormone targets such as cardiac myxoma and diffuse-type gastric carcinoma.

Diagnosis and Comprehensive Management of Thyroid Storm in Pregnancy: A Case Report

Thyroid crisis is an emergency in Endocrinology which is characterized by acute hypermetabolic with rapid deterioration which is one of non-obstetric maternal death cause. This condition is rare serious complication, affect about 1-2% of patients with hyperthyroidism. Unrecognized and untreated thyroid storm causing life threatening condition. Management of thyroid storm in pregnancy is aimed to reduce the synthesis and secretion of thyroid hormone and pregnancy management. Explain about optimal diagnostic and treatment strategies of pregnancy with thyroid storm. A 28 years woman admitted to Obstetrics Emergency Room, third pregnancy with 36 weeks 2 weeks gestation was complained of shortness of breath since 3 days ago. History of hyperthyroid since 1 year ago, often palpitate, sweating and tremor. History of consumption PTU 3x100 mg oral but lack of obey. History of hypertension since 27 weeks gestation. Physical examination found that blood pressure was 170/110 mmHg, pulse rate 130 bpm, respiratory rate bpm, 84% oxygen saturation, 38.5°C temperature. Diffuse tiroid gland was palpable with size 1 x 2 cm, ronkhi in whole lung field. Obstetric examination was found breech presentation with FHB: 131 bpm. Laboratory result were TSHs / FT4: 0.24 / 1.72, T4 Total: 104. Thyroid storm diagnostic based on Burch Wartofsky score: 55. Initial treatment performed with oxygen administration, loop diuretics, chest X-ray examination and echocardiography. Followed by PTU therapy, lugolization and corticosteroids. After 48 hours of stabilization, we performed cesarean section and postoperative care at Intensive Care Unit. Thyroid storm is rare pregnancy complication. Diagnostic criteria using Burch and Wartofsky score. Management of thyroid storm in pregnancy includes anti thyroid drugs, lugol solution, corticosteroids and pregnancy management. Diuretic therapy is given due to fluid overload, besides that screening of thyroid hormone profile is important during antenatal care.

Calcified ectopic TSH-secreting pituitary adenoma mimicking craniopharyngioma: a rare case report and literature review

Among pituitary adenomas, which are relatively common brain tumors, elements of ectopic, thyroid-stimulating hormone (TSH) secretion, and intratumoral calcification are unusual. Here, we present an extremely rare case of a calcified ectopic TSH-secreting pituitary adenoma arising from the pars tuberalis mimicking craniopharyngioma based on neuroimaging findings. To our knowledge, this is the first case report of calcified ectopic TSH-secreting pituitary adenoma without symptoms of excessive thyroid hormone secretion.

Thyroid Function Disruptors: from nature to chemicals.

The modern concept of thyroid disruptors includes man-made chemicals and bioactive compounds from food that interfere with any aspect of the hypothalamus-pituitary-thyroid axis, thyroid hormone biosynthesis and secretion, blood and transmembrane transport, metabolism and local action of thyroid hormones. This review highlights relevant disruptors that effect populations through their diet: directly from food itself (fish oil and polyunsaturated fatty acids, pepper, coffee, cinnamon and resveratrol/grapes), through vegetable cultivation (pesticides) and from containers for food storage and cooking (bisphenol A, phthalates and polybrominated diphenyl ethers). Due to the vital role of thyroid hormones during every stage of life, we review effects from the gestational period through to adulthood, including evidence from in vitro studies, rodent models, human trials and epidemiological studies.

Hubungan Kadar TSH Terhadap Kadar FT4 Pada Pasien Tiroid Di Bangkalan

AbstractThyroid disorder disease ranks second most in the list of metabolic diseases after diabetes mellitus (DM). Thyroid disease or Thyroid abnormalities is a condition of abnormalities in a person due to the disorder of the thyroid gland. TSH is a primary factor that controls thyroid cell growth and synthesis also thyroid hormone secretion. TSH secretion is stimulated by low levels of T3 and T4 and by the hormone TRH (Thyroid Releasing Hormone) the hypothalamus is inhibited by elevated levels of T3 and T4. T3 and T4 are circulating in the plasma, most of which are bound with proteins, Thyroid Binding Globulin (TBG) and a small part in free form that are Free Triiodotironine (FT3) and Free Thyroxine (FT4). The free hormone (FT3 and FT4) is an actively metabolic fraction which is known to be quantitative. Currently the measurement of free hormone levels should be part of a complete examination of the status of the thyroid gland. The purpose analyzes the levels of TSH, FT4 and proves the relationship between the two in patients with thyroid disorders. This examination by using ELISA method is with EIA competitive principles and sandwiches. The samples are serum of patients with thyroid disorders at RSUD Bangkalan and Farmalab Laboratory from October to November 2017.The 30 samples obtaines an average result of TSH level of 1.9 mIU / L and an average FT4 level of 2.8 ng / dl. Next test Kolmogorov-Smirnov and Spearrman's test results obtained if the variable one value rose (high) then the other variable down (low). It can be concluded that there is an opposite relationship between TSH levels and FT4 levels, if TSH levels increase, the FT4 level decreases, and so it is also in contrast Keywords: TSH, FT4, thyroid disorders

Regulatory effects of immune system thyroid stimulating hormone β-subunit splice variant (TSHβv) on thyroid hormone secretion in mice.

Abstract It has been known for over three decades that thyroid stimulating hormone (TSH) is made by cells of the immune system, yet little is known about the biological significance of that. Studies in my laboratory identified a novel splice variant of the TSH β-subunit (TSHβv) that is produced by bone marrow (BM) hematopoietic cells and peripheral leukocytes in humans and mice. As shown here, recombinant mouse TSHβ (rTSHβ) binds in a dose-dependent manner to the TSH receptor (TSHR) on the mouse AM macrophage cell line, and circulating T4 levels are suppressed 38% in mice 24 hrs after injection of rTSHβv. Moreover, TSHβ-producing leukocytes traffic to the thyroid during systemic L. monocytogenes infection. TSHβv is suppressed in mouse macrophages following transfection with short-hairpin RNA TSHβv (shRNA-TSHβv) expression plasmids, and is suppressed in BM cells transduced with shRNA-TSHβv lentivirus pseudoparticles. These findings collectively suggest that binding of immune system TSHβv to the TSHR on thyroid follicular cells may serve to modulate thyroid hormone output, thus providing a novel mechanism for regulating host metabolism during times of immune stress. Experiments are underway in mice to understand the in vivo involvement of immune system TSHβv in healthy conditions, and during chronic inflammation such as in autoimmune thyroiditis.

Liver Dysfunction in Hypothyroid Non-Pregnant Women

Objective: To evaluate the effects of under secretion of thyroid hormones and its relation with liver markers i.e. alanine transaminase (ALT) and aspartate transaminase (AST) in non-pregnant women.
 Methods: This cross-sectional study was conducted in Khyber Teaching Hospital Peshawar from March 2014 to March 2015. The study was performed on 150 non-pregnant women in the age group of 18-70, attending the outpatients departments of Khyber Teaching Hospital for thyroid screening. The exclusion criteria were pregnancy, hypertension, renal impairment and known history of liver ab- normalities. Thyroid and liver function tests were performed for all the patients and control using standard kits and procedure. Normal subjects in the same age group were selected randomly from the local population of Peshawar city and were used as control (N) for the study. Competitive ELISA tech- nique was used for the analysis of T3 and T4 on Dia 710 microplate reader, while sandwich ELISA was used for TSH analysis. Quantitative tests for both ALT and AST were performed according to the international federation of clinical chemist (IFCC) protocols on Erbamannhein chemistry auto-analyser (Germany) using standard Erba kits.
 Results: ALT and AST level was found to be lower in the patient groups [Overtly hypothyroid (Oh): 24.35 ± 1.11 IU/L, sub-clinically hypothyroid (Sh): 16.85 ± 0.55 IU/L] than the control group (N: 29.69 ±3.28 IU/L). A significant positive correlation was observed between AST and TSH (thyroid-stimulating hormone) in the control group (N) (p=0.002) and negative correlation in overtly hypothyroid (Oh) and sub-clinically hypothyroid (Sh) groups, respectively. No other significant correlation was observed be- tween ALT, TSH, T3 (triiodothyronine) and T4 (thyroxine) in any other groups.
 Conclusion: Both liver enzymes (ALT and AST) were found to be lower in the patients groups (Oh and Sh) as compared to control group (N).

TSH Has Effects on Peripheral Thyroid Hormone Metabolism That Are Mild but Run Counter to Its Direct Effects on Thyroid Hormone Secretion

Clinical ThyroidologyVol. 30, No. 3 SummariesTSH Has Effects on Peripheral Thyroid Hormone Metabolism That Are Mild but Run Counter to Its Direct Effects on Thyroid Hormone SecretionCharles H. EmersonCharles H. EmersonSearch for more papers by this authorPublished Online:1 Mar 2018https://doi.org/10.1089/ct.2018;30.138-141AboutSectionsView articleView Full TextPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View articleFiguresReferencesRelatedDetails Volume 30Issue 3Mar 2018 InformationCopyright 2018 American Thyroid Association, Inc.To cite this article:Charles H. Emerson.TSH Has Effects on Peripheral Thyroid Hormone Metabolism That Are Mild but Run Counter to Its Direct Effects on Thyroid Hormone Secretion.Clinical Thyroidology.Mar 2018.138-141.http://doi.org/10.1089/ct.2018;30.138-141Published in Volume: 30 Issue 3: March 1, 2018PDF download

MANAGEMENT OF ENDOCRINE DISEASE: Pitfalls on the replacement therapy for primary and central hypothyroidism in adults.

Hypothyroidism is one of the most common hormone deficiencies in adults. Most of the cases, particularly those of overt hypothyroidism, are easily diagnosed and managed, with excellent outcomes if treated adequately. However, minor alterations of thyroid function determine nonspecific manifestations. Primary hypothyroidism due to chronic autoimmune thyroiditis is largely the most common cause of thyroid hormone deficiency. Central hypothyroidism is a rare and heterogeneous disorder characterized by decreased thyroid hormone secretion by an otherwise normal thyroid gland, due to lack of TSH. The standard treatment of primary and central hypothyroidism is hormone replacement therapy with levothyroxine sodium (LT4). Treatment guidelines of hypothyroidism recommend monotherapy with LT4 due to its efficacy, long-term experience, favorable side effect profile, ease of administration, good intestinal absorption, long serum half-life and low cost. Despite being easily treatable with a daily dose of LT4, many patients remain hypothyroid due to malabsorption syndromes, autoimmune gastritis, pancreatic and liver disorders, drug interactions, polymorphisms in DIO2 (iodothyronine deiodinase 2), high fiber diet, and more frequently, non-compliance to LT4 therapy. Compliance to levothyroxine treatment in hypothyroidism is compromised by daily and fasting schedule. Many adult patients remain hypothyroid due to all the above mentioned and many attempts to improve levothyroxine therapy compliance and absorption have been made.

Effects of repeated potassium iodide administration on genes involved in synthesis and secretion of thyroid hormone in adult male rat.

A single dose of potassium iodide (KI) is recommended to reduce the risk of thyroid cancer during nuclear accidents. However in case of prolonged radioiodine exposure, more than one dose of KI may be necessary. This work aims to evaluate the potential toxic effect of repeated administration of KI. Adult Wistar rats received an optimal dose of KI 1 mg/kg over a period of 1, 4 or 8 days. hormonal status (TSH, FT4) of treated rats was unaffected. Contrariwise, a sequential Wolff-Chaikoff effect was observed, resulting in a prompt decrease of NIS and MCT8 mRNA expression (-58% and-26% respectively), followed by a delayed decrease of TPO mRNA expression (-33%) in conjunction with a stimulation of PDS mRNA expression (+62%). we show for the first time that repeated administration of KI at 1 mg/kg/24h doesn't cause modification of thyroid hormones level, but leads to a reversible modification of the expression of genes involved in the synthesis and secretion of thyroid hormones.

Thyroid stimulating hormone stimulates the expression of glucose transporter 2 via its receptor in pancreatic \u03b2 cell line, INS-1 cells

Thyroid stimulating hormone (TSH) stimulates the secretion of thyroid hormones by binding the TSH receptor (TSHR). TSHR is well-known to be expressed in thyroid tissue, excepting it, TSHR has also been expressed in many other tissues. In this study, we have examined the expression of TSHR in rat pancreatic islets and evaluated the role of TSH in regulating pancreas-specific gene expression. TSHR was confirmed to be expressed in rodent pancreatic islets and its cell line, INS-1 cells. TSH directly affected the glucose uptake in INS cells by up-regulating the expression of GLUT2, and furthermore this process was blocked by SB203580, the specific inhibitor of the p38 MAPK signaling pathway. Similarly, TSH stimulated GLUT2 promoter activity, while both a dominant-negative p38MAPK α isoform (p38MAPK α-DN) and the specific inhibitor for p38MAPK α abolished the stimulatory effect of TSH on GLUT2 promoter activity. Finally, INS-1 cells treated with TSH showed increased protein level of glucokinase and enhanced glucose-stimulated insulin secretion. Together, these results confirm that TSHR is expressed in INS-1 cells and rat pancreatic islets, and suggest that activation of the p38MAPK α might be required for TSH-induced GLUT2 gene transcription in pancreatic β cells.

Effect of antioxidants supplementation on plasma hormonal profiles in Hallikar cattle during different seasons

Present study was carried out to ascertain the influence of different seasons on hormonal profiles in Hallikar cattle. Two groups (control and supplemented) of healthy female Hallikar cattle with six animals in each group selected from Madabal Village of Ramanagara District, Karnataka, India, were utilized for the present study. Selected animals were exposed to environmental stressors during three different seasons (winter, summer and rainy) by allowing them for grazing daily. Animals of control group received no supplementation but supplemented group received oral supplementation of vitamin E and selenium, during the study period. Blood samples collected from all the animals at monthly interval during three different seasons were processed to obtain the plasma which were stored at - 80 ºC until they are utilized for determination of hormones like triiodothyronine (T3), thyroxine (T4), insulin and cortisol using radioimmunoassay technique. In the present study, triiodothyronine and thyroxine levels reduced significantly (P less than 0.05) during summer season compared to other seasons in control group animals. In both control and supplemented group, plasma insulin levels declined significantly (P less than 0.05) and plasma cortisol levels increased significantly (P less than 0.05) during summer compared to other seasons. Form the study, it was concluded that the summer stress reduces the thyroid and pancreatic activity leading reduced secretion of thyroid hormones and insulin. Further, the summer stress stimulates the adrenal cortical activity leading to enhanced secretion of the cortisol in Hallikar cattle

Effects of peripheral ghrelin on growth performance, selected blood biochemical parameters and thyroid hormone in Japanese quail (Coturnix coturnix japonica)

The aim of present study was to investigate the effects of peripheral administration of ghrelin on performance and some serum parameters of Japanese quail. One hundred twenty 21 day-old male Japanese quails were divided into three groups for a 35 days experimental rearing period. The control group (G0) included no injection as an intact, the second group (treatment 1/G50) received 50 ng ghrelin/kg body weight (BW), and the third group (treatment 2/G100) was given 100 ng ghrelin/kg BW. Ghrelin was administrated (I. P. administration) at the onset of the experimental rearing period on 21-day old birds. Blood samples were taken at two different times: 1) 12 hrs after the injection, and; 2) at the end of the rearing period (on day 35). The effects of ghrelin were evaluated during experimental rearing periods. There were no changes in feed intake and body weight gain (BWG) following ghrelin administration at different dosages (50 or 100 ng/ kg BW), whereas a minor decrease in feed intake was observed in G100 group. Feed conversion ratio (FCR) is significantly decreased in G50 and G100, compared to control (P<0.05). Thyroxin (T4) was increased in ghrelin-administered groups in both samples (short/long-term). In conclusion, ghrelin administration in Japanese quails may improve FCR, and stimulate secretion of thyroid hormones, without severe effects on feed intake. However, it did not have considerable effects on carcass characteristics and serum biochemical measures in short and long-terms in Japanese quails

Antithyroidic and hepatoprotective properties of high-resolution liquid chromatography–Mass spectroscopy-standardized Piper betle leaf extract in rats and analysis of its main bioactive constituents

Background: Hyperthyroidism can be a serious health problem, if not treated properly. This investigation primarily aimed to evaluate the thyroid regulatory and hepatoprotective activities of ethyl acetate fraction (EPBL) of Piper betle leaf extract in L-thyroxine (L-T4)-induced hyperthyroid rats. Materials and Methods: Effects of EPBL extract at a prestandardized dose of 50 mg/kg (p. o.) were studied in L-T4 (500 μg/kg/d, i. p.)-administered rats to examine the alterations in the levels of serum triiodothyronine (T3), thyroxine (T4), thyrotropin, alanine transaminase, and aspartate aminotransferase; in the activities of hepatic 5'-monodeiodinase (5'DI), glucose-6-phosphatase (G-6-Pase), and Na+-K+-ATPase; in the level of tissue malondialdehyde (MDA) and lipid hydroperoxides (LOOHs); and in the activities of antioxidants. Results: Administration of the EPBL extract reversed the T4-induced increase in serum thyroid hormones, the liver marker enzymes, MDA, and LOOH but enhanced the activities of antioxidative enzymes and reduced the glutathione content. Light microscopic findings of liver histology revealed distorted hepatic tissue architecture in hyperthyroid animals that were improved by the EPBL administration. High-resolution liquid chromatography–mass spectroscopy analysis revealed four main flavonoid glycosides such as quercetin, rutin, kaempferol, and luteolin. Conclusion: For the first time, our findings revealed the antithyroidic property of EPBL in T4-induced hyperthyroidism, without any hepatotoxicity. The antithyroidic and antioxidative properties of EPBL in hyperthyroid animals could be due to the presence of flavonoid glycosides in the extract which might have inhibited the thyroid hormone secretion and conversion of T4 to T3 through an inhibition of 5'DI. Abbreviations used: EPBL: Ethyl acetate Piper betel; HR-LC-MS: High-resolution liquid chromatography–mass spectroscopy; T3: Triiodothyronine; T4:Thyroxine; TSH: Thyrotropin; PTU: Propylthiouracil; ALT: Alanine transaminase; AST: Aspartate aminotransferase; DTT: Dithiothreitol; G-6-Pase: Glucose-6-phosphatase; Na+-K+-ATPase: Sodium-potassium adenosine triphosphatase; 5'DI: 5'-monodeiodinase; MDA: Malondialdehyde; LOOHs: Lipid hydroperoxides; SOD: Superoxide dismutase; CAT: Catalase; GSH: Reduced glutathione; GPx: Glutathione peroxidase; CPCSEA: Committee for the Purpose of Control and Supervision of Experiments on Animals.

Effects of substances on plants' active compounds on changes in the hormone levels of the pituitary–Thyroid axis in hyperthyroidism and hypothyroidism

The roles of thyroid glands in different functions of the body have been well explained such that hypothyroidism and hyperthyroidism can impair the metabolism and normal functions of the body's tissues. Recently, using medicinal plants and their active compounds in treating diseases has attracted attention, and the people's tendency to use these compounds, which are considered to be low risk and to cause no side effect, is increasing. Because changes in the levels of thyroid hormones have considerable effects on body physiology and play a substantial role in the pathogenesis of different diseases, it is necessary to conduct further studies on hyperthyroidism and hypothyroidism and also the effects of plants and their compounds on thyroid hormone secretion rates. This review was conducted to present the information on thyroid hormones, as metabolism-regulating agents, and their association with different diseases as well as the effects of plant-based active compounds on changes in the hormone levels of the pituitary–thyroid axis in hyperthyroidism and hypothyroidism. Results indicated that disrupted serum levels of the thyroid hormones lead to increased incidence of cardiovascular disease, diabetes, depression, menstrual disorders, and kidney disease. The most important effective compounds on these hormones include flavonoids, coumarins, alkaloids, minerals, essential oil components, such as terpinene, gamma-terpinene, and limonene, and antioxidant compounds that directly influence thyroid and change serum levels of the thyroid hormones through inhibiting thyroid peroxidase. Other mechanisms of change in thyroid hormone levels by plant-based compounds are related to decrease in lipoxygenase activity and increase in the activities of catalase and dismutase. It can therefore be argued that using medicinal plants and their compounds can be a novel and efficient approach to develop drugs for thyroid diseases.

Effects of fluoride exposure on thyroid hormone level and intelligence in rats

Objective: To investigate the effects of fluoride exposure on the thyroid hormone level and intelligence in rats and to investigate the biomarkers of intellectual impairment induced by high fluoride exposure. Methods: A total of 24 clean healthy Sprague-Dawley rats were randomly divided into control group (tap water containing 0.344 mg/L fluoride) and low-, medium-, and high-fluoride exposure groups (tap waters containing 10, 50, and 100 mg/L sodium fluoride, respectively). One male rat was cohabited with two female rats in the same group. After the offspring rats were weaned, 12 offspring rats (male/female ratio=1∶1) with a similar body weight in each group were subjected to the same treatment for the parental offspring. The offspring rats were sacrificed on the 60th day after birth. The weight of offspring rats was measured. Serum thyrotropin (TSH) , free triiodothyronine (FT(3)) , and free thyroxine (FT(4)) levels were measured by enzyme-linked immunosorbent assay. The learning and memory abilities of the rats were evaluated by Morris water maze test. The expression of mitochondrial fission 1 (Fis1) and mitofusin 1 (Mfn1) in blood was measured by Western blot. Results: The offspring rats in the medium-and high-fluoride exposure groups had significantly lower serum TSH and FT(4) levels than those in the control group (P<0.05). The place navigation test showed that the offspring rats in the medium-and high-fluoride exposure groups had significantly longer escape latency than those in the control group (P<0.05) , and the high-fluoride exposure group had a significantly longer escape distance than those in the control group (P<0.05). The spatial probe test showed that the offspring rats in the low-, medium-, and high-fluoride exposure groups had significantly shorter swimming time and distance in the target quadrant and total swimming time and distance than those in the control group (P<0.05). Compared with the offspring rats in the control group, those in the low-, medium-, and high-fluoride exposure groups had significantly higher expression of Fis1 (P<0.05) , and those in the low- and medium-fluoride exposure groups had significantly higher expression of Mfn1 (P<0.05) . Conclusion: High fluoride exposure can reduce the secretion of thyroid hormone and the abnormality of mitochondrial dynamics in peripheral lymphocytes may provide a clue to identifying the biomarkers of intellectual impairment induced by fluoride exposure.