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Natural compounds with potential antioxidant properties have been used in the form of food supplements or extracts with the intent to prevent or treat various diseases. Many of these compounds can activate the cytoprotective Nrf2 pathway. Besides, some of them are known to impact the thyroid gland, often with potential side-effects, but in other instances, with potential utility in the treatment of thyroid disorders. In view of recent data regarding the multiple roles of Nrf2 in the thyroid, this review summarizes the current bibliography on natural compounds that can have an effect on thyroid gland physiology and pathophysiology, and it discusses the potential implication of the Nrf2 system in the respective mechanisms. Literature searches for articles from 1950 to 2018 were performed in PubMed and Google Scholar using relevant keywords about phytochemicals, Nrf2 and thyroid. Natural substances were categorized into phenolic compounds, sulfur-containing compounds, quinones, terpenoids, or under the general category of plant extracts. For individual compounds in each category, respective data were summarized, as derived from in vitro (cell lines), preclinical (animal models) and clinical studies. The main emerging themes were as follows: phenolic compounds often showed potential to affect the production of thyroid hormones; sulfur-containing compounds impacted the pathogenesis of goiter and the proliferation of thyroid cancer cells; while quinones and terpenoids modified Nrf2 signaling in thyroid cell lines. Natural compounds that modify the activity of the Nrf2 pathway should be evaluated carefully, not only for their potential to be used as therapeutic agents for thyroid disorders, but also for their thyroidal safety when used for the prevention and treatment of non-thyroidal diseases.

Context: Abnormal maternal thyroid function in pregnancy may impair fetal brain development, but more evidence is needed to refine and corroborate the hypothesis.Objective: To estimate the association between maternal thyroid function in early pregnancy and neuropsychological performance of the child at 5 years of age.Design: Follow-up study.Participants: A cohort of 1153 women and their children sampled from the Danish National Birth Cohort. Maternal thyroid-stimulating hormone (TSH) and free thyroxine (fT4) were measured in stored biobank sera from early pregnancy.Main outcomes measures: Child neuropsychological test results (Wechsler Intelligence Scale/Test of Everyday Attention), test of motor function (Movement Assessment Battery), and results of parent and teacher reports (Behavior Rating Inventory of Executive Function/Strengths and Difficulties Questionnaire).Results: Altogether 145 children (12.6%) were born to mothers with abnormal thyroid function in the early pregnancy. High maternal TSH and low fT4 were associated with lower child verbal intelligence quotient (adjusted mean difference TSH ≥ 10 mIU/L vs 0.1 to 2.49 mIU/L, -8.9 [95% confidence interval (CI), -15 to -2.4]; fT4 < 10 pmol/l vs 12.0 to 18.99 pmol/l, -13 [95% CI, -19 to -7.3]). Abnormal maternal thyroid function was also associated with adverse motor function and teacher-reported problems of executive function and behavior, and these associations were dominated by exposure to maternal hypothyroxinemia.Conclusions: Maternal thyroid hormone abnormalities were associated with adverse neuropsychological function of the child at 5 years of age. For intelligence, marked hypothyroidism was important, whereas for motor function and executive and behavior problems, maternal hypothyroxinemia was predominant.

OBJECTIVE: Both subclinical hypothyroidism and the metabolic syndrome have been associated with increased risk of coronary heart disease events. It is unknown whether the prevalence and incidence of metabolic syndrome is higher as TSH levels increase, or in individuals with subclinical hypothyroidism. We sought to determine the association between thyroid function and the prevalence and incidence of the metabolic syndrome in a cohort of older adults. DESIGN: Data were analysed from the Health, Ageing and Body Composition Study, a prospective cohort of 3075 community-dwelling US adults. PARTICIPANTS: Two thousand one hundred and nineteen participants with measured TSH and data on metabolic syndrome components were included in the analysis. MEASUREMENTS: TSH was measured by immunoassay. Metabolic syndrome was defined per revised ATP III criteria. RESULTS: At baseline, 684 participants met criteria for metabolic syndrome. At 6-year follow-up, incident metabolic syndrome developed in 239 individuals. In fully adjusted models, each unit increase in TSH was associated with a 3% increase in the odds of prevalent metabolic syndrome (OR, 1.03; 95% CI, 1.01-1.06; P = 0.02), and the association was stronger for TSH within the normal range (OR, 1.16; 95% CI, 1.03-1.30; P = 0.02). Subclinical hypothyroidism with a TSH > 10 mIU/l was significantly associated with increased odds of prevalent metabolic syndrome (OR, 2.3; 95% CI, 1.0-5.0; P = 0.04); the odds of incident MetS was similar (OR 2.2), but the confidence interval was wide (0.6-7.5). CONCLUSIONS: Higher TSH levels and subclinical hypothyroidism with a TSH > 10 mIU/l are associated with increased odds of prevalent but not incident metabolic syndrome.

The regulation of adipose tissue mass and energy expenditure is currently subject to intensive research, which primarily relates to the discovery of leptin. Leptin is a peptide, which is the product of the obese (ob) gene expressed in adipose tissue of several species icluding humans. Leptin is supposed to serve both as an index of fat mass and as a sensor of energy balance. Administration of recombinant murine leptin in ob/ob-mice, which do not produce leptin, decreases food intake and increases thermogenesis both of which result in a reduction in body weight and adipose tissue mass. The calorigenic effect of leptin presumably acts through an increase in sympathetic outflow which in turn activates the beta3 adrenergic receptor in brown adipose tissue. The regulation and action of endogenous leptin in humans are less well understood, and clinical grade recombinant human leptin is so far not available. Serum leptin correlates logarithmically with total body fat in both normal weight and obese subjects, which suggest insensitivity to leptin in obese patients. Furthermore, more rapid excursions in serum leptin have been reported following short-term changes in caloric intake and administration of insulin. Growth hormone (GH) exerts pronounced effects on lipid metabolism and resting energy expenditure. The lipolytic actions of GH appear to involve both increased sensitivity to the beta-adrenergic pathway, and a suppression of adipose tissue lipoprotein lipase activity. The calorigenic effects of GH have been shown not only to be secondary to changes in lean body mass. Growth hormone administration furthermore increases the peripheral conversion of thyroxine to triiodothyronine, which may contribute to the overall actions of GH on fuel and energy metabolism. So far, little is known about the effects of GH and iodothyronines on serum leptin levels in humans. We therefore measured serum leptin levels and energy expenditure before and after the administration of GH and triiodothyronine, alone and in combinaion, in a randomized double-blind placebo-controlled study in healthy young male adults. The dose of triiodothyronine was selected to obtain serum levels comparable to those seen after GH administration.

Molecular biology has had a major impact on our concepts of the immune system and its relation to neuroendocrine axes, in particular, the adrenal, gonadal, and thyroid axes. It is now well established that not only are the biosynthetic and catabolic pathways of glucocorticoids and sex hormones (estrogen, progesterone, and testosterone) closely related but that the receptors for these hormones are part of a supergene family of receptors which include (in addition to these hormone receptors) the mineralocorticoid receptor, thyroid hormone receptor, retinoic acid receptors, and vitamin D receptors. This suggests a complex network of steroid hormones and receptors for the control and integration of a multitude of physiologic functions at a systemic level. The immune system seems to be tightly integrated into this homeostatic neuroendocrine regulatory network. The neurophysiologic and biochemical events that promote successful adaptation during stressful situations are now identified for illnesses that seem to occur as a result of or are associated with dysregulation of the stress response. One difficulty in interpreting the mechanisms of HPA axis dysfunction in autoimmune-inflammatory syndromes arises from the plasticity of the hormonal systems involved. Levels of hormones produced and receptors reset rapidly with changes in the hormonal milieu (deficiency or excess) and have likely changed during the course of the chronic immune disorder. This, in turn, is further confounded by the pleomorphic natural history of most autoimmune-inflammatory diseases such as SS. The levels of sex hormones and their receptors are tightly linked to HPA axis function. It may be that significant changes in the estrogen-to-androgen ratio or the ratio of their receptors alter the activity of steroid-sensitive cells such as the individual immune cells or epithelial cells, thus providing a means for endocrine regulation of the immune response in SS. Studies in the closely related disorder RA support this hypothesis. Taken together, adrenal and gonadal steroid hormone deficiency plus elevated PRL levels probably greatly facilitate cellular immunity in SS patients. This hypothesis in SS is supported by a growing body of data indicating that RA develops as a consequence of a deficiency in adrenal and gonadal steroid hormone production. It is noteworthy that the findings in female SS patients indicated a central deficiency in all three neuroendocrine axes: adrenal, gonadal, and thyroid. At present, it is not clear if any one system plays a primary role in the expression of the disease. Rather, it is likely that the net effect involves the synergistic and antagonistic effects of multiple hormones, making the specific effects of individual hormones difficult to discern. Rheum Dis Clin North Am

Most children born small for gestational age (SGA) normalize their size through spontaneous catch-up growth within the first 2 yr after birth. Some SGA children fail to do so and maintain an abnormally short stature throughout childhood. We have previously reported that high dose GH treatment (66 or 100 microg/kg x day s.c. over 2 yr; age at start, 2-8 yr; n = 38) induces pronounced catch-up growth in short children born SGA, thereby normalizing their height and weight in childhood. Here, we report on the further prepubertal growth course of these children over the first 4 yr after withdrawal of early, high dose GH treatment. Of the 38 treated children, none developed precocious puberty, and 22 remained prepubertal. Mean age of the latter at start of GH was 4.4 yr, height was -3.7 SD score, and height after adjustment for midparental height was -2.9 SD score. Height increased by an average of 2.5 SD during the 2 yr of GH treatment and decreased by 0.4 and 0.3 SD, respectively, during the first and second year after GH withdrawal. Subsequently, when stature was not extremely short at the start (mean adjusted height SD score, -2.7; n = 13), no further GH treatment was given, and the adjusted height was stabilized around -1.0 SD score; when stature was very short at the start (mean adjusted height, -3.3 SD score; n = 9), a second course of GH treatment (66 microg/kg x day s.c.) was initiated either 2 yr (n = 5) or 3 yr (n = 4) after initial GH withdrawal. This second course was associated with renewed catch-up growth and also resulted in a mean adjusted height of -1.0 SD score. In each subgroup, the pattern of the weight course paralleled that of the height course; GH treatment was well tolerated. In conclusion, early, discontinuous, high dose GH treatment appears to be a safe and efficient option to normalize prepubertal height and weight in the majority of short SGA children. It remains to be examined whether the normalized stature will be maintained during pubertal development, either with or without further GH treatment.

Upon reaction with electrons, oxygen is transformed into reactive oxygen species (ROS). It has long been known that ROS can destroy bacteria and destroy human cells, but research in recent decades has highlighted new roles for ROS in health and disease. Indeed, while prolonged exposure to high ROS concentrations may lead to non-specific damage to proteins, lipids, and nucleic acids, low to intermediate ROS concentrations exert their effects rather through regulation of cell signalling cascades. Biological specificity is achieved through the amount, duration, and localisation of ROS production. ROS have crucial roles in normal physiological processes, such as through redox regulation of protein phosphorylation, ion channels, and transcription factors. ROS are also required for biosynthetic processes, including thyroid hormone production and crosslinking of extracellular matrix. There are multiple sources of ROS, including NADPH oxidase enzymes; similarly, there are a large number of ROS-degrading systems. ROS-related disease can be either due to a lack of ROS (e.g., chronic granulomatous disease, certain autoimmune disorders) or a surplus of ROS (e.g., cardiovascular and neurodegenerative diseases). For diseases caused by a surplus of ROS, antioxidant supplementation has proven largely ineffective in clinical studies, most probably because their action is too late, too little, and too non-specific. Specific inhibition of ROS-producing enzymes is an approach more promising of clinical efficacy.

Using male rats of Wistar strain, studies were made on the influences of the thyroid and thymic systems upon the changes of weight and histochemical findings of the prostatic gland, testicle, seminal vesicle and adrenal gland. Simultaneously, effects of sexual hormones which added to the thyroid and thymic agents were also observed. The results are summarized as follows. 1) Observ a tions of short duration (3 and 5 weeks) in the thyroid groups revealed a slight increase in weight of the prostatic gland, a decrease in ACP and an increase in ALP following thyroidectomy or administration of MTU, and a decrease in weight of the prostatic gland and increases in ACP and RNA with administration of thyroid powder. The results indicated that supression of thyroid function yields an increase in weight and hypofunction of the prostatic gland while hyperthyroidism makes a decrease in weight and hyperfunction of the prostatic gland. 2) Obse r vations of long duration (3 and 5 months) in the thyroid groups showed an increase in weight and decrease in function of the prostatic gland following administration of MTU, while a decrease in weight and increases in Zn and SD of the prostatic gland after administration of thyroid powder. However when the grade of suppression or acceleration of the thyroid function is exceeded, both of weight and function of the proststic gland were decreased. 3) Administration of sexual hormones in association with experimental thyroid disfunctions resulted intenser effects of the sexual hormones upon the prostatic gland. 4) In thyroid groups, weight of the testicle shoWed a slight increas e after thyroidectomy and administration of MTU or thyroid powder. The level of SD in seminal vesicle the yielded decreases after thyroidectomy or administration of MTU and an increase after administration of thyroid powder. Furthermore, with thyroidectomy or with administration of MTU, increases in weight, amount of Sudan III stainable substance and 17 KS of the adrenal gland were demonstrated during short observations period, while decreases in these values were shown during long observation period. With administration of thyroid powder, despite a slight decrease in weight of the adrenal gland, Sudan 'III stainable substance and 17 KS revealed increases in short observation period and decreases in long observation period, making a diphasic pattern. 5) Following thymectomy, the prostatic gland showed an increase in weight and hyperfunction with increases of Zn and SD. Administration of thymic agent resulted decreases in weight and function of the prostatic gland with decreases of RNA, Zn and SD. 6) Administration of male or female sexual hormones in association with thy m ectomy or treatment with thymic agent demonstrated a more intense effects of sexual hormones upon gonads in the cases of thymectomy with sexual hormonal administration than the cases of simultaneous treatment with thymic agent and sexual hormones. 7) Weight of the testicle increased after thymectomy a n d decreased with administration of thymic agent. The level of SD in the seminal vesicle coincided with that of in the prostatic gland. Thymectomy also resulted a decrease in weight and an increase of stainability of the adrenal gland, while results of vice versa were obtained with administration of thymic agent.

Using male rats of Wistar strain, studies were made on the influences of the thyroid and thymic systems upon the changes of weight and histochemical findings of the prostatic gland, testicle, seminal vesicle and adrenal gland. Simultaneously, effects of sexual hormones which added to the thyroid and thymic agents were also observed. The results are summarized as follows. 1) Observ a tions of short duration (3 and 5 weeks) in the thyroid groups revealed a slight increase in weight of the prostatic gland, a decrease in ACP and an increase in ALP following thyroidectomy or administration of MTU, and a decrease in weight of the prostatic gland and increases in ACP and RNA with administration of thyroid powder. The results indicated that supression of thyroid function yields an increase in weight and hypofunction of the prostatic gland while hyperthyroidism makes a decrease in weight and hyperfunction of the prostatic gland. 2) Obse r vations of long duration (3 and 5 months) in the thyroid groups showed an increase in weight and decrease in function of the prostatic gland following administration of MTU, while a decrease in weight and increases in Zn and SD of the prostatic gland after administration of thyroid powder. However when the grade of suppression or acceleration of the thyroid function is exceeded, both of weight and function of the proststic gland were decreased. 3) Administration of sexual hormones in association with experimental thyroid disfunctions resulted intenser effects of the sexual hormones upon the prostatic gland. 4) In thyroid groups, weight of the testicle shoWed a slight increas e after thyroidectomy and administration of MTU or thyroid powder. The level of SD in seminal vesicle the yielded decreases after thyroidectomy or administration of MTU and an increase after administration of thyroid powder. Furthermore, with thyroidectomy or with administration of MTU, increases in weight, amount of Sudan III stainable substance and 17 KS of the adrena