MECHANISMS IN ENDOCRINOLOGY: The crosstalk between thyroid gland and adipose tissue: signal integration in health and disease

Abstract

Obesity and thyroid diseases are common disorders in the general population and they frequently occur in single individuals. Alongside a chance association, a direct relationship between 'thyroid and obesity' has been hypothesized. Thyroid hormone is an important determinant of energy expenditure and contributes to appetite regulation, while hormones and cytokines from the adipose tissue act on the CNS to inform on the quantity of energy stores. A continuous interaction between the thyroid hormone and regulatory mechanisms localized in adipose tissue and brain is important for human body weight control and maintenance of optimal energy balance. Whether obesity has a pathogenic role in thyroid disease remains largely a matter of investigation. This review highlights the complexity in the identification of thyroid hormone deficiency in obese patients. Regardless of the importance of treating subclinical and overt hypothyroidism, at present there is no evidence to recommend pharmacological correction of the isolated hyperthyrotropinemia often encountered in obese patients. While thyroid hormones are not indicated as anti-obesity drugs, preclinical studies suggest that thyromimetic drugs, by targeting selected receptors, might be useful in the treatment of obesity and dyslipidemia.

Thyrotropin Levels Are Associated with Cardiometabolic Risk Factors in Euthyroid Adolescents

“…As TSH receptors are present on adipocytes, and receptors for leptin have been identified on the TRH-secreting neurons of the paraventricular nucleus (15), evidence points to a bidirectional communication between adipose tissue and the HPT axis that must be overcome to counteract the reductions in energy expenditure typically associated with weight loss. Because decreases in fT3 with weight loss are associated with decreases in resting energy expenditure in both adults and children (43,44), consideration of T3 levels may help to identify further a group of individuals who may require more intensive or prolonged modifications to achieve sustained weight loss.…”

“…Additionally, the HPT axis and serum thyroid hormones are influenced by nutritional status and energy stores, through leptin-mediated crosstalk between adipose tissue and thyrotropin-releasing hormone (TRH) (15). As a consequence, there has been increasing interest in determining if additional serum parameters of thyroid function may better inform assessments of thyroid hormone activity at the tissue level (16).…”

Indices of adiposity and thyroid hormones in euthyroid postmenopausal women

“…According to recent evidence, the HPT axis interacts with adipose tissue to mediate body weight. Thyroid hormones regulate thermogenesis and metabolism by affecting transcription factors that are involved in adipogenesis, genes that regulate lipid metabolism, and genes that regulate thermogenesis (24). In addition, experimental evidence has shown that T 3 is associated with a catabolic effect when it is administered peripherally, resulting in a decrease in body weight.…”

“…In addition, experimental evidence has shown that T 3 is associated with a catabolic effect when it is administered peripherally, resulting in a decrease in body weight. On the other hand, the injection of T 3 into the hypothalamus has been shown to result in anabolic actions, including increased appetite and possibly weight gain, in mammals (24). Finally, fasting has been linked to increased glial deiodinase 2 activity and local production of T 3 , which promotes mechanisms that stimulate orexigenic neurons in mice (24).…”

Zaburzenia funkcji tarczycy u dzieci z otyłością i nadwagą

“…The increased incidence of thyroid cancer is also thought to be related to increasing obesity rates. Possible mechanisms underlying the effect of obesity on thyroid oncogenesis are still being debated [23].…”