Thyroid hormones short-term effect

The organization of the endocrine system can best be described in relation to the central nervous system. Three levels of endocrine tissues can be distinguished on the basis of their association with the central nervous system (Figure 30-12). The first level consists of those that are (or were) derived from nerve cells these include the hypothalamus, adrenal medulla, thyroid C-cell, and gastrointestinal enterochromaffin cells. The hypothalamus and adrenal medulla still retain their neural connections and can therefore be regarded as endocrine extensions of the nervous system. The C-cell and the gut cells, however, are APUD cells and lack neural connections. These four tissues produce hormonal peptides or amines having, like neurotransmitters, rapid-onset, short-term effects. 

Kirubagaran R, Joy KP (1994) Effects of short-term exposure to methylmercury chloride and its withdrawal on serum levels of thyroid hormones in the catfish Clarias batrachus (L). Bull Environ Contam Toxicol 63 166-170... 

In addition, the metabohsm of OCAs results in the release of large amounts of E into the circulation. As described for KI, I released from OCAs may have effects at the thyroid gland and if used alone to treat hyperthyroidism, OCAs carry the same potential to induce increased secretion of thyroid hormone and exacerbation of thyrotoxicosis. When an OCA is used in the treatment of hyperthyroidism, large doses of antithyroid agents are usually administered concomitantly. However, the combination of OCAs and antithyroid drugs may cause resistance to the antithyroid drugs with time, presumably because of the elevation in intrathyroidal 1 content. Thus, it is recommended that the use of OCAs be reserved for short-term treatment of patients with severe thyrotoxicosis and significant comorbidity (e.g., myocardial infarction, sepsis, stroke) for rapid control of plasma Tj concentrations. 

Zhou T, Ross DG, De Vito MJ, et al. 2001. Effects of short-term in vivo exposure to polybrominated diphenyl ethers on thyroid hormones and hepatic enzyme activities in weaning rats. Toxicol Sci 61 76-82. 

Inadvertent excessive use of thyroid hormones (for example, by eating ground beef contaminated with thyroid hormones (64), the incorrect use of these drugs for the treatment of obesity (65), excessive thyroid substitution therapy, and factitious use of thyroid hormones for psychiatric reasons (66)) result in mild hyperthyroidism, but serious short-term adverse effects are rare. 

PBDEs are estrogen disruptors and neurotoxins. They are believed to cause thyroid and neurodevelopmental effects. Short-term exposure to PBDEs interferes with thyroid function and disrupts hormonal balance. 18 Additive thyrotoxic effects were observed when PBDEs were administered to laboratory animals with PCBs or chlorinated hydrocarbons. 19 PBDE exposure has been linked to neurodevelopmental dysfunctions in children and young adults. 20 21 Administration of PBDE to 10-day-old laboratory animals resulted in impaired spontaneous motor behavior, affected learning and memory, and permanent behavioral effects. 21 ln vitro exposure of PBDE to human breast cancer cells demonstrated estrogenic potencies. 22 ... 

Cyr, D.G. and J.G. Eales. The effects of short-term estradiol treatment on plasma thyroid hormone kinetics in rainbow trout, Salmo gairdneri. J. Fish Biol. 36 391-400, 1990. 

Perhaps the most striking illustration of the pervasive developmental effects of thyroid hormones is provided by children with severe thyroid hormone deficiency from early childhood, a condition termed cretinism. This may either be endemic in regions of severe iodine deficiency or sporadic due to failure of the thyroid to develop normally or defects in the synthesis of thyroid hormone. Affected children are dwarfed with short extremities, have mental retardation, and are inactive and listless. Other manifestations include facial puffiness, enlarged tongue, dry and doughy skin, slow heart rate, and decreased body temperature. Eor full recovery, treatment of patients with cretinism must be initiated before these florid features are apparent. Thus, pregnant women in areas of endemic cretinism due to iodine deficiency are supplemented with iodine and aU newborns are screened for thyroid hormone deficiency in many developed nations. 

The Effect of Short-Term Soy Consumption on Thyroid Hormone Leveis... 

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