Thyroid hormone regulation brain

Thyroid hormones regulate processes of terminal brain differentiation, such as dendritic and axonal growth, synaptogen-esis, neuronal migration and myefination. They also modulate... 

The alterations in morphological organization of the brain resulting from hypothyroidism have been documented [10-13]. Numerous biochemical parameters are affected by altered thyroid states (for review see 14-16). Recent biochemical data on the effect of thyroid hormones on nerve cell differentiation indicate that they regulate microtubule assembly by changing the concentration and/or the activity of MAPS (tau fraction) [17]. The critical period of effectiveness of thyroid hormones in brain maturation raises a special problem. The correct organization of... 

DEVELOPMENTAL AND THYROID HORMONE REGULATION OF Na,K-ATPase ISOFORMS IN THE BRAIN... 

Thyroid hormone regulates a significant portion of the increase in Na,K-ATPase activity during development (6). However, in the adult brain Na,K-ATPase synthesis is not... 

Schmitt, C.A. and A.A. McDonough. Developmental and thyroid hormone regulation of two molecular forms of Na,K-ATPase in brain. J. Biol. Chem. 61 10439-10444, 1986. 

Schematic representation of the major steps in the regulation of thyroid hormone secretions and metabolism at five levels, namely, brain, hypothalamus, pituitary thyrotropes, thyroid, and peripheral tissues.

For example, alternative transcription-control elements regulate expression of the mammalian gene that encodes transthyretin (TTR), which transports thyroid hormone in blood and the cerebrospinal fluid that surrounds the brain... 

The thyroid gland is the only part of the body that absorbs iodine. Thyroid cells use iodine to produce thyroid hormones, which regulate metabolism. Low levels of iodine in the diet can lead to thyroid-hormone deficiencies and goiters, which are enlarged thyroid glands. In serious cases, low levels of thyroid hormones can cause birth defects and brain damage. In the United States, potassium iodide is added to most table salt to protect against dietary iodine deficiency. Even small amounts of added iodine can prevent iodine-deficiency disorders. However, there are parts of the world in which iodine deficiency is still prevalent. 

Recent studies of the regulation of thyroid hormone metabolism in the brain of the rat indicate that the intracellular brain T3 level is dependent on the serum T4 and not on serum T3, as is the case with the liver, heart and lungs (Larsen, 1989 Oppenheimer and Schwartz, 1997). 

Altogether, these findings indicate not only that a transfer of maternal thyroid hormone, namely of T4, to the fetus is effective from early pregnancy, but also that the systems regulating the availability of T3 to the fetal brain are expressed and likely operating by that time. 

The thyroid hormones, T4 and T3, play numerous, profound roles in regulating metabolism, growth, and development and in maintaining homeostasis. Their reactions and products influence carbohydrate metabolism, protein synthesis and breakdown, and cardiovascular, renal, and brain function. It generally is believed that these actions result from effects of thyroid hormones on protein synthesis. 

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