Role of T4 in the Modulation of Pituitary T3 Nuclear Receptors (T3nR) in Hypothyroid Rats
It is now well documented that cellular responses to thyroid hormones are mediated by a nuclear receptor, the concentration of which is known to vary with tissue, as well as with physiopathological conditions (see 1 for review). Regarding possible changes in T3nR with variations of thyroid function, there is still controversy which may be due to the fact that such variations would be tissue dependent. Indeed, no changes in the concentration of T3nR have been reported in the liver, kidney, and heart of hypothyroid animals (2–4), whereas more recently an increase in the liver and the brain (5–7), and a reduction in the lung, liver, and the pituitary gland (8–11) have been shown in hypothyroid rats. In pituitary tumor cells and in the rat pituitary gland, T3 has been found to induce a decrease in the concentration of nuclear receptors (12,13).
KeywordsPituitary Gland Nuclear Receptor Pituitary Tumor Cell Iopanoic Acid Physiopathological Condition
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