Thyroid hormones factors affecting

Protirelin (thyrotrophin-releasing hormone. TRH. thyrotrophin-releasing hormone factor. TRF) is a tripeptide agent that modulates the release of thyrotrophin (and prolactin) from the pituitary and thence, in turn, thyroid hormone that affects metabolism and a number of other processes in the body. Therapeutically, protirelin is used to assess thyroid disorders and function in patients who suffer from hypopituitarism or hyperthyroidism. 

The secretion of anterior pituitary hormones is controlled in part by hypothalamic regulatory factors that are stored in the hypothalamus and are released into the adenohypophyseal portal vasculature. Hypothalamic regulatory factors so far identified are peptides with the exception of dopamine. Secretion of anterior pituitary hormones is also controlled by factors produced more distally that circulate in the blood. Predominant control of hormone production may be relatively simple, as with thyroid-stimulating hormone (TSH), the production of which is primarily stimulated by thyrotropin-releasing hormone (TRH) and inhibited by thyroid hormones, or it may be complex, as with prolactin, the production of which is affected by many neurotransmitters and hormones. 

There is no discrete target tissue for thyroid hormones virtually every cell in the body is affected by thyroid hormones in some way. These hormones are intimately involved in the maintenance of normal function in virtually every cell type, including cellular responsiveness to other hormones, to the availability of metabolic substrates, to growth factors, and so on. Thyroid dysfunction can produce dramatic changes in the metabolism of proteins, carbohydrates, and lipids at the cellular level that can have repercussions for the operation of the cardiovascular, gastrointestinal, musculoskeletal, reproductive, and nervous systems. Some of the clinical manifestations of thyroid dysfunction are presented next in the discussions of hypothyroid and hyperthyroid states. 

Drug interactions The thioamides do not directly interact with other drugs. Because the thioamides can affect thyroid hormone synthesis and therefore decrease clotting factor turnover, the thioamides may increase anticoagulant activity. 

Retinoids are classed as morphogens, small molecnles released from one type of cells that can affect the growth and differentiation of neighboring cells. Their normal roles in the hnman body are to indnce differentiation of some cells, stop the differentiation of others, and both snppress and indnce apoptosis in different cell types. Their diverse actions come from the diversity of their receptors. The two classes of retinoid receptors are retinoid X receptors (RXRs) and retinoic acid receptors (RARs), each with a, P, and y snbclasses. RXRs are versatile they bind to RARs and to other nnclear receptors such as thyroid hormone receptors. Once activated, the receptors act as transcription factors that in turn regulate the expression of genes that control ceUnlar growth and differentiation. ... 

H5. Hamolsky, M. W., Stein, M., Fischer, D. B., and Freedberg, A. 8., Further studies of factors affecting the plasma protein-thyroid hormone complex. Endocrinology 68, 662-670 (1961). 

Interestingly, the control group had a significant decrease in T4 levels at 90 days (p<0.01), as compared to the other time intervals, though the change was still not as great as seen in treated animals. However, several factors are known to affect thyroid hormone levels in rat plasma including environmental temperature the strain, age, and sex of the rat and the time of day (Thomas and Thomas 1994). 

Thus, some endogenous small molecular compounds that are able to mimic the biological effect of the natural neurotrophic factors, or to stimulate their synthesis and secretion, might be promising candidates for pharmaceutical agents of various neurodegenerative diseases. Sex hormones, thyroid hormones, vitamin D and their derivatives are already known to affect survival and differentiation of dissociated mouse embryo brain in cultures or in cultured rat septal neurons. However, application of these hormones to patients with normal hormone function... 

Other Factors Affecting the Thyroid-Stimulating Hormone (TSH)... 

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