Estrogen physiological actions

Steroid hormones (e.g., cortisol and estrogen) are hydro-phobic and insoluble in water. These hormones circulate in plasma, reversibly bound to transport proteins (e.g., cortisol-binding globulin and sex-hormone binding globulin) with only a small fraction free or unbound available to exert physiological action.The half-life of steroid hormones is 30 to 90 minutes. Free steroid hormones, being hydrophobic, enter the cell by passive diffusion and bind with intracellular receptors either in the cytoplasm or the nucleus. ... 

Estrogens induce progesterone receptors, which allows for a greater physiologic action of progesterone. 

As described in an earlier section, estrogen induces its physiological action by binding with specific receptors in the plasma membrane and eventually triggering multiple gene activations to carry out cell proliferation and differentiation. It is now established that estrogen receptors themselves cannot carry out the transcription alone, but need an... 

All steroid hormones (estrogen, progestins, glucocorticosteroids and aldosterone) are now believed to exert their specific physiological action in a three step sequence binding to a specific cytosol receptor, transfer from cytosol to a specific nuclear receptor associated with chromatin, and modulation of gene expression in the target cell [184]. 

Although the positive effects of ERT have been well established, it has been shown that the cell proliferative actions of estrogen can increase the incidence of breast cancer in some patients. In addition, duration of exposure to physiological levels of unopposed estrogens is an established risk factor for breast, uterine, and ovarian cancer. In an effort to attain pharmaceutical agents that oppose the carcinogenic... 

As an example of suspected endocrine disruptors (EDs), studies of the estrogenic action of bisphenol A (BPA) have been in progress in medical, physiological, and biological fields. In this situation, physicochemical approaches are required to get the structural information of BPA trapped in biomembranes. Most recently, we have determined the site and the orientation of BPA trapped in phospholipid vesicles by NMR, using the HCS rule [47]. In particular, we have succeeded in monitoring the NMR spectral changes of phospholipid vesicles, which are induced by the BPA delivery. 

Levin ER. Cell localization, physiology, and nonge-nomic actions of estrogen receptors. J Appl Physiol. 2001 91 1860-1867. 

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