Estrogen physiologic effects

Steroid hormones are divided into six classes, based on physiological effects estrogens, androgens, progestins, glucocorticoids, mineralocorticoids and vitamin D 847... 

ER-Luc Estrogenic compounds activation Estrogen receptor molecular, indicative of chronic physiological effects 17 3-estradiol, xenoestrogens 6.8 ng EEQ/kg, 5 - 15%, Natural estrogenic compounds nd... 

Male and female hormones are produced primarily in the gonads. Androgens are synthesized in the testes in the male. In the female, the ovaries are the principal sites of estrogen and progestin production. As discussed in Chapter 29, small amounts of sex-related hormones are also produced in the adrenal cortex in both sexes, which accounts for the fact that small amounts of hormones of the opposite sex are seen in females and males that is, low testosterone levels are seen in females, and males produce small quantities of estrogen. However, under normal conditions, the amounts of sex-related hormones produced by the adrenal cortex are usually too small to produce significant physiologic effects. 

The multiple drug effects on smooth muscles are also little understood. Thus, isoprenaline relaxes and adrenaline and noradrenaline contract the isolated rat aorta, but all three catecholamines increase cyclic AMP formation [61]. Adrenaline induces relaxation and prostaglandin Ei contraction in the estrogen-treated rat isolated myometrium, but both adrenaline and prostaglandin Ei elevate the cyclic AMP level in the tissue [62]. An example of a critical evaluation of the evidence linking cyclic AMP to a physiological effect (cardiac contractility) is that of Sobel and Mayer [63]. 

Since only small amounts of hormone are necessary to induce dramatic cellular and physiological effects, an organism should be sensitive to any alteration in the amount of hormone or a blockage of the estrogen or other receptor. Toxicants that are endocrine disrupters work in two basic ways (Figure 5.19). In the first instance, the toxicant mimics the hormone, producing a change in... 

Tarrant, A. (2002) Estrogen action in scleractinian corals sources, metabolism and physiological effects. PhD Dissertation, University of Hawaii, 186 pp. 

To conclude on the question of physiological effects, some apparent benefits of certain natural phenols were mentioned in Chapter 1. However, recently a number of synthetic phenols have been implicated as environmentally persistent and weakly to markedly estrogenic in their action. In consequence it has been suggested that they may be the etiological agents in several human disorders (ref. 331). The relative biodegradability (ref. 285) which appears in certain cases to favour natural compared with synthetic phenolic compounds may be a useful environmental factor. 

Natural conjugated estrogens are derived from equine urine. The proportions and concentrations of the various estrogens are unpredictable. The synthetic conjugated products are derived from plants (e.g., soy, yams) and contain a more clearly defined population of estrogens in proportions that are also more clearly defined. The two preparations appear equipotent with regard to physiologic effects. 

In addition to their structural similarities, adrenocorticoids, estrogens, progestins, and androgens share a common mode of action. They are present in the body only in extremely low concentrations (e g., 0.1-1.0 nM), they exert potent physiologic effects on sensitive tissues, and they bind with high affinity to intracellular receptors. Extensive research activities directed at elucidation of the general mechanism of steroid hormone action have been performed for several decades, and many reviews have appeared (2,3,4,5,6,7). 

Setchell KDR. Non-steroidal estrogens of dietary origin possible roles in health and disease, metabolism and physiological effects. Proc. Nutr. Soc. NZ 20, 1-21, 1995. 

Physiological effects and regulatory mechanisms of endogenous estrogens... 

---