Effects of phyto-oestrogens on tissues

Abstract

Recent investigations on the effects of phyto-oestrogens on various tissues have revealed that these diverse molecules may improve human health, particularly by protecting against certain chronic diseases. After a brief examination of the food sources, structures, and general cellular actions of the major phyto-oestrogens, current research ®ndings on cardiovascular disease, skeletal tissues, and reproductive cancers are reviewed. Phytooestrogen concentrations in blood may be maintained at high levels in those consuming soyabean (Glycine max)-based food daily at several meals and exert their effects on target cells through either genomic effects via the classical oestrogen receptors or non-genomic effects mediated by membrane-bound oestrogen receptors or other cellular proteins. The expression of oestrogen receptor (OR) subtypes alpha (a) and beta (b) varies across tissues, and cells that preferentially express OR-b, which may include bone cells, are more likely to respond to phyto-oestrogens. Conversely, reproductive tissues contain relatively more OR-a and may, thus, be differently affected by phyto-oestrogens. Soyabean phytooestrogens appear to prevent the progression of atherosclerosis through multiple interactions, including lowering of plasma lipids and lipoproteins, increased vasodilatation and, possibly, decreased activation of blood platelets and vascular smooth muscle cells. However, a favourable impact on cardiovascular disease morbidity and mortality by a soyabean-enriched western-type diet remains to be shown, and unresolved questions remain regarding dose and form of the phyto-oestrogens in relation to risks and bene®ts. The iso¯avones of soyabean have been shown consistently to have bone-retentive effects in animal studies by several investigators using rodent models, although intakes must be above a relatively high threshold level for a lengthy period of time, and little or no extra bene®t is observed with intakes above this threshold level. The reports of modest or no effects on prevention of bone loss in human and non-human primate studies respectively, may be due to the limited doses tested so far. The relationship between soyabean-food intake and cancer risk has been more extensively investigated than for any other disease, but with less certainty Abbreviations: MNV, N-nitroso-N-methylurea; OR, oestrogen receptor; ORE, oestrogen response element; OVX, ovariectomized; SORM, selective oestrogen receptor modulator.

Immunohistochemical Localization of Estrogen Receptor in the Embryonic Gonad of Male Quail Embryo During Gonadal Differentiation

“…The character of having thick cortex in male quail embryonic gonad after exposure to exogenous estrogens is called "ovotestis" (Perrin et al, 1995;Berg et al, 2001;Oshima et al, 2012). It has been reported that a number of ER in germinal epithelial cells were increased by phytoestrogen (Anderson et al, 1999). This suggests that ER is involved in proliferation of germinal epithelial cells of the embryonic gonads.…”

Apoptotic Bax Gene Expression in Glioblastoma Cells Exposed to Estradiol valerate

“…The investigations on the effects of phyto-oestrogens on various tissues have revealed that these diverse molecules may improve human health, particularly by protecting against certain chronic diseases [8]. It has also been reported that estrogen may have protecting effects against various cancers [9]- [10].…”

Effect of intracerebroventricular infusion of genistein on prolactin and LH secretion in ovariectomized ewes during short days

“…The oestrogenic isoflavones like genistein and biochanin-A may be broken down to the non-oestrogenic 4-ethyl-phenol and organic acids (Anderson et al, 1999). Ruminal microorganisms may take, however, 6 to 10 days to adapt fully to these substrates, so genistein may produce oestrogenic effects in sheep during the first few days after introduction of the phytoestrogenic diet.…”