The majority of breast cancers are oestrogen dependent and in postmenopausal women the supply of oestrogens in breast tissue is derived from the peripheral conversion of circulating androgens. There is, however, a paradox concerning the epidemiology of breast cancer and the dietary intake of phytoestrogens that bind weakly to oestrogen receptors and initiate oestrogen-dependent transcription. I...

The bioavailability in human subjects of non-nutrient plant factors, including dietary flavonoids and phyto-oestrogens, is of great importance relative to their reported health protective effects. These effects include protection against heart disease, and also in the case of the phyto-oestrogens, hormone-dependent cancers. Epidemiological studies have shown flavonoid intake (mostly quercetin) ...

Tamoxifen is a potent inhibitor of specific oestrogen-induced yolk protein synthesis by chicken liver. The oestradiol receptor in salt extracts of liver nuclei from oestrogen-treated chicks has a K(d) for oestradiol of 0.7+/-0.2nm. Tamoxifen and its metabolite, monohydroxytamoxifen, compete for binding to the salt-soluble nuclear receptor with K(i) values of 2.6 and 0.1nm respectively. The anti...

Timing is everything when trying to land a mate. In many species, female receptivity tomale sexual advances is synchronized to fertility and is mediated by steroid hormones produced in the gonads, such as oestrogens. How these hormones tune neural circuits to transition females to mate-seeking mode is unclear. In a series of elegant experiments, neuroscientist Jenna McHenry and colleagues in Ga...

The story of the isolation and characterization of the oestrogenic hormones begins in i923, when Allen and Doisy first used the vaginal smear method to test the activity of substances isolated from the ovary. The smear is spread on a microscopic slide and stained with a suitable dye and the type of cells observed shows at which stage of the sexual cycle an animal is. At the ' resting ' stage on...

There is presently considerable interest in endocrine disruption which is a new area of endocrinology concerned with chemicals that mimic hormones, in particular sex steroids. It has been hypothesised that exposure to such chemicals may be responsible for adverse effects in both humans and wildlife. Until now, chemicals that mimic oestrogens (so-called xenoestrogens) have been the main focus of...