Endocrine Abstracts

Phytoestrogens bind weakly to oestrogen receptors and can initiate oestrogen-dependent transcription. They are promoted as natural alternatives to HRT and yet epidemiological evidence suggests that they may protect against breast and prostate cancer. Studies in cell-free preparations have shown that phytoestrogens can inhibit the activity of aromatase and that the inhibition is, at least partly, competitive with androgen substrates. The question as to whether chronic exposure ...

Phytoestrogens (PEs) have a weak affinity for the oestrogen receptor. There is, however, no consistent evidence that, on a normal diet, circulating levels of PEs reach sufficient concentrations to exert significant oestrogenic/anti-oestrogenic effects. Phytoestrogens have been implicated in other cellular actions, not all of which necessarily involve the oestrogen receptor. Studies on cell-free systems and cell lines have demonstrated dose-dependent inhibitory effects of PEs o...

Metformin is commonly used to treat insulin resistance in women with polycystic ovary syndrome (PCOS) and also has direct effects on the ovary. The mechanism of this action is unknown, but could be via insulin-independent pathways, namely AMP activated protein kinase (AMPK). AMPK is an energy sensor, activated when ATP levels are depleted causing an inhibition of anabolic and an activation of catabolic pathways. We hypothesised that in the ovary, metformin acts via</...

Extracts of black cohosh (BCE) are frequently used as an alternative to conventional HRT to treat menopausal symptoms, particularly in Germany and the United States. In fact, BCE is the 14th most popular herbal product in the US and in 2003 sales were at least $15.7 million. Evidence for an increased incidence of breast cancer in long-term users of HRT has reduced its use and may increase the use of alternative treatments. These still require rigorous scientific investigation,...

AMH, the fetal testicular sexual differentiative factor, is now implicated in adult ovarian function. Antral follicle immunohistochemistry demonstrated AMH protein and message, the staining peaking around 4 mm. Interestingly, AMH-knockout mice have increased FSH sensitivity. Our aim was to measure AMH in follicular fluid and cell-conditioned medium and AMHRII in normal ovaries from women undergoing TAH/BSO.Follicles were dissected intact, follicular flui...

Recent evidence indicates that the increase in follicle numbers seen in PCOS occurs early in folliculogenesis, and that androgens are implicated in this. In primates and sheep, androgen excess in-utero results in ovarian changes similar to those in PCOS. We have recently shown using a novel in ovo model, that testosterone added to implanted human tissue increased primary follicles compared to untreated tissue (Qureshi et al. 2005). This is similar to the p...

The role of the intra-ovarian insulin-like growth factor (IGF) system in preantral follicle development is unclear. Here we have examined the expression of mRNA for insulin-like growth factor-1 (IGF-1), IGF-2, Type 1-IGF receptor, Type 2-IGF receptor and insulin receptor (IR) in human pre-antral follicles at different stages. Ovarian cortex biopsies (5mm3) were obtained (with informed consent) during gynaecological surgery from six women (age 32.2 plus/minus SD 2.2,...

Background: PCOS is a metabolic disorder associated with long-term health risks including insulin resistance, type 2 diabetes and dyslipidaemia. Metformin improves insulin sensitivity in PCOS and reduces circulating concentrations of markers of endothelial dysfunction, although it is unclear whether this translates into improvements in vascular function.Objective: To determine whether metformin therapy improves arterial stiffness and endothelial function...

Background: Patients with Addison’s disease (AD) and hypopituitarism have increased mortality, mainly from vascular disease. Both diseases are characterised by DHEA(S) deficiency yet this is not usually corrected. It is unclear whether treatment of these conditions with DHEA improves vascular risk.Objective: To evaluate the effects of DHEA on arterial stiffness and endothelial function in subjects with AD and hypopituitarism.M...

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. Although the cause of the anovulation is unknown there are a number of endocrine candidates; hyperinsulinaemia, raised steroid production and increased levels of the sexual differentiative factor anti-Müllerian hormone (AMH). The latter is increasingly thought to be an inhibitor of folliculogenesis. Hyperinsulinaemia in PCOS is now widely treated with metformin and we have shown that thi...