Non-reproductive Actions of Sex Steroids

In addition to their classical sex-related roles, sex-steroids have important effects on the nervous system and immune function. In discussing recent results of steroid research, this monograph pays special attention to the effects of hormone replacement therapy in menopausal women.

---

Sex steroids have a number of physiological effects in addition to their classical sex-related roles. This book brings together clinicians and basic researchers from a number of disciplines to discuss the non-reproductive actions of sex steroids. In many instances, sex steroids mediate the expression of a variety of genes by influencing the activity of intracellular receptors, which in turn bind to hormone response elements in the promoters of hormone-regulated genes. Direct membrane-mediated effects have also been described. Sex steroids have numerous effects on the brain, and although many of these are directed to neural functions underlying reproduction, others are more broadly related to brain function. Among these are effects on cognitive function, motor coordination (high levels of oestrogen exacerbate symptoms of Parkinson's disease), depressive illness and dementia (oestrogen has been shown to improve cognitive function in Alzheimer's disease patients). Neurosteroids also have an important role in nerve repair. The protective role of oestrogen against cardiovascular disease in women is widely documented: the mechanism behind this cardioprotective effect is discussed.
The incidence of autoimmune disease is higher in women than in men, and oestradiol appears to exacerbate the symptoms of many of these diseases, with the exception of rheumatoid arthritis, where oestrogen suppresses symptoms. The effects of sex steroids on the immune system are therefore covered in the book. Sex steroids have been implicated in the pathogenesis of several types of cancers. Synthetic steroid antagonists, such as tamoxifen, have been widely studied as therapeutic agents for hormone-dependent cancers. Hormone replacement therapy (HRT) has been shown to have a number of beneficial effects. In particular, HRT reduces postmenopausal demineralization of bone, thus slowing the advance of osteoporosis. Protective effects of HRT on cardiovascular disease have also been reported. The advantages and disadvantages of HRT therefore form a major topic of discussion in the book.