From Nature Science Update, 26th.,March,1998 www.nature.com
An article by Helen Phillips in Nature comments on a study published in the latest issue of Neuroscience, which suggests that estrogen seems to protect cells from ageing damage. It has been noticed that hormone replacement therapy was associated with a reduced risk of developing Alzheimer's disease, and a delay in its onset, protecting isolated nerve cells from the effects of certain toxins. Oxidative damage is the main form of ageing damage. The culprit is thought to be a toxic amyloid peptide fragment, and is involved in many neurodegenerative disorders, including Alzheimer's disease. P. S. Green and colleagues from the University of Florida at Gainesville, tested the effect of the peptide on isolated nerve cells in culture. The peptide killed more than half of the cells, but when treated with estrogen, the cells seemed to be protected. The effect was most obvious when the antioxidant chemical glutathione was also added. Alone, this chemical has no effect, but in combination with estrogen, the peptide could do little damage. Estrogen is generally considered to be a hormone, but clearly it has other effects, since the nerve cells involved do not have hormone receptors. The researchers believe that estrogen is acting as an antioxidant, since variants, which are not active as hormones, exhibit the effect. The hope is that hormonally inactive forms of estrogen may be used in combination with other antioxidants as a therapy for neurodegenerative diseases, without affecting secondary sexual characteristics.