Women who enter menopause prematurely after bilateral ovariectomy may have a significantly increased risk for cognitive decline and dementia, according to a study published online ahead of print March 9 in Brain. The investigators studied rats 10 weeks after they had undergone bilateral ovariectomy and found that long-term estrogen deprivation dramatically increased the hippocampal CA3 region's sensitivity to ischemic stress, which correlated with a worse cognitive outcome. Long-term ovariectomized rats had robust hyperinduction of Alzheimer's disease-related proteins in the CA3 region. Following ischemic stress, amyloid-precursor protein processing switched from nonamyloidogenic to amyloidogenic. Replacement of 17β-estradiol at the end of the estrogen-deprivation period could not prevent CA3 hypersensitivity and amyloidogenesis, but if 17β-estradiol was initiated at ovariectomy and maintained throughout the estrogen deprivation period, it completely prevented these events.
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