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Can estrogen therapy after menopause protect your brain from diseases like Alzheimer’s? Nobody had thought of a possible connection between the two until now. A new study published in the journal Brain has however found that estrogen deprivation that follows surgical menopause may lead to a two fold increase in the cognitive decline of the brain. It may not only lead to dementia but also increase the likelihood of the patient developing neurological diseases like Alzheimer’s disease. The study was led by researchers working at the Medical College of Georgia at Georgia Regents University.
The experiment on rats
For their study, the researchers removed the ovaries and uterus of experimental rats in the laboratory. This led the rats to experience surgical menopause characterized by a sharp decline in their estrogen levels. Surgical menopause is the term used for a condition which mimics the characteristics of a natural menopause after the subject has undergone surgical removal of the ovaries along with or without the uterus.
The rats that had undergone the surgical procedure were either immediately put on low dose estrogen therapy, were put on estrogen therapy ten weeks after the procedure, or were never given estrogen. They were examined 10 weeks after removal of their estrogen producing ovaries.
The researchers created stroke like condition in the hippocampus region of the brain of the rats. Hippocampus is the center of memory and learning in the brain.
A part of hippocampus, called as CA3, which is normally resistant to stroke also showed signs of damage.
The researchers were astonished to observe that apart from the damage, the rats which received estrogen either late or never, exhibited an abnormal level of production of certain proteins which are characteristic of diseases of cognitive decline, like Alzheimer’s disease. The production of these proteins was especially marked in the CA3 region of the hippocampus. This part of the brain also became hypersensitive to the toxic beta amyloid proteins found in Alzheimer’s disease.
The researchers have linked the increased brain damage and excessive production of disease related proteins to the increased production of free radicals in the brain. They were able to reduce the extent of brain damage by suppressing the production of free radicals.
Researchers found that prolonged estrogen deprivation following surgical menopause increased the sensitivity of the brain to ischemic stress. This was especially true for the normally stress resistant CA3 region of the hippocampus.
- “Hypersensitivity of the hippocampal CA3 region to stress-induced neurodegeneration and amyloidogenesis in a rat model of surgical menopause,” by Quan-guang Zhang, et al, published on March 9, 2013 in the journal Brain, accessed on April 18, 2013
- “Early surgical menopause linked to declines in memory and thinking skills,” by Bove R. et al, presented at the American Academy of Neurology's 65th Annual Meeting in San Diego, March 21, 2013, accessed on April 18, 2013
- “C terminus of Hsc70-interacting protein (CHIP)-mediated degradation of hippocampal estrogen receptor and the critical period hypothesis of estrogen neuroprotection,” by Q. Zhang, et al, published in 2011 in the Proceedings of the National Academy of Sciences, accessed on April 18, 2013.
- Photo courtesy of hadesigns on Flickr: www.flickr.com/photos/hadesigns/6351044761
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