Published on: December 13, 2015
The hormone estrogen helps protect memory and promote a healthy brain, but this effect wanes as women age, and even estrogen replacement therapy stops working in humans after age 65. Now researchers at University of Florida Health have used gene therapy in a rat model to show that the expression of a particular receptor can reinstate lost memory function.
The scientists, including Thomas C. Foster, Ph.D., a professor of neuroscience and the Evelyn F. McKnight chair for research on cognitive aging, and Linda A. Bean, Ph.D., report their findings in the current edition of The Journal of Neuroscience.
“There is a window of time, starting around menopause, when initiation of hormone replacement therapy with estrogen protects the brain against injury and Alzheimer’s disease. However, this window seems to end around age 65,” Foster said. “We wanted to find out what is regulating this window.”
The researchers used gene therapy to overexpress two different estrogen receptors found in the hippocampus, a part of the brain essential to memory regulation. They found that an abundance of one of these receptors, called alpha, reinstated memory in aging rats when paired with estrogen.
Estrogen helps to do this by increasing the brain’s “plasticity,” which is the ability to form and maintain connections between brain cells as things are learned. As plasticity declines, so do the number of connections in the brain, and certain types of memories begin to fade. Without the protective effect of estrogen, women may lose brain plasticity and start forgetting things more often. The loss of estrogen’s protective effects may explain why women are more likely than men to develop dysfunctional memory problems such as Alzheimer’s disease.
The researchers looked at the effects on memory in six groups, which received gene therapy for expression of the alpha receptor, the beta receptor or a control gene. The three different gene therapy groups then received estrogen or a placebo for the next several weeks, until memory testing and examination of brain plasticity. The project involved 72 animals. Only the group with gene therapy for the alpha receptor plus estrogen showed any beneficial effects on memory and increased brain plasticity markers.
“In the short term, this finding helps us understand how estrogen rescues memory and keeps the brain young and plastic,” Foster said. “In the long term, this finding may eventually allow us to bypass estrogen and target the receptor or brain plasticity mechanisms directly.”
Next steps will include examining the alpha receptor more closely.
“Now that we know this has an effect, we can look for potential ways to treat cognition without hormone replacement,” Foster said.
Thanks to the ongoing support of our partner Brain Canada, and The Citrine Foundation of Canada, Women’s Brain Health Initiative’s newest edition of MIND OVER MATTER has just been published. Loaded with interesting science-based articles, MIND OVER...
On December 2nd, in celebration of Women’s Brain Health Day, join thousands of others and take part in the Stand Ahead® Memory Challenge to stand up against research bias and stand ahead for women’s brain...
YOU’RE INVITED! On December 2nd, the second annual Women’s Brain Health Day, take the memory challenge and help us combat brain-aging diseases that disproportionately affect women. Join CTV’s Pattie Lovett-Reid and Anne-Marie Mediwake, along...
The material presented through the Think Tank feature on this website is in no way intended to replace professional medical care or attention by a qualified practitioner. WBHI strongly advises all questioners and viewers using this feature with health problems to consult a qualified physician, especially before starting any treatment. The materials provided on this website cannot and should not be used as a basis for diagnosis or choice of treatment. The materials are not exhaustive and cannot always respect all the most recent research in all areas of medicine.