The newly created transgenic rats are the first rodents to have mutations that effectively reproduce those brain changes, according to the research published April 9 in the Journal of Neuroscience.
From studying the genetically engineered rats, the researchers have confirmed the role of amyloid plaques in the development of the disease and discovered specialized glial cells (neural support cells) before the development of amyloid plaque. That suggests that activation of those cells could potentially become a new treatment target, according to Town. "We may be able to see subtle changes in humans earlier than we thought in people who are predisposed to Alzheimer's."
To create a transgenic rat, "you take a disease-causing gene from a human and you put it into an animal," Town explained. "You make a line of animals, just like you would with dogs or horses, to transmit that gene."
The scientists then test to be sure the rat progeny have evidence of the genetic changes and allow them to age. Rats typically have a three-year lifespan, so 16-month-old rats are like people in their 40s and 2-month-olds are like those in their 80s, Town noted.
The researchers tested the transgenic rats to confirm the presence of the neurofibrillary tangles in areas of the brain involved in learning and memory. They also found evidence that 30 percent of the rats' brain neurons in these areas died as the rats aged, with some glial cells forming themselves into shapes similar to those found in human patients.
Heather Snyder, director of medical and scientific operations for the Alzheimer's Association, said the research represents the first time critical processes and pathologies of the disease have been replicated in an animal model. But she warned that animal models are limited.
"Rats are not humans and animals do not develop Alzheimer's," Snyder noted.
"This is something that is still being manipu
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