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Blood vessel/nitric oxide health may affect Alzheimer's risk
Researchers at the Mayo Clinic have published an intriguing paper explaining why exercise may help reduce the risk of Alzheimer's disease.
For years, exercise has been linked to reduced risk of heart disease and reduced dementia risk.
The study focused on the layer of cells, known as the endothelium, that line the inside of blood vessels. In that lining nitric oxide is produced. Nitric oxide is a crucial chemical that long has been associated with the ability of blood vessels to widen as well as reduced risk of cardiovascular disease.
But it appears to have another function, according to the paper, which was published in Circulation Research, a journal of the American Heart Association.
Using endothelial cells from tiny blood vessels from the human brain, the reseachers chemically inhibited the production of an enzyme needed to produce nitric oxide.
That caused a biochemical reaction that led to an increase in levels of amyloid precursor protein (APP), the basic substance involved in the formation of amyloid plaques that build up around brain cells and are the hallmark of Alzheimer's disease.
The reaction also increased production of another enzyme needed to transform APP into the plaques.
The reseachers also looked at mice that had been genetically engineered to lack the enzyme involved nitric oxide production. Those mice had naturally higher blood pressure, more insulin resistance as well as higher levels of APP.
"There is a lot of literature showing that every time you exercise, you stimulate the endothelium to produce more nitric oxide," senior author Zvonimir Katusic, a professor of anesthesiology and pharmacology at the Mayo Clinic, said in a statement. "What we have identified in this paper may help explain the reported cognitive benefit of exercise."
Katusic noted that a variety of conditions known to increase heart disease risk - high cholesterol, diabetes, hypertension, smoking, sedentary lifestyle and aging - all are associated with reduced levels of nitric oxide in the endothelium.