Abnormality with special cells that wrap around blood vessels in the brain leads to neuron deterioration, possibly affecting the development of Alzheimer’s disease, a new study reveals.

“Gatekeeper cells” called pericytes surround blood vessels, contracting and dilating to control blood flow to active parts of the brain.

Published in Nature Neuroscience, this was the first study to use a pericyte-deficient mouse model to test how blood flow is regulated in the brain. The goal was to identify whether pericytes could be an important new therapeutic target for treating neuron deterioration.

Pericyte dysfunction suffocates the brain, leading to metabolic stress, accelerated neuronal damage and neuron loss, the researchers say. To test the theory, they stimulated the hind limb of young mice deficient in gatekeeper cells and monitored the global and individual responses of brain capillaries, the smallest blood vessels in the brain. The global cerebral blood flow response to an electric stimulus was reduced by about 30 percent compared to normal mice, denoting a weakened system.

Relative to the control group, the capillaries of pericyte-deficient mice took 6.5 seconds longer to dilate. Slower capillary widening and a slower flow of red blood cells carrying oxygen through capillaries means it takes longer for the brain to get its fuel.

As the mice turned 6 to 8 months old, global cerebral blood flow responses to stimuli progressively worsened. Blood flow responses for the experimental group were 58 percent lower than that of their age-matched peers. In short, with age, the brain’s malfunctioning vascular system exponentially worsens.

The researchers say that their study brings new information to the study of Alzheimer’s disease and ALS. Previous studies have shown that pericytes die in Alzheimer’s and ALS patients, and this study demonstrated that the death of these pericytes restricts blood flow and oxygen to the brain. The next step, they say, will be to try to reveal what kills pericytes in Alzheimer’s and ALS in the first place.

Paper: “Pericyte degeneration leads to neurovascular uncoupling and limits oxygen supply to brain”
Reprinted from materials provided by University of Southern California.

4 Μαΐου, 2017