Discovery of brain blood flow sensor could aid treatment of high blood pressure and dementia

A study by UCL researchers has discovered the mechanism that allows the brain to monitor its own blood supply, a discovery in rats that can help find new treatments for human conditions, including hypertension (pressure high blood pressure) and dementia.

For decades, scientists have suspected that the brain had a way to monitor and regulate its own blood flow independent of the body-wide blood pressure control system, but so far no one has. proved.

The brain needs more blood than any other organ to meet the ceaseless and high demand for oxygen from neurons, so it makes sense that it would have a way of protecting itself from fluctuations in blood flow in the larger body. Disturbances in cerebral blood flow are a known cause in many diseases – for example, a sustained reduction in cerebral blood flow is a likely cause of cognitive decline, dementia, and neurodegenerative diseases such as Alzheimer’s disease.

In a study published in Nature Communications, researchers from UCL, the University of Auckland and the University of Bristol, have found a new function for glial cells in the star-shaped brain, called astrocytes. These cells function as specialized cerebral blood flow sensors that work to self-protect the brain from potentially damaging reductions in blood supply.

Astrocytes are strategically positioned between the blood vessels of the brain and important nerve cells, which control the heart and peripheral circulation, ultimately determining blood pressure.

In the laboratory study in rats, the researchers found that the decrease in cerebral blood flow led to the release of a chemical signal by astrocytes, which stimulated specialized nerve cells to increase blood pressure and restore / maintain blood flow (and oxygen supply) to the brain.

Professor Alexander Gourine (UCL Division of Biosciences), who led the study, said: “We are very excited about this observation: there has never been a formal description of a blood flow sensor or blood pressure in the brain before.

“Our new data identifies astrocytes as sensors of cerebral blood flow which are of crucial importance to define the level of systemic blood pressure (arterial) and, in doing so, to ensure that the brain receives a sufficient quantity of oxygen and nutrients to support the uninterrupted functioning of information. processing machines. “

Co-author Professor Julian Paton (University of Auckland) said: “These astrocyte cells are extremely sensitive to reductions in cerebral blood flow. When blood supply is reduced, they release a chemical signal to the cells Neighboring nerves that increase blood pressure, restoring blood flow to the brain. What we have discovered is that the brain has an automatic way of ensuring that the brain’s blood flow is preserved.

“Unfortunately, in pathological conditions, this happens at the expense of generating higher blood pressure in the rest of the body. This suggests that increased cerebral blood flow by reducing activity in these astrocyte detection cells blood flow can be a way to lower blood pressure in people with hypertension. It can also be a way to fight migraines and strokes. On the other hand, raising awareness of these cells can help in dementia conditions to improve the blood circulation of the brain. “

The corresponding author, Dr. Nephtali Marina-Gonzalez, (UCL Medicine Division), said: “In disease situations where blood supply to the brain is reduced, the mechanisms we describe can react in a way excessive, causing migraines, high blood pressure and strokes. The identity of the cerebral blood flow sensor will allow research into new targeted treatment strategies to relieve these diseases. “

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The study was funded by Wellcome, the British Heart Foundation and in part the New Zealand Health Research Council.

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