July 24, 2021

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Science Advances: Calcium can accurately guide blood flow in the brain

An unexpected discovery by Science Advances: Calcium can accurately guide blood flow in the brain

An unexpected discovery by Science Advances: Calcium can accurately guide blood flow in the brain

Science Advances: Calcium can accurately guide blood flow in the brainIt seems that there are two mechanisms working together to ensure that energy in the form of blood enters specific areas of the brain: one is extensive, the other is precise. 

Unlike other parts of the body, there is not enough space in the brain to store energy. Therefore, the brain needs to rely on hundreds of miles of blood vessels to provide fresh energy through the blood. However, until now, people have not known how the brain expresses its need for more energy when its activity increases, and then directs its blood supply to specific hot spots.

Now, researchers at the University of Maryland School of Medicine and the University of Vermont have discovered how the brain communicates with blood vessels when it needs energy, and how these blood vessels respond by relaxing or contracting to direct blood flow to specific brain areas.

The findings of the study were published in the July 21 issue of Science Advances.

Researchers understand how the brain directs energy to itself in complex details, helping to determine what goes wrong in diseases such as Alzheimer’s disease and dementia, in which defective blood flow can predict recognition. Know the obstacles. If the brain does not send blood to where it is needed when it is needed, neurons will become tense. Over time, they will deteriorate, eventually leading to cognitive decline and memory problems.

The large arteries provide nutrients to medium-sized blood vessels called arterioles, and then provide nutrients to the smaller capillaries, which are so small that they can only pass through one blood cell at a time. In a 2017 Nature Neuroscience paper, researchers found that electrical impulses passing through capillaries can guide blood to flow out of medium-sized small arteries that supply large areas of the brain. In this latest paper, the team hopes to study the fine-tuning of blood flowing through the capillaries to see how this precisely regulates the energy supply to the tiny areas of the brain.

“There seem to be two mechanisms that work together to ensure that energy in the form of blood enters specific areas of the brain: one is extensive and the other is precise,” said Dr. Thomas Longden, assistant professor of physiology at the University of Maryland School of Medicine. “The first The mechanism is like a rough sledgehammer method. By controlling the small arteries of medium size, more blood is transported to the vicinity of the increased brain activity, and then the capillary calcium signal ensures fine tuning, allowing the blood to pass through the tiny capillaries. Arrive at the right place at the right time.”

Dr. Longden and his collaborators used a protein that glows green when the calcium content in the cell increases. Thanks to the efforts of Michael Kotlikoff’s team at Cornell University, they were able to turn on this tool in the cells of the lining of blood vessels in mice. Then, the researchers observed the role of calcium in controlling blood flow in the brain’s capillaries through a small window in the brain of these mice. When the cells in the blood vessels receive a signal of calcium influx, they emit a green light. In this way, 5,000 calcium signals per second can be detected in the capillaries of the tiny parts of the brain, which is equivalent to approximately 1,000,000 responses per second in the entire cerebral vascular system.

“Before we used this new technology, there was a completely invisible world of calcium signals in the brain. Now we can see a lot of activity in the brain’s blood vessels: they are constantly firing,” Dr. Longden said.

The research team then analyzed the complex cellular mechanisms behind calcium’s role in guiding blood through the brain’s capillaries. They found that when neurons send out electrical signals, they cause an increase in calcium content in the cells of the lining of blood vessels. The enzyme then detects this calcium and directs the cell to produce nitric oxide. Nitric oxide is a hormone (also a gas) that causes the muscle-like cells around the blood vessels to relax and then expand the blood vessels to allow more blood to flow in.

“The capillaries are traditionally regarded as simple tubes of red blood cells and a barrier between the blood and the brain,” said co-senior author, Dr. Mark T. Nelson, a distinguished professor at the University of Vermont. “Here, we reveal the calcium signal in the capillaries. The unknown world, like a traffic light, these calcium signals guide important nutrients to nearby active neurons.”

“The first step in finding out what’s wrong with the disease is to determine how the system works. Now that researchers have a grasp of how this process works, they can start studying how blood flow in Alzheimer’s disease and dementia is. Is destroyed, and find a solution to it.

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