The “transit” of red blood cells contributes to changes in brain oxygenation


The researchers found that the “transit” of red blood cells (upper gray bar) appears to contribute to fluctuations in oxygenation (white line), which do not correlate with changes in neuronal activity (lower blue peaks) in the brain. mice (top right). Credits: Drew Lab and Yongsoo Kim Lab

Adequate blood flow supplies oxygen and nutrients to the brain, but oxygenation tends to fluctuate differently and consistently. However, the root of this varied activity is not misunderstood.

Now, Penn State researchers have identified one of the causes of the fluctuations: the chance inherent in the flow of red blood cells through tiny blood vessels called capillaries. According to the researchers, this randomness could have potential implications for understanding the underlying biological accumulation mechanisms. , such as Alzheimer’s disease. They published their findings in PLOS Biology today.

“These oxygenation fluctuations also occur in other tissues, such as muscle,” said Patrick Drew, Huck’s distinguished associate professor of Science and Mechanics of Engineering, Neurosurgery, and Biomedical Engineering. “The question we had was: are these fluctuations caused by neural activity or something else?”

Fluctuations resemble noise similar to 1 / f, a statistical pattern that shows large fluctuations composed of many small fluctuations and that occur naturally in a variety of phenomena, from stock prices to river heights. The researchers investigated the fluctuations in mice because of the similarities in their brains with humans, according to Drew, who is also associate director of the Penn State Neuroscience Institute.

First, the researchers controlled the , oxygenation and electrical signals produced by “The first time the last two had been crawled simultaneously, according to Drew, in awake mice.” They collected the data while the mice moved on a spherical tape for up to 40 minutes at a time.

Next, to investigate the relationship between brain activity and fluctuations in oxygenation, the researchers used pharmacological compounds to temporarily and reversibly silence neural signals from the brains of mice. Despite the silence, fluctuations continued, showing little correlation between and oxygenation.

The passage of red blood cells, however, told a different story. Using two-photon laser scanning microscopy, an imaging technique used to visualize cells in the background of living tissue, the researchers were able to visualize the passage of individual red blood cells through the capillaries. lars.

“It’s like traffic,” Drew said. “Sometimes there are a lot of cars passing by and traffic is blocked and sometimes not. And red blood cells go anyway when they approach a crossroads, so this random flow can cause bottlenecks and stops at ship. “

Important in a allowed researchers to perform additional simulations and make inferences based on massive amounts of data produced by the model. The researchers found that these random stops of red blood cells contributed to fluctuations in oxygenation, supporting a relationship between the flow of oxygen. through capillaries and small changes in oxygenation that formed larger trends.

A better understanding of blood flow regulation and subsequent oxygen transport may help researchers improve medical technology and explore causes of diseases such as Alzheimer’s, according to Drew. While researchers identified the link between red for cell transport and oxygenation, more research is needed to investigate additional contributors to oxygenation fluctuations that could play a role in neurodegenerative diseases.

Kyle Gheres, a in the postgraduate program in cell biosciences and molecular integrators, he also contributed to this work. Qingguang Zhang, assistant professor of research in scientific and mechanical engineering, was the first author of the paper. This work was supported by the National Institutes of Health.

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