News: Researchers from the University of Tsukuba have found new evidence of brain refreshing that takes place during rapid eye movement (REM) sleep – a specific phase of sleep when you tend to dream a lot.
Tsukuba-led team directly visualized the movement of red blood cells in the brain capillaries (where nutrients and waste products are exchanged between brain cells and blood) of non-anesthetized mice during awake and asleep states.
Researchers used a dye to make the brain blood vessels visible under fluorescent light using a technique known as two-photon microscopy. They also measured electrical activity in the brain to identify REM sleep, non-REM sleep, and wakefulness, and looked for differences in blood flow between these phases.
“There was a massive flow of red blood cells through the brain capillaries during REM sleep, but no difference between non-REM sleep and the awake state, showing that REM sleep is a unique state” says senior author of the study Professor Yu Hayashi.
Researchers repeated the experiments in mice with and without adenosine A2a receptors (the receptors whose blockade makes you feel more awake after drinking coffee), there was less of an increase in blood flow during REM sleep, even during rebound REM sleep.
“These results suggest that adenosine A2a receptors may be responsible for at least some of the changes in blood flow in the brain during REM sleep,” says Professor Hayashi.
These results are interesting and help in understanding the function of sleep. The findings have important implications for developing treatments for neurodegenerative diseases that involve the buildup of waste products in the brain, such as Alzheimer’s disease.
To Know More You May Refer To
Tsai, C., Nagata, T., Liu, C., Suganuma, T., Kanda, T., Miyazaki, T., Liu, K., Saitoh, T., Nagase, H., Lazarus, M., Vogt, K. E., Yanagisawa, M., & Hayashi, Y. (2021). Cerebral capillary blood flow upsurge during REM sleep is mediated by A2a receptors. Cell Reports, 36(7), 109558. https://doi.org/10.1016/j.celrep.2021.109558