Bioethics Blogs

Exercise Releases Brain-Healthy Protein

We all know that exercise is important for a strong and healthy body. Less appreciated is that exercise seems also to be important for a strong and healthy mind, boosting memory and learning, while possibly delaying age-related cognitive decline [1]. How is this so? Researchers have assembled a growing body of evidence that suggests skeletal muscle cells secrete proteins and other factors into the blood during exercise that have a regenerative effect on the brain.

Now, an NIH-supported study has identified a new biochemical candidate to help explore the muscle-brain connection: a protein secreted by skeletal muscle cells called cathepsin B. The study found that levels of this protein rise in the blood of people who exercise regularly, in this case running on a treadmill. In mice, brain cells treated with the protein also exhibited molecular changes associated with the production of new neurons. Interestingly, the researchers found that the memory boost normally provided by exercise is diminished in mice unable to produce cathepsin B.

Neurons

Caption: After running in a wheel, adult mice form new neurons (green) in the brain’s dentate gyrus.
Credit: Henriette van Praag and Linda Kitabayashi

The findings, published recently in Cell Metabolism, are from a team of researchers led by Hyo Youl Moon and Henriette van Praag of NIH’s National Institute on Aging. The team set out to find proteins that muscle cells secrete during exercise that could be transported to the brain [2]. The researchers began by treating muscle cells in lab dishes with a chemical called AICAR, which mimics the effects of exercise on muscle and boosts running endurance in inactive mice [3].

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.