The reason why treadmill training can boost memory recall remains an active area of investigation. A couple of proteins have been shown to fuel exercise-induced neuron growth, but a June 23 study in Cell Metabolism presents a new candidate, cathepsin B--one that can be directly traced from the muscles to the brain in mice. Also, after a run, protein levels increased in blood in mice, monkeys, and humans.
"We wanted to cast a wide net. Rather than focus on a known factor, we did a screen for proteins that could be secreted by muscle tissue and transported to the brain, and among the most interesting candidates was cathepsin B," says senior author Henriette van Praag, a neuroscientist at the National Institute on Aging in the United States.