A protein molecule secreted by muscles during exercise boosts the expression of factors that help to protect brain neurons.

Endurance exercise is known to induce production of a protein called irisin and to improve cognitive performance in patients with some neurological conditions, but the mechanism linking these observations has been unclear.

A team led by Michael Greenberg and Bruce Spiegelman at Harvard Medical School in Boston, Massachusetts, observed that irisin levels increased in a brain area associated with learning and memory after mice ran on exercise wheels. When levels of irisin or its progenitor were raised experimentally in the blood and in neurons, genes associated with learning and memory became active in the brain.

Cell Metab. http://doi.org/n8z (2013)