Stress hormone kicks brain cells into gear

Some brain cells need a jolt of stress to snap to attention. Cells called astroglia help regulate blood flow, provide energy to nearby cells and even influence messages’ movement between nerve cells. Now, scientists report June 18 in Neuron that astroglia can be roused by the stress molecule norepinephrine, an awakening that may help the entire brain jump into action.

As mice were forced to walk on a treadmill, an activity that makes them alert, astroglia in several parts of their brains underwent changes in calcium levels, a sign of activity, neuroscientist Dwight Bergles of Johns Hopkins University School of Medicine and colleagues found. Norepinephrine, which acts as a fight-or-flight hormone in the body and a neural messenger in the brain, seemed to cause the cell activity boost. When researchers depleted norepinephrine, treadmill walking no longer activated astroglia.

It’s not clear whether astroglia in all parts of the brain heed this wake-up call, nor is it clear whether this activation influences behavior. Norepinephrine might help shift brain cells, both neurons and astroglia, into a state of heightened vigilance, the authors write.