If thinking about life's stresses makes you want to crawl into bed, there may be a reason. New research reveals that a recently discovered brain protein plays a role in both stress management and wakefulness. The findings may lead to new treatments for anxiety and sleep disorders, scientists say.
The protein, neuropeptide S, is a signaling molecule in the brain, but researchers didn't know much else about it. So a team of scientists led by Rainer Reinscheid and Yan-Ling Xu of the University of California, Irvine, began by searching rat brains for the source of the protein. This led them to a previously unmapped collection of cells in an ancient part of the brainstem near the locus coeruleus, an area known to regulate arousal and anxiety. Receptors for neuropeptide S were found in many parts of the brain, including regions known to be involved in anxiety and alertness, the researchers report in the 19 August issue of Neuron.
Following these clues, the team conducted a series of experiments to see how neuropeptide S affected the stress levels and wakefulness of rats. They found that rats injected with the neuropeptide were less anxious about exploring brightly lit areas of their cages than were normal rats, which preferred the safer, enclosed areas. When researchers put marbles into the cages (rats worry about foreign objects), injected rats didn't care as much and buried fewer of the marbles in their bedding.
In addition to calming nerves, a jab of neuropeptide S kicked the rats in high gear. Those injected with the protein stayed awake for almost twice as long as normal rats. When put in a new cage, rats usually inspect it for a time but then get bored and just sit around. But injected rats remained active and kept exploring the cage as if they'd never been there before. “It's genuine arousal, the urge to go out and do something new,” Reinscheid says.
The new work is an important contribution to understanding an old area of the brain, says Craig Berridge of the University of Wisconsin, Madison. And the protein is a good candidate for treating a number of ills, from depression to narcolepsy. “It's not every day that a [protein] is implicated in such important behavioral processes,” he says.