Brain protein peps up and soothes rodents.

A recently identified brain hormone increases wakefulness and appears to suppress fear when it's injected into rodents. The protein could lead to drugs for narcolepsy, sleepiness, or anxiety, suggest its discoverers, who dubbed the chemical neuropeptide S.

Researchers detected neuropeptide S several years ago, after they had surmised its molecular form from the shape of a receptor for the hormone on the surfaces of certain cells in brain, thyroid, and a few other tissues.

To learn about the hormone's biological function, pharmacologists Yan-Ling Xu and Rainer K. Reinscheid of the University of California, Irvine and their colleagues there and at the Scripps Research Institute in La Jolla, Calif., measured how much of it is made in various parts of the body: They found that certain brain cells, including some adjacent to neurons that make adrenaline, are among the most active producers of the hormone.

Since adrenaline influences arousal and anxiety, the researchers injected neuropeptide S into the brains of live mice to study its behavioral effects. The mice that received such injections displayed less anxiety in novel environments and moved about more than did mice that got inert injections.

The researchers also gave the injections to rats fitted with brain-activity monitors. Those receiving neuropeptide S were more likely to stay awake or to sleep only lightly during the subsequent hour, the scientists report in the Aug. 19 Neuron.

The recent discovery of another neuropeptide, called orexin or hypoeretin, has led to advances in narcolepsy research (SN: 6/19/04, p. 394), but it has yet to yield new drugs for the condition.