University of California researchers have found that a newly discovered protein switch which they named neuropeptide S appears to work in the brain to enhance wakefulness and reduce anxiety in laboratory animals. According to Rainer Reinscheid and his colleagues, the protein could help in the understanding of sleep disorders, anxiety, and depression.
The researchers also discovered that NPS is produced in a previously uncharacterized population of brain cells, perhaps indicating a new and distinct molecular pathway for regulating vigilance.
"Sleep disorders and anxiety affect millions of people," wrote the researchers. "Identifying and understanding the molecular regulators and neurocircuitries that are involved in sleep/wake cycles or arousal and anxious states are keys to the development of therapeutic targets for these diseases."
In their studies, Reinscheid and his colleagues sought to understand the function of a protein receptor and its triggering molecule discovered by other researchers, who had determined their structure but not explored their effects. Many such triggering molecules--short proteins called neuropeptides--exist in the brain and are known to regulate an array of brain functions. The neuropeptides plug into corresponding receptor proteins nestled in the membranes of brain cells, triggering responses in the cells that govern processes from learning to emotional responses.
Studies in rats by Reinscheid and his colleagues revealed that NPS was produced in a few discrete brain regions, particularly in a distinct, previously uncharacterized cluster of cells in the brain region known to regulate arousal and anxiety. The receptor for NPS was widely expressed in many brain regions, found the researchers, including those known to be involved in anxiety. The widespread expression of the receptor suggested that NPS could play a role in a variety of brain functions, concluded the researchers.
When they administered NPS to mice, they found that it produced an increase in locomotor activity; in rats, NPS increased wakefulness and suppressed sleep.