Endogenous neuropeptide S tone influences sleep-wake rhythm in rats

In this study, we examined the effects of the NPS receptor antagonist [D-Cys(tBu)5]NPS (2 and 20 nmol, icv) on physiological sleep and spontaneous locomotor behavior. The higher dose of [D-Cys(tBu)5]NPS decreased the amount of time spent in wakefulness [control 782.5 ± 25.5 min, treatment 751.7 ± 28.1 min; p < 0.05] and increased the time spent in NREMS [control 572.6 ± 17.2 min, treatment 600.2 ± 26.1 min; p < 0.05]. There was no statistically significant difference in time spent in REMS. There were no behavioral changes including abnormal gross motor behavior in response to [D-Cys(tBu)5]NPS administration. Collectively these data suggest an involvement of the endogenous NPS/NPS receptor system in physiological sleep architecture.