Central Neuropeptide S inhibits distal colonic transit through activation of central Neuropeptide S receptor in mice.

Neuropeptide S (NPS), the endogenous ligand of NPS receptor (NPSR), regulates many biological functions, including arousal, anxiety, locomotion and food intake. NPSR mRNA is expressed in several regions of central autonomic network through which the brain controls visceromotor and other responses essential for survival. However, the role of NPS/NPSR system in regulating gastrointestinal motor is still unknown. Here, we studied the effects of NPS on distal colonic transit in mice. Intracerebroventricular (i.c.v.) injection of NPS (1-1000 pmol) inhibited fecal pellet output and bead expulsion in a dose-dependent manner. However, intraperitoneal injection of NPS (1000 and 10000 pmol) did not affect fecal pellet output and bead expulsion. In vitro, NPS (0.1-10 microM) also did not modulate distal colonic contractions. Furthermore, i.c.v. co-administration of [D-Val(5)]NPS, a pure and potent NPSR antagonist, dose-dependently antagonized the inhibitory effects of NPS on fecal pellet output and bead expulsion. In conclusion, our results firstly indicate that central NPS inhibits distal colonic transit through the activation of central NPSR, which implicate that NPS/NPSR system might be a new target to treat function disorder of distal colon.