AIM: Neuropeptide W (NPW) is an endogenous ligand for the receptors GPR7 and GPR8 and is involved in central regulation of energy homeostasis. NPW in the periphery is found in gastric gastrin (G) cells. In the stomach, energy intake is influenced by vagal afferent signals, so we aimed to determine the effect of NPW on mechanosensitive gastric vagal afferents under different feeding conditions.
METHODS: Female C57BL/6 mice (N > 10 per group) were fed a standard laboratory diet (SLD), high-fat diet (HFD) or were food restricted. The relationship between NPW immunopositive cells and gastric vagal afferent endings was determined by anterograde tracing and NPW immunohistochemistry. An in vitro gastro-oesophageal preparation was used to determine the functional effects of NPW on gastric vagal afferents. Expression of NPW in the gastric mucosa and GPR7 in whole nodose ganglia was determined by quantitative RT-PCR (QRT-PCR). The expression of GPR7 in gastric vagal afferent neurones was determined by retrograde tracing and QRT-PCR.
RESULTS: Neuropeptide W immunoreactive cells were found in close proximity to traced vagal afferents. NPW selectively inhibited responses of gastric vagal tension receptors to stretch in SLD but not HFD or fasted mice. In the nodose ganglia, GPR7 mRNA was specifically expressed in gastric vagal afferent neurones. In fasted mice gastric mucosal NPW and nodose GPR7, mRNA was reduced compared with SLD. A HFD had no effect on gastric NPW mRNA, but down-regulated nodose GPR7 expression.
CONCLUSION: Neuropeptide W modulates gastric vagal afferent activity, but the effect is dynamic and related to feeding status.
