Bombesin and two major bombesin-like peptides in mammals, gastrin-releasing peptide (GRP) and neuromedin B, have been shown to elicit various physiological effects. GRP elicits gastrin release and regulates gastric acid secretion and motor function (Merali et al., 1999). This peptide is also involved in the biology of the circadian system. Interestingly, intradermal injections of GRP elicit scratching in mice (Andoh et al., 2011). GRP is expressed in a subset of peptidergic dorsal root ganglion neurons, whereas GRP receptor (GRPR) is expressed in lamina I of the dorsal spinal cord (Sun and Chen, 2007). When lamina I neurons expressing GRPR in the spinal cord were selectively ablated, the mice showed profound scratching deficits in response to all of the itching stimuli tested, irrespective of their histamine dependence (Sun et al., 2009). These data support the labeled line