Stimulates smooth muscle contraction (By similarity). Induces sighing by acting directly on the pre-Botzinger complex, a cluster of several thousand neurons in the ventrolateral medulla responsible for inspiration during respiratory activity (PubMed:26855425). Contributes to the induction of sneezing following exposure to chemical irritants or allergens which causes release of NMB by nasal sensory neurons and activation of NMBR-expressing neurons in the sneeze-evoking region of the brainstem (PubMed:34133943). These in turn activate neurons of the caudal ventral respiratory group, giving rise to the sneeze reflex (PubMed:34133943). Contributes to induction of acute itch, possibly through activation of the NMBR receptor on dorsal root ganglion neurons (PubMed:30734045). Increases expression of NMBR and steroidogenic mediators STAR, CYP11A1 and HSD3B1 in Leydig cells, induces secretion of testosterone by Leydig cells and also promotes Leydig cell proliferation (By similarity). Plays a role in the innate immune response to influenza A virus infection by enhancing interferon alpha expression and reducing expression of IL6 (PubMed:31601264). Plays a role in CSF1-induced proliferation of osteoclast precursors by contributing to the positive regulation of the expression of the CSF1 receptor CSF1R (PubMed:28780306). In neurons of the retrotrapezoid nucleus//parafacial respiratory group, expressed on neuron projections which project into the pre-Botzinger complex. In the hindbrain, expressed in the medulla surrounding the lateral half of the facial nucleus (PubMed:26855425). Also expressed in the olfactory bulb and hippocampus (PubMed:26855425). Detected in a subset of neurons distributed throughout the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) (PubMed:26855425). Within the RTN/pFRG, expressed in neuronal subpopulations distinct from those expressing Grp (PubMed:26855425). Expressed in lung (PubMed:31601264). During osteoclast development, expression increases as the cells differentiate with high expression levels in mature osteoclasts (at protein level). Up-regulated in lung tissue in response to infection with influenza A virus. Significant reduction in the sneezing response to capsaicin at both low and high doses but does not affect pain-related nose wiping behavior or apnea induced by capsaicin (PubMed:34133943). Abolishes the sneezing response to histamine, seratonin and the neuropeptide Npff (PubMed:34133943). Abolishes sneezing response to mast cell-dependent allergy (PubMed:34133943). Belongs to the bombesin/neuromedin-B/ranatensin family.