Itch is triggered by somatosensory neurons expressing the ion channel TRPV1 (transient receptor potential cation channel subfamily V member 1). Neuropeptide natriuretic polypeptide b (Nppb) is expressed in a subset of TRPV1 neurons and research has found that Nppb lesioned mice selectively lose almost all behavioral responses to itch-inducing agents. Itch responses are blocked by toxin-mediated ablation of Nppb-receptor expressing cells, but a second neuropeptide, gastrin-releasing peptide (Bombesin-SAP, Cat #IT-40), still induces strong responses in the toxin-treated animals. Nppb-SAP eliminates cells expressing neuropeptide natriuretic polypeptide b (Nppb or BNP) receptor.
Nppb-SAP is a bonded toxin between mouse BNP-32 and the secondary conjugate Streptavidin-ZAP containing the ribosome-inactivating protein, saporin. It eliminates Nppb-receptor expressing cells.