Rat anti substance P antibody, clone NC1/34 recognizes the COOH terminal region of substance P, an eleven amino acid polypeptide neurotransmitter derived by proteolytic cleavage of protachykinin-1. Substance P binds to and activates the neurokinin-1 receptor. Substance P is a highly conserved neurotransmitter expressed throughout the animal kingdom. It is highly expressed in the spinal cord dorsal horn and dorsal root ganglia, but not in the ventral horn (Ribeiro-da-Silva andT Hökfelt 2000). It is also expressed in non-neuronal cells including microglia and other immune cells.Substance P has a role in several physiologic activities such as pain transmission, the vomiting reflex, salivary secretion and smooth muscle contraction (Hökfelt 2004).Rat anti substance P antibody, clone NC1/34 demonstrates ~5% reactivity with eledoisin a neurotransmitter identified in the octopus Genus Eledone. It does not react with Leu or Met-enkephalin, somatostatin or beta-endorphin in tested applications.