Substance P (Neurokinin P) is a neuropeptide composed of 10 amino acids. The N segment of the peptide is closed by an amide bond, and the peptide is generally hydrophilic. The main physiological role of Substance P is to act as a neurotransmitter and neuromodulator in the central nervous system. At the same time, the endogenous receptor of Substance P is neurokinin 1 receptor (NK1R).