Substance P is a neuropeptide that functions as a neurotransmitter in the nervous system. It is primarily involved in the transmission of pain signals from peripheral tissues to the central nervous system. This peptide is found in various regions of the brain and spinal cord, playing a crucial role in the perception of pain and inflammatory responses. In addition to its role in pain signaling, Substance P is also associated with other physiological processes, including mood regulation and stress response. It interacts with neurokinin-1 receptors, which are found throughout the body, influencing various functions such as anxiety, nausea, and immune responses.