Spinal and Supraspinal Substance P Antinociception: Synergistic Interaction

Abstract

Substance P (SP) has undergone extensive investigation since it was discovered in the brain and intestine by Von Euler and Gaddum¹. Various findings indicate that SP may act in the central nervous system as a neurotransmitter in sensory neurons.² Although SP was initially thought to produce hyperalgesia,³ many reports indicate that it has antinociceptive properties.^{4, 5, 6} The mechanism by which SP elicits its antinociceptive effects seems to resemble that of opioidinduced anlgesia, since SP-induced analgesia is reported to be antagonized by naloxone.^{4, 6}