What is the primary function of substance P?

Substance P primarily functions as a neurotransmitter that is involved in the transmission of pain signals. It is part of the neuropeptide family and is released by sensory neurons in response to painful stimuli. Once released, substance P binds to its receptors, predominantly in the central nervous system, which helps propagate the sensation of pain and contributes to the inflammatory response. This mechanism plays a crucial role in how organisms perceive and respond to noxious stimuli. Additionally, substance P is implicated in a variety of physiological processes, such as mood regulation and the response to stress, but its most well-documented role remains in pain signaling.