Substance P is a neuropeptide, specifically a member of the tachykinin family, that functions as a neurotransmitter and neuromodulator in the central and peripheral nervous systems. It is derived from the precursor protein called preprotachykinin A, which is processed and cleaved to produce the active substance P molecule.
Substance P is primarily known for its involvement in the transmission of pain signals and the regulation of neuroinflammation. It is predominantly found in sensory neurons, including those that transmit pain signals to the brain. Substance P binds to specific receptors called neurokinin-1 receptors, which are abundantly present in the central nervous system, peripheral nerves, and immune cells.
The release of substance P is triggered by various stimuli such as injury, inflammation, and nerve stimulation. Once released, it facilitates the transmission of pain signals by activating and sensitizing nerve fibers. Additionally, substance P can induce vasodilation and promote the release of other pro-inflammatory substances, contributing to the generation of neurogenic inflammation.
Beyond pain transmission, substance P is also implicated in various physiological and pathological processes, including neurogenic inflammation, wound healing, anxiety, depression, and immune modulation. It plays a role in the regulation of gastrointestinal motility, respiratory function, and cardiovascular control.
In summary, substance P is a neuropeptide that acts as a neurotransmitter and neuromodulator, primarily involved in pain transmission and neuroinflammatory responses. Its diverse functions highlight its importance in both normal physiological processes and various disease states.
