Tachykinins

Tachykinins are a family of neuropeptides that play a significant role in the nervous system. The name "tachykinin" comes from the Greek words "tachys" meaning fast and "kinein" meaning to move, reflecting their rapid action on smooth muscle. The most well-known tachykinin is Substance P, but the family also includes neurokinin A, neurokinin B, and others depending on the species.

These peptides are found in both the central and peripheral nervous systems of vertebrates and invertebrates. They are synthesized from precursor proteins and released from nerve terminals in response to various stimuli. Tachykinins exert their effects by binding to specific receptors, primarily neurokinin receptors 1, 2, and 3. These receptors are G protein-coupled receptors, and their activation leads to a cascade of intracellular events.

The functions of tachykinins are diverse and involve a wide range of physiological processes. In the periphery, they are involved in pain transmission, inflammation, and smooth muscle contraction, particularly in the gastrointestinal and respiratory tracts. In the central nervous system, they modulate mood, anxiety, learning, and memory. Their involvement in pain pathways has made them a target for research into pain management therapies. Disruptions in tachykinin signaling have been implicated in various conditions, including inflammatory diseases, neurological disorders, and mood disorders.