Tachykinins are a family of neuropeptides that are widely distributed in the central and peripheral nervous systems of various animal species, including humans. They are responsible for regulating a diverse range of physiological processes, especially in the immune, respiratory, gastrointestinal, and cardiovascular systems.
These neuropeptides are characterized by a conserved amino acid sequence at their C-terminal end, which is typically preceded by a variable N-terminal region. The most extensively studied tachykinins include substance P (SP), neurokinin A (NKA), and neurokinin B (NKB). These tachykinins exert their biological effects through binding to specific receptors called tachykinin receptors.
Tachykinin receptors belong to the superfamily of G-protein coupled receptors (GPCRs). They are classified into three major subtypes: NK1, NK2, and NK3 receptors. Each subtype demonstrates a distinct tissue distribution and affinity for different tachykinins, allowing for specificity in their physiological actions.
The activation of tachykinin receptors initiates a cascade of intracellular events, leading to various physiological responses. Some of the effects of tachykinins include modulation of pain perception, inflammation, smooth muscle contraction, neuronal excitability, and neurotransmitter release.
Due to their involvement in several physiological pathways, tachykinins and their receptors have been targeted for therapeutic interventions in several diseases, including asthma, inflammatory bowel disease, schizophrenia, and certain types of cancers.
In conclusion, tachykinins are neuropeptides that play a crucial role in regulating various physiological processes through their binding to specific tachykinin receptors. Understanding their functions and mechanisms of action is essential for the development of targeted therapies for a range of diseases.
