Tachykinin Receptors
The tachykinin peptides constitute one of the largest peptide families. To date, more than 40 tachykinins have been identified from invertebrate and vertebrate species. In mammals, three prototypical tachykinins have been isolated from neuronal tissue: substance P, neurokinin A and neurokinin B. Recently hemokinin-1 has been isolated from murine blood cells and identified as a new endogenous tachykinin. Three main tachykinin receptor types have been identified: NK1, NK2 and NK3 receptors.
Receptor Data
Tachykinin Receptor Data
| Receptor Subtype | NK1 | NK2 | NK3 |
|---|---|---|---|
| Transduction Mechanism | Activates Gq/11 | Activates Gq/11 | Activates Gq/11 |
| Localization | CNS (particularly the striatum, amygdala and some hypothalamic and thalamic nuclei), peripheral tissues | Periphery (inflammatory cells and bronchial, gastrointestinal and urinary smooth muscle), limited expression in the CNS | CNS (hippocampus, hypothalamus, substantia nigra, dorsal horn of the spinal cord), limited expression in the periphery |
| Preferred Endogenous Ligand | Substance P (1156) > Neurokinin B (1582) | Neurokinin B (1582) > Substance P (1156) | Neurokinin B (1582) > Substance P (1156) |
| Selective Agonists | GR 73632 (1669) [Sar9,Met(O2)11]-Substance P (1178) | GR 64349 (1668) | Senktide (1068) |
| Selective Antagonists | FK 888 (2400) L-733,060 (1145) RP 67580 (1635) SDZ NKT 343 (2394) | SB 222200 (1393) |