Table 1. Pruritogens and receptors in the periphery.
Pruritogen | Source(s) | Receptor(s) in DRG |
---|---|---|
Histamine | Mast cells | H1R, H4R |
BAM8-22 | Proteolytic cleavage of proenkephalin | MrgprC11 |
CQ | Antimalaria medicine | MrgprA3 |
SLIGRL-NH2 | Synthetic peptide or proteolytic cleavage of PAR2 | MrgprC11, PAR2 |
β-alanine | Muscle-building supplement | MrgprD |
Mucunain | Cowhage | PAR2, PAR4 |
Cathepsin S | Immune cells and epithelial cells | PAR2, PAR4 |
Tryptase | Mast cells | PAR2, PAR4 |
5-HT | Mast cells | 5-HT1, 5-HT2 |
ET-1 | Endothelial cells | ETA |
Substance P | Primary sensory neurons | NK1 |
IL-31 | Mainly Th2 lymphocytes | IL-31RA, OSMR |
Imiquimod | Synthetic immunostimulant | TLR7 (controversial) |
Polyinosinic:polycytidylic acid | Synthetic immunostimulant | TLR3 |
Bile acid | Cholestasis | TGR5 |
Lysophosphatidic acid | Cholestasis | Unknown |
Abbreviations: BAM8-22, bovine adrenal medulla 8–22 peptide; CQ, chloroquine; DRG, dorsal root ganglion; ET-1, endothelin-1; IL-31, interleukin-31; 5-HT, serotonin.