Scalp pruritus involves a complex interaction between different cells, mediators and receptors, most of them are shown above.
PAR-2, proteinase-activated receptor 2; H1R, Histamine 1 receptor; H3R, Histamine 3 receptor; H4R, Histamine 4 receptor; NGF, nerve growth factor; ET-1; TrkA, high-affinity NGF receptor; endothelin-1; ETAR, endothelin receptor A; eCB, endogenous cannibinoids; NT-3, neurotrophin 3; NT-4, neurotrophin 4; LTB4, leukotriene B4; TXA2, thromboxane A2; GRP, gastrin-related peptide; SP, substance P; CGRP, calcitonin gene related peptide; Mrgpr, mas-related G protein-coupled receptor; IL-2, interleukin-2; IL-4, interleukin-4; IL-8, interleukin-8; IL-31, interleukin-31; BDNF: brain-derived neurotrophic factor; EDN, eosinophil-derived neurotoxin; ECP, eosinophil cationic protein; PGD2, prostaglandin D2; ORS, outer root sheath; IRS, inner root sheath; CB1, cannabinoid receptor1; CB2, cannabinoid receptor2; NK1R, neurokinin-1 receptor; TRPV, transient receptor potential vanilloid; MOR, Mu-opioid receptor.