Exogenous as well as endogenous factors

Pathophysiology of #pruritus.

Exogenous as well as endogenous factors released by #immune #cells, #epithelialcells, or endothelial cells induce activation of signal cascades from the periphery via dorsal root ganglia (DRG) and spinal cord to the central nervous system (CNS). Activation of specific areas in the CNS results in perception of itch leading to a scratch response. By a direct axon reflex mechanism, sensory nerve endings release neuropeptides, which may aggravate the itch response by stimulating release of pruritic mediators from MCs, endothelial cells, and epithelial cells. Whether neuropeptides may also trigger the release of antipruritic agents from these cells is only poorly understood.