International archives of allergy and immunology
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Recent research in neurophysiology of itch has indicated the existence of itch-dedicated nociceptor neurones. The perception of itch is regulated by tonically inhibitory descending neuronal pathways and nociceptor spinal neuronal circuits. There is at present no convincing evidence of an 'itch centre' in the brain. ⋯ The importance of cross- talk between dermal mast cells and nociceptor nerve terminals, involving cleavage of proteinase-activated receptor 2 by mast cell tryptase, is highlighted. The pruritus of cholestasis is mediated at least in part by opioid peptides synthesized by the liver, and elevated levels of these mediators are found in the plasma and skin of patients with itch due to cholestasis. The combined use of both mu-receptor antagonists and kappa-receptor agonists (anti-pruritic) is worth exploring.