Itch: More than Skin DeepGreaves M.W. · Khalifa N.
aSt. Johns Institute of Dermatology, St. Thomas’ Hospital, London, UK, bSingapore General Hospital, Singapore
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. A classification of itch has been proposed, based on neurophysiological considerations, which stresses the importance of neurogenic and neuropathic itch, and assists in differential diagnosis and selection of treatment. However, more than one class of itch can occur concurrently in the same patient. 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 µ- receptor antagonists and ĸ-receptor agonists (anti-pruritic) is worth exploring.
Correspondence to: Prof. M.W. Greaves
Department of Dermatology, Singapore General Hospital
Singapore 169608 (Singapore)
Published online: September 16, 2004
Number of Print Pages : 7
Number of Figures : 3, Number of Tables : 1, Number of References : 55
International Archives of Allergy and Immunology
Official Journal of the Collegium Internationale Allergologicum
Vol. 135, No. 2, Year 2004 (Cover Date: October 2004)
Journal Editor: R. Valenta, Vienna
ISSN: 1018–2438 (print), 1423–0097 (Online)
For additional information:http://www.karger.com/iaa