Mediators and the sensitization pattern of nociceptive and pruriceptive neurons. Sensitizing and activating mediators in the skin are shown for primary
afferent fibers involved in itch and pain processing. Predominantly pruritic mediators are shown in red, algogenic mediators are shown in blue, and
mediators equally involved in pain and itch are shown in yellow. Note that different classes of fibers subserve pain (mechano-sensitive polymodal
nociceptors and mechano-insensitive “sleeping” nociceptors) and itch (histamine-sensitive mechano-insensitive pruriceptors4 and probably mechanosensitive pruriceptors). In the spinal cord, noxious input can induce central sensitization for pain, and pruriceptive input can provoke central sensitization
for itch. Of note is the corresponding pattern of central sensitization to touch by amyloid-β (A-β) fibers (allodynia vs. allokinesis), by A-δ fibers (punctate
Source: Chapter 102. Neurobiology of the Skin, Fitzpatrick's Dermatology in General Medicine, 8e
hyperalgesia vs. punctate hyperkinesis), and by C fibers (histamine-induced pain vs. algogen-induced itch). x1 = inhibitory interneurons ACh =
Katz SI, Gilchrest
BA, Paller AS,
Leffell
DJ, Wolff K.
Fitzpatrick's
Dermatology
Generalbutyric
Medicine,
8e;
2012
Available
acetylcholine;Citation:
ATP = Goldsmith
adenosine LA,
triphosphate;
β-E = β-Endorphin;
CGRP
= calcitonin
gene-related
protein;
GABA =inγ-amino
acid;
Glu
= glutamate;
at:
http://mhmedical.com/
Accessed:
July
31,
2017
GRP = gastrin-releasing peptide; H+ = hydrogen ion; IL = interleukin; KLK = kallikrein; MMP = matrix metallo proteinase; NGF = nerve growth factor;
Copyright ©
2017
McGraw-Hill
Education.
All rights
reserved
PGE2 = prostaglandin
E2;
SP =
substance P;
TNF = tumor
necrosis
factor.349