Mouse model of touch-evoked itch (alloknesis)

J Invest Dermatol. 2012 Jul;132(7):1886-91. doi: 10.1038/jid.2012.52. Epub 2012 Mar 15.

Abstract

Lightly touching normal skin near a site of itch can elicit itch sensation, a phenomenon known as alloknesis. To investigate the neural mechanisms of alloknesis, we have developed an animal model. Low-threshold mechanical stimulation of the skin normally does not elicit any response in naive C57/BL6 mice. Following acute intradermal (i.d.) injection of histamine in the rostral back, mechanical stimulation 7 mm from the injection site elicited discrete hindlimb scratch bouts directed toward the stimulus. This began at 10 minutes and peaked 20-40 minutes post histamine injection, declining over the next hour. Histamine itself elicited bouts of scratching not associated with the mechanical stimulus, which ceased after 30 minutes. Histamine- and touch-evoked scratching was inhibited by the μ-opiate antagonist naltrexone. Touch-evoked scratching was observed following i.d. 5-HT (5-hydroxytryptamine), a protease-activated receptor (PAR)-4 agonist, and an MrgprC11 agonist BAM8-22, but not chloroquine or a PAR-2 agonist. The histamine H1 receptor antagonist terfenadine prevented scratching and alloknesis evoked by histamine, but not 5-HT, a PAR-4 agonist or an MrgprC11 agonist. In mice with experimental dry skin, there was a time-dependent increase in spontaneous and touch-evoked scratching. This animal model appears to be useful to investigate neural mechanisms of itch and alloknesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal*
  • Histamine / pharmacology
  • Mice
  • Mice, Inbred C57BL
  • Naltrexone / pharmacology
  • Oligopeptides / pharmacology
  • Peptide Fragments / pharmacology
  • Pruritus / etiology*
  • Receptors, Thrombin / physiology
  • Touch*

Substances

  • Oligopeptides
  • Peptide Fragments
  • Receptors, Thrombin
  • bovine adrenal medulla 8-22
  • seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide
  • Naltrexone
  • Histamine
  • protease-activated receptor 4