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Mouse model of touch-evoked itch (alloknesis).

Akiyama T, Carstens MI, Ikoma A, Cevikbas F, Steinhoff M, Carstens E - J. Invest. Dermatol. (2012)

Bottom Line: Histamine itself elicited bouts of scratching not associated with the mechanical stimulus, which ceased after 30 minutes.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA.

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.

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Time-dependent changes in scratch bouts, TEWL and alloknesis score in dry skin mice. The dry skin was developed by treating with AEW twice a day for 12 days. A) TEWL was mesured on the day 0, 1, 3, 5, 8, 10 and 12. Black circle and white square show, respectively, AEW-treated and W-treated groups. B) As in A for Spontaneous scratching. C) As in A for Alloknesis score. Error bars are S.E.M. * p < 0.05, significant difference from day 0.
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Figure 5: Time-dependent changes in scratch bouts, TEWL and alloknesis score in dry skin mice. The dry skin was developed by treating with AEW twice a day for 12 days. A) TEWL was mesured on the day 0, 1, 3, 5, 8, 10 and 12. Black circle and white square show, respectively, AEW-treated and W-treated groups. B) As in A for Spontaneous scratching. C) As in A for Alloknesis score. Error bars are S.E.M. * p < 0.05, significant difference from day 0.

Mentions: TEWL increased significantly on the first day of AEW treatment and reached a plateau by day 3 (Fig. 5A, ●). Spontaneous scratching behavior increased significantly by treatment day 3 (Fig. 5B, ●) and continued to gradually rise. Alloknesis elicited by weak mechanical stimulation at the perimeter of the AEW treatment area increased significantly by day 4 and appeared to reach a plateau (Fig. 5C, ●). There were no significant changes in any of these measures in the control W treatment group (Fig. 5A–C, □).


Mouse model of touch-evoked itch (alloknesis).

Akiyama T, Carstens MI, Ikoma A, Cevikbas F, Steinhoff M, Carstens E - J. Invest. Dermatol. (2012)

Time-dependent changes in scratch bouts, TEWL and alloknesis score in dry skin mice. The dry skin was developed by treating with AEW twice a day for 12 days. A) TEWL was mesured on the day 0, 1, 3, 5, 8, 10 and 12. Black circle and white square show, respectively, AEW-treated and W-treated groups. B) As in A for Spontaneous scratching. C) As in A for Alloknesis score. Error bars are S.E.M. * p < 0.05, significant difference from day 0.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375351&req=5

Figure 5: Time-dependent changes in scratch bouts, TEWL and alloknesis score in dry skin mice. The dry skin was developed by treating with AEW twice a day for 12 days. A) TEWL was mesured on the day 0, 1, 3, 5, 8, 10 and 12. Black circle and white square show, respectively, AEW-treated and W-treated groups. B) As in A for Spontaneous scratching. C) As in A for Alloknesis score. Error bars are S.E.M. * p < 0.05, significant difference from day 0.
Mentions: TEWL increased significantly on the first day of AEW treatment and reached a plateau by day 3 (Fig. 5A, ●). Spontaneous scratching behavior increased significantly by treatment day 3 (Fig. 5B, ●) and continued to gradually rise. Alloknesis elicited by weak mechanical stimulation at the perimeter of the AEW treatment area increased significantly by day 4 and appeared to reach a plateau (Fig. 5C, ●). There were no significant changes in any of these measures in the control W treatment group (Fig. 5A–C, □).

Bottom Line: Histamine itself elicited bouts of scratching not associated with the mechanical stimulus, which ceased after 30 minutes.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA.

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.

Show MeSH
Related in: MedlinePlus