Limits...
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: To investigate the neural mechanisms of alloknesis, we have developed an animal model.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.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

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

License
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, □).


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

License
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: To investigate the neural mechanisms of alloknesis, we have developed an animal model.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.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