Acta dermato-venereologica
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Acta Derm. Venereol. · Feb 2015
Nalfurafine suppresses pruritogen- and touch-evoked scratching behavior in models of acute and chronic itch in mice.
The kappa-opioid agonist, nalfurafine, has been approved in Japan for treatment of itch in patients with chronic kidney disease. We presently investigated if systemic administration of nalfurafine inhibited ongoing or touch-evoked scratching behavior (alloknesis) following acute intradermal injection of histamine or the non-histaminergic itch mediator, chloroquine, in mice. We also investigated if nalfurafine suppressed spontaneous or touch-evoked scratching in an experimental model of chronic dry skin itch. ⋯ Following acute histamine, but not chloroquine, low-threshold mechanical stimuli reliably elicited directed hindlimb scratching behavior, which was significantly attenuated by nalfurafine. In mice with experimental dry skin, nalfurafine abolished spontaneous scratching but had no effect on alloknesis. Nalfurafine thus appears to be a promising treatment for acute itch as well as ongoing itch of dry skin.
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Acta Derm. Venereol. · Jan 2015
Randomized Controlled Trial Comparative StudyGender differences in itch and pain-related sensations provoked by histamine, cowhage and capsaicin.
Cowhage, capsaicin and histamine, all applied via spicules, were used to induce itch and pain-related sensations in 15 male and 15 female subjects. Sensory qualities were assessed by questionnaire; intensities and time courses of the "itching" and "burning" sensation were measured alternately, but continuously on a VAS. In addition, axon reflexes were assessed. ⋯ Female subjects experienced more pain-related sensations (questionnaire), and their ratings leaned more toward burning than those of males. These findings indicate that the mixed itching and burning sensations are differentially processed by both genders. No indications were found for gender specific differential processing in the primary afferents as reflected by nearly identical flare responses.
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Acta Derm. Venereol. · Jan 2015
Increased expression of three types of transient receptor potential channels (TRPA1, TRPV4 and TRPV3) in burn scars with post-burn pruritus.
Post-burn pruritus is a common distressing consequence of burn wounds. Empirical treatment often fails to have a satisfactory outcome on post-burn pruritus, as the mechanism of post-burn pruritus has not been fully elucidated. The aim of this study was to evaluate the manifestation of transient receptor potential (TRP) channels in post-burn pruritus. ⋯ Furthermore, real time- PCR showed that mRNA of TRPA1 and TRPV4 was increased in itching burn scars. Staining for substance P and CGRP did not differ between the 2 grouped, but the former neuropeptide was increased in burn scars. These results may help determine a specific therapeutic approach for post-burn pruritus.