Acta Dermato-Venereologica (Jun 2017)

Involvement of µ-opioid Receptors and κ-opioid Receptors in Itch-related Scratching Behaviour of Imiquimod-induced Psoriasis-like Dermatitis in Mice

  • Nobuaki Takahashi,
  • Mitsutoshi Tominaga,
  • Ryohei Kosaka,
  • Yayoi Kamata,
  • Yoshie Umehara,
  • Hironori Matsuda,
  • Azumi Sakaguchi,
  • Hideoki Ogawa,
  • Kenji Takamori

DOI
https://doi.org/10.2340/00015555-2704
Journal volume & issue
Vol. 97, no. 8
pp. 928 – 933

Abstract

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The pathogenesis of psoriatic itch is poorly understood. The aim of this study was to investigate the involvement of opioid receptors in scratching behaviour of imiquimod-induced psoriasis-like dermatitis model mice. Topical application of 5% imiquimod cream to the rostral back skin of mice induced antihistamine-resistant scratching behaviour. The expression of µ-opioid receptor (MOR) protein increased in the epidermis, dorsal root ganglia (DRG) and spinal cord of imiquimod-treated mice. In contrast, the expression of κ-opioid receptor (KOR) protein decreased in the DRG and spinal cord of imiquimod-treated mice, and was undetectable in the epidermis of both groups. Topical or intraperitoneal administration of the MOR antagonist naloxone and oral administration of the centrally acting KOR agonist ICI-199,441 inhibited scratching behaviour, whereas oral administration of the peri­pherally-selective KOR agonist asimadoline did not. These results suggest that peripheral and central MOR and central KOR may be involved in the modulation of scratching behaviour in imiquimod-treated mice.

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