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Effects of intradermal administration of endogenous opioid peptides, β‐endorphin and dynorphin‐A, on scratching behavior in mice
Author(s) -
Hu Eric,
Cremeans Colette M,
Husbands Stephen M,
Ko MeiChuan
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.581.4
Subject(s) - scratching , dynorphin , histamine , dynorphin a , opioid , pharmacology , opioid peptide , endogenous opioid , chemistry , κ opioid receptor , endocrinology , medicine , receptor , physics , acoustics
Several studies have indicated that mu (MOR) and kappa opioid receptors (KOR) have opposite actions in itch scratching responses. The aim of the study was to investigate the functions of MOR‐ and KOR‐preferring endogenous ligands (β‐endorphin vs. dynorphin‐A) in the peripheral nervous system in modulating itch sensation in mice. Two known pruritogens (histamine and serotonin), β‐endorphin, and dynorphin‐A were administered intradermally in the rostral part of the mouse back. The scratching bouts by hind paw motions directed toward the injection site were scored by experimenters who were blinded to dosing conditions. All four ligands dose‐dependently elicited scratching responses following intradermal (ID) administration within a dose range of 0.1 and 100 nmol/site. The analgesic morphine 1 mg/kg attenuated part of ID β‐endorphin‐ and dynorphin‐A‐induced scratching, but it did not affect ID histamine‐ and serotonin‐induced scratching. In contrast, the antipruritic nalfurafine 0.01 mg/kg attenuated part of ID histamine‐induced scratching, but it was not effective in attenuating other three ligand‐elicited scratching. These results suggest that ID histamine elicited itch sensation manifested as scratching responses in mice. However, ID β‐endorphin‐ and dynorphin‐A‐induced scratching may not entirely be related to itch sensation (Supported by grant DA‐013685 and grant NSC‐96‐2413‐H‐004‐019).