Inhibition of passive cutaneous anaphylaxis-associated scratching behavior by mu-opioid receptor antagonists in ICR mice.

BACKGROUND

Itching in humans is attenuated by mu-opioid receptor antagonists. ICR mice display increases in scratching behavior upon induction of IgE-mediated passive cutaneous anaphylaxis (PCA), or intradermal injection of compound 48/80 or histamine.

METHODS

Cutaneous reactions were induced in ICR mice by IgE-mediated PCA, compound 48/80 and histamine, and the scratching behavior associated with the cutaneous reactions was evaluated.

RESULTS

Naloxone and nalmefene reduced the incidence of scratching behavior associated with PCA. Naloxone also inhibited the induction of scratching behavior caused by compound 48/80 and histamine. Naloxone did not affect the increase in vascular permeability caused by PCA and injection of compound 48/80.

CONCLUSION

Scratching behavior in mice may be induced by a sensation or a mechanism similar to itching in humans and should become a useful model for examining itching in humans.