12(S)-HPETE induces itch-associated scratchings in mice

Abstract The itch-associated responses evoked by intradermal injection of 12( S )-HPETE and leukotriene B 4 were compared in ICR-mice. 12( S )-HPETE and leukotriene B 4 (0.01–0.2 nmol/site) induced scratching of the injected site, respectively; the dose-responses were a peak at 0.05 nmol/site (12( S )-HPETE) or 0.03 nmol/site (leukotriene B 4 ). The scratching response by 12( S )-HPETE (0.05 nmol/site) started within 1 min, peaked in the first 10 min period, had almost subsided by 25 min whereas the effect of leukotriene B 4 peaked in the second 10 min. The effect of leukotriene B 4 is slightly stronger than that of 12( S )-HPETE in 40 min of count. The scratching induced by 12( S )-HPETE was inhibited by capsaicin, naltrexon, and LY255283. These results suggest the possibility that 12-lipoxygenase product can be added to a new member of an endogenous itch mediator in the skin.