Figure 5. PZ-235 inhibits itch evoked by mastoparan-1 and dust mite extract.
(a) Mastoparan-1 (MA-1) was injected intradermally (200 μg in 50 μl H2O) into the dorsal skin of PAR2-knockout and C57BL6 wild-type mice or into (b) wild-type CF1 mice 2 hours after sc PZ-235 (10 mg/kg) or vehicle (n = 10) and total scratching behavior assessed for 5 minutes in C57BL6 mice and 30 minutes for CF-1 mice. (c, d) Itch was quantified in flaky tail mice (n = 6) on the last day of dust mite extract treatment (week 8 from Figure 4) and 2 hours after subcutaneous PZ-235 (5 mg/kg) or vehicle and linearly correlated with lesion severity score. Itching was recorded as scratches of the application site with the hindpaw or by biting and “wet-dog” shakes assessed for a period of 5 minutes, beginning 15 minutes after dust mite extract application. Data for a–c are shown as box and whisker plots, Mann-Whitney test, P < 0.05 or in d, significant (*P < 0.05) Pearson R2 correlation or not significant. ns, not significant; WT, wild type.