Spontaneous and histamine-induced scratching in naked mole-rats compared to laboratory mice. A, Mice and naked mole-rats use their back legs to scratch their bodies at a low spontaneous level. The bar graph shows the average number of bouts of scratching observed over 20 minutes (n = 16 mice; 16 naked mole-rats). B, Histamine is not pruritogenic in naked mole-rats. For mice, 10 μg histamine failed to evoke scratching, but higher doses (20 μg - 4.6 mg) evoked pronounced scratching. In contrast, none of the doses tested induced scratching in naked mole-rats.
Smith et al. Molecular Pain 2010 6:29 doi:10.1186/1744-8069-6-29