H4R antagonists can also inhibit scratching in mice induced by substance P, haptens, and in models of dermatitis (Rossbach et al., 2009; Yamaura et al., 2009; Cowden et al., 2010b; Suwa et al., 2011; Ohsawa and Hirasawa, 2012). This evidence concerns the gene HRH4 and skin disorder.