TRPA1 and Pruritus: Although previous studies demonstrated that formalin is able to activate several TRP channels, including TRPV1 (16), TRPA1 (15), and TRPV4 (17), our results indicated that only TRPA1 activation contributes to low-dose formalin-induced itch in mice, indicating that different TRP channels mediate different behaviors induced by formalin.