Cell-permeant fusion peptides Tat-PDZ can dose-dependently reduce the threshold for anesthesia. PDZ domain-mediated protein interactions at synapses in the central nervous system play an important role in the molecular mechanisms of anesthesia. Moreover, Tat-PDZ cell-permeant fusion peptides are delivered intracellularly into neurons in the central nervous system subsequent to intraperitoneally injection. By in vitro and in vivo binding assays, we found that the Tat-PDZ dose-dependently inhibited the interactions between NMDARs and PSD-95. Furthermore, behavior testing showed that animals given Tat-PDZ exhibited significantly reduced established inflammatory pain behaviors compared to vehicle-treated group. Our results indicate that by disrupting NMDAR/PSD-95 protein interactions, the Tat-PDZ cell-permeable fusion peptides provide a new approach for inflammatory pain therapy.