Effect of Disrupting N -Methyl-d-aspartate Receptor–Postsynaptic Density Protein-95 Interactions on the Threshold for Halothane Anesthesia in Mice

Abstract

Background The authors' previous studies have shown that clinically relevant concentrations of inhalational anesthetics dose-dependently and specifically inhibit the PSD-95, Dlg, and ZO-1 (PDZ) domain-mediated protein interactions between postsynaptic density protein 95 (PSD-95) and N-methyl-d-aspartate receptors, and that the knockdown of spinal PSD-95 by intrathecal injection of PSD-95 antisense oligodeoxynucleotide significantly reduces the minimum alveolar anesthetic concentration for isoflurane in rats. Methods The authors constructed a fusion peptide, Tat-PSD-95 PDZ2, comprising the second PDZ domain of PSD-95, which can specifically disrupt PSD-95 PDZ2-mediated protein interactions by binding to its interaction partner. By intraperitoneal injection of this fusion peptide into mice, the authors investigated the effect of disrupting the PSD-95 PDZ2-mediated protein interactions on the threshold for halothane anesthesia. Results Systemically injected fusion peptide Tat-PSD-95 PDZ2 was delivered into the central nervous system, disrupted the protein-protein interactions between N-methyl-d-aspartate receptor NR2 subunits and PSD-95, and significantly reduced the minimum alveolar anesthetic concentration and righting reflex EC50 for halothane. Conclusions By disrupting PSD-95 PDZ2 domain-mediated protein interactions, intraperitoneal injection of cell-permeant fusion peptide Tat-PSD-95 PDZ2 dose-dependently reduces the threshold for halothane anesthesia. These results suggest that PDZ domain-mediated protein interactions at synapses in the central nervous system might play an important role in the molecular mechanisms of halothane anesthesia.