RT Journal Article SR Electronic T1 Nerve Injury Increases GluA2-Lacking AMPA Receptor Prevalence in Spinal Cords: Functional Significance and Signaling Mechanisms JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 765 OP 772 DO 10.1124/jpet.113.208363 VO 347 IS 3 A1 Shao-Rui Chen A1 Hong-Yi Zhou A1 Hee Sun Byun A1 Hui-Lin Pan YR 2013 UL http://jpet.aspetjournals.org/content/347/3/765.abstract AB The glutamate α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) are critically involved in the excitatory synaptic transmission, and blocking AMPARs at the spinal level reverses neuropathic pain. However, little is known about changes in the composition of synaptic AMPARs in the spinal dorsal horn after peripheral nerve injury. AMPARs lacking the GluA2 subunit are permeable to Ca2+, and their currents show unique inward rectification. We found that AMPAR-mediated excitatory postsynaptic currents (AMPAR-EPSCs) of spinal dorsal horn neurons exhibited a linear current-voltage relationship in control rats, whereas AMPAR-EPSCs of dorsal horn neurons displayed inward rectification in rats with spinal nerve injury. In nerve-injured rats, compared with control rats, the GluA2 protein level was significantly less in the plasma membrane but was greater in the cytosolic vesicle fraction in the dorsal spinal cord. However, the GluA1 protein levels in these fractions did not differ significantly between nerve-injured and control rats. Blocking N-methyl-d-aspartate receptors (NMDARs) abolished inward rectification of AMPAR-EPSCs of dorsal horn neurons in nerve-injured rats. Furthermore, inhibition of calpain or calcineurin, but not protein kinase C, completely blocked nerve injury–induced inward rectification of AMPAR-EPSCs of dorsal horn neurons. In addition, blocking GluA2-lacking AMPARs at the spinal cord level reduced nerve injury–induced pain hypersensitivity. Our study suggests that nerve injury increases GluA2 internalization and the prevalence of GluA2-lacking AMPARs in the spinal dorsal horn to maintain chronic neuropathic pain. Increased prevalence of spinal GluA2-lacking AMPARs in neuropathic pain is mediated by NMDARs and subsequent stimulation of calpain and calcineurin signaling.