Fig. 1.
Chronic morphine treatment increases α2δ-1 association with N-methyl-d-aspartate receptors at spinal cord synapses. (A, B) Representative blots and quantification of α2δ-1 protein levels in the dorsal root ganglion (DRG; A) and dorsal spinal cord (B) from vehicle-treated (V) and morphine-treated (M) rats (n = 6 rats in each group). (C) Coimmunoprecipitation (IP) analysis shows that GluN1 coprecipitated with α2δ-1 in the membrane extracts of dorsal spinal cord tissues of rats treated with vehicle or morphine for 8 days (n = 6 rats in each group). The amount of α2δ-1 proteins was normalized to that of GluN1 in the same sample, and the mean α2δ-1 level in vehicle-treated rats was considered to be 1. (D) Representative gel images and quantification of GluN1 and α2δ-1 protein amounts in dorsal spinal cord synaptosomes from vehicle- and morphine-treated rats (n = 6 rats in each group). (E) Coimmunoprecipitation analysis shows the effect of treatment with 1 µM α2δ-1Tat peptide and scrambled control (Cont) peptide on the α2δ-1–GluN1 complex level in spinal cord slices from morphine-treated rats (n = 6 rats in each group). Data are shown as means ± SD. *P < 0.05; **P < 0.01; ***P < 0.001 versus the vehicle or control peptide group. IgG, immunoglobulin G; P(+), with α2δ-1Tat peptide; P(−), without α2δ-1Tat peptide.