Specific primary antibody

Membrane fractions were resolved on ice by SDS-PAGE on 4–12% Tris-glycine gels (Invitrogen) and electrophoretically transferred to a PVDF membrane (Immuno-Blot PVDF Membrane, Bio-Rad). Membranes were blocked for 1 hour at room temperature by incubation in 5% bovine serum albumin (Thermo Scientific Pierce) and then incubated overnight at 4 °C with specific primary antibodies (Millipore) against the following proteins: NMDA receptor subunits GluN2A (1:1000, 04–901) and GluN2B (1:1000, 05–920), AMPA receptor subunits GluA1 (1:1000, MAB2263) and GluA2/3 (1:500, 07–598), vesicular glutamate transporter VGluT1 (1:1000, ABN1647), and β-actin (1:1000, Cell Signaling Technology, 3700S). Antigen binding was visualized by incubating membranes for 1 hour at room temperature in secondary fluorescent antibodies (IRDye 800 CW anti-rabbit, 1:5000, LI-COR Odyssey, 926–32211; IRDye 680 CW anti-mouse, 1:5000, LI-COR Odyssey, 926–68070). All antibodies were diluted in blocking solution (1:1 LI-COR Odyssey blocking buffer to 1x PBST). Protein expression was quantified using LI-COR Odyssey imaging and ImageStudio software. Each sample was normalized to its own β-actin expression, and expression for the SO-trained group was normalized to average levels of the FR-trained group within each gel.