Figure 3.

Tianeptine (TIA)-induced GluA-AMPA receptor (AMPAR) surface diffusion decrease is a Ca²⁺/calmodulin-dependent protein kinase II (CaMKII)-dependent mechanism. (a) Surface GluA2-AMPARs were tracked in the synaptic compartments of days in vitro (DIV) 11–12 cultured hippocampal neurons in the presence/absence of TIA (10 μM) (left panel) and of 100 μM TIA (right panel) with or without CaMKII inhibitor, KN93 (10 μM) (median±25–75% interquartile range (IQR); vehicle=0.06±0.01–0.15 μm² s⁻¹, n=276; TIA (10 μM)+DMSO=0.04±0.01–0.1 μm² s⁻¹, n=210; TIA (10 μM)+KN93=0.08±0.02–0.17 μm² s⁻¹, n=244; ^***P<0.001; right panel: vehicle=0.09±0.03–0.19 μm² s⁻¹, n=198; TIA (100 μM)+DMSO=0.04±0.01–0.13 μm² s⁻¹, n=155; TIA (100 μM)+KN93=0.08±0.03–0.19 μm² s⁻¹, n=173; ^***P<0.001). (b) Ensemble AMPAR mobility was assessed by fluorescence after photobleaching (FRAP) at synaptic compartments in the presence/absence of TIA (10 μM) (left panel) and of TIA (100 μM) (right panel) with or without CaMKII inhibitor, KN93 (10 μM). The decreased GluA1-AMPAR fluorescence recovery induced by TIA (10 or 100 μM) was fully restored in the presence of KN93. (c) Quantified GluA1-AMPARs mobile fraction at synaptic compartments in vehicle, TIA and TIA+KN93 conditions. The mobile fraction was considered as the percentage of fluorescence recovery at the end of FRAP (elapse time 150 s) (left panel: vehicle=64±4.7%, n=26; TIA (10 μM)=40±3.2%, n=21; TIA (10 μM)+KN93=57±3%, n=32; right panel: vehicle=64±4.7%, n=26; TIA (100 μM)=31±3.6%, n=24; TIA (100 μM)+KN93=55±4.4%, n=18; ^**P<0.01; ^***P<0.001). DMSO, dimethylsulfoxide.