Left. Compound muscle action potentials (CMAP) recorded during repetitive stimulation (rsEMGs) in WT, untreated mSCS and mSCS treated with fluoxetine. Decremental responses were seen in mSCS while reduced decremental responses were shown in mSCS (εL269F) with fluoxetine treatment of 7.2 and 9.6µg/g. Middle. εL269F mice with 2.4 µg/g fluoxetine reduced decrement to 13.6±2.5% whereas decrement was 10.3±3.2% with 4.8 µg/g fluoxetine, 4.0±1.7% with 7.2 µg/g fluoxetine, and 2.8±1.0% with 9.6 µg/g treatment, compared with 19.7±2.3% in untreated εL269F mice. Right. To treated δS268F, decrement was 10.9±1.2% after 4.8 µg/g fluoxetine, 6.8±0.5% after 7.2 µg/g, and 4.2±0.6% after 9.6 µg/g treatment, compared with 18.8±3.1% in untreated δS268F mice. n=7; ***p<0.001, all comparisons were analyzed by Student’s t-test.