TC-2559 enhanced the frequency of sIPSCs in the superficial dorsal horn of the spinal cord slices. A, Whole-cell Patch-clamp recording of sIPSCs in a substantia gelatinosa (SG) neuron in the presence of 15 μM DNQX before and during bath application of 2 μM TC-2559. The holding voltage is -70 mV. B-C, Normalized rate histogram showing the sIPSC frequency (B) and amplitude (C) before and during bath application of 2 μM TC-2559. D-E, Application of TC-2559 (2, 10 μM) significantly enhanced the frequency of sIPSCs, but not the amplitude. *P < 0.05 (paired t test).