Figure 6. An unidentified glycine-binding substrate regulates excitatory synaptic transmission. A, Example mEPSCs from a NAc MSN in the periods of control, perfusion of glycine transporter 1 antagonist ALX 5407 (ALX, 2 μm), coperfusion of ALX (2 μm) and DCKA (20 μm), and wash-out. B, Example mEPSCs from a NAc MSN in the periods of control, perfusion of d-serine (10 μm), and wash-out. C, Example mEPSCs from a NAc MSN in the periods of control (containing 50 μm d-APV), perfusion of glycine (100 μm), and wash-out. D, Example mEPSCs from a NAc MSN in the periods of control, perfusion of DCKA (50 μm), coperfusion of DCKA and glycine (100 μm), and wash-out. E, Summarized data showing that application of ALX did not prevent DCKA-induced inhibition of the frequency of mEPSCs, application of d-serine did not affect mEPSCs, and application of DCKA prevented the glycine-induced increase in the frequency of mEPSCs in NAc MSNs. F, Summarized data showing that none of the above manipulations significantly altered the amplitude of mEPSCs in NAc MSNs. *p < 0.05.