A, The application of the noncompetitive NMDA receptor antagonist MK-801 (300 μm) did not reverse the increase in 5-HT output induced by DOI 100 μm (n = 7). B,Antagonism by the AMPA–KA antagonist NBQX (300 μm) of the effect of DOI (n = 7). C, The mGluR 2/3 agonist 1S,3S-ACPD (300 μm, filled triangles; 1 mm,filled circles; n = 5 each) reversed the 5-HT elevation induced by DOI. D, The perfusion of 300 μm AMPA elevated the 5-HT similarly to DOI (n = 6; filled circles). The effect of DOI alone is shown by a dotted line.+p < 0.05 versus baseline (DOI or AMPA); *p < 0.05 versus DOI alone (DOI + drug); Duncan test post-ANOVA.