Fig. 5.

Astrocyte-induced increase in mPSC frequency is mediated by NMDA receptors. Shown is the percentage of mechanically stimulated astrocytes that increased the frequency of mEPSCs (left) and mIPSCs (right) in 0.5 mm MAP4 and 0.5 mm MCPG, 10 μmCNQX, 4 mm Mg²⁺, 50 μmAP5, and 50 μm NO-Arg; also shown is the percentage after dialysis of the postsynaptic cell with BAPTA (10 mm in the recording pipette) and in their respective control solution in parallel cultures. In the histograms labeled MK-801 we caused a use-dependent block of NMDA receptors before stimulating astrocytes by incubating the cultures during 5 min in NMDA (200 μm) and MK-801 (5 μm) to cause a sustained block of this receptor subtype (see Results). After washout, astrocyte stimulation no longer modulated mPSC frequency. Significant differences with respect to control were established by the Student’s t test at **p < 0.01; ***p < 0.001.