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. 2012 Sep 3;590(Pt 22):5795–5808. doi: 10.1113/jphysiol.2012.238659

Figure 3. Glucocorticoids inhibit AMPAR-EPSCs in putative DR 5-HT neurons by reducing glutamate release.

Figure 3

A, summary graph of dexamethasone (DEX)-induced inhibition of AMPAR-EPSCs elicited by pairs of stimuli with an inter-stimulus interval of 50 ms. Right panel is superimposed averaged pairs of EPSC traces taken at the time points indicated by the numbers in the left panel. Calibration bars: 50 pA, 20 ms. B, summary histogram of the average paired pulse ratio (PPR) of EPSCs obtained in the control condition (n= 6) and the presence of DEX (n= 6, *P < 0.05). Note that the inhibition of EPSCs is accompanied by a significant increase in the PPR. C, summary histogram of the CV determined in the absence and presence of DEX (300 nm). Note that dexamethasone significantly increases the CV (n= 6; *P < 0.05). E, sample graph illustrates sEPSCs recorded in the control condition (left panel) and in the presence of DEX (300 nm, right panel). Calibration bars: 50 pA, 300 ms. F, plots of the cumulative probability curves of the inter-event interval obtained in the control condition (continuous line) and in the presence of DEX (300 nm, dashed line) for the neuron illustrated in E. Note that DEX (300 nm) induces a significant (P < 0.05; K–S test) rightward shift of the cumulative probability curve of the inter-event interval, indicating an inhibition of sEPSC frequency. G, plots of the cumulative probability curves of sEPSC amplitude obtained in the control condition (continuous line) and in the presence of DEX (300 nm; dashed line). Note that DEX has no effect on the amplitude distribution of sEPSCs.