Figure 6. Selective activation of 5-HT₄ or 5-HT_2A receptors increases the frequency and amplitude of sEPSCs.

A, effect of 5-HT in the presence of 1 μm MDL 100907 and 1 μm SB-269970 (selective activation of 5-HT₄ receptors). Aa, current trace from a layer V pyramidal neurone showing the effect of bath administration of 30 μm 5-HT. Holding potential, −70 mV; holding current, −25 pA. Ab, administration of 5-HT significantly shifts to the left the cumulative distribution of inter-event intervals indicating that 5-HT significantly increased the frequency of sEPSCs (P < 0.05, K-S test). Ac, amplitude distribution of sEPSCs during baseline acquisition (open bars) and in the presence of 5-HT (filled bars). 5-HT shifts the amplitude distribution of synaptic currents towards larger size classes. The noise distribution is shown as a dashed line. Ad, the cumulative distribution of sEPSC amplitudes (P < 0.05; K-S test) indicates that 5-HT increased the amplitude of sEPSCs. B, effect of 5-HT in the presence of 1 μm GR 113808 and 1 μm SB-269970 (selective activation of 5-HT_2A receptors). Ba, current trace from a layer V pyramidal neurone showing the effect of bath administration of 30 μm 5-HT. Bb, administration of 5-HT significantly shifted to the left the cumulative distribution of inter-events intervals (P < 0.05, K-S test) indicating that 5-HT significantly increased the frequency of sEPSCs. Bc, amplitude distribution of sEPSCs during baseline (open bars) and in the presence of 5-HT (filled bars). 5-HT shifted the amplitude distribution of synaptic currents towards larger size classes. The noise distribution is shown as a dashed line. Bd, the cumulative distribution of sEPSC amplitudes shows that 5-HT increases the amplitude of sEPSCs (P < 0.05; K-S test).