Figure 8. The 5-HT-induced increase in sEPSC frequency and amplitude in the adult rat prefrontal cortex is entirely dependent on the activation of 5-HT2A receptors.
A, current traces depicting the effect of 30 μm 5-HT on a layer V pyramidal neurone. Traces 1 and 2 depict current traces plotted using an expanded time. Ba, 5-HT significantly shifted to the left the cumulative distribution of inter-event intervals (P < 0.05, K-S test) indicating that 5-HT significantly increased the frequency of sEPSCs. Bb, amplitude distribution of sEPSCs during baseline acquisition (open bars) and in the presence of 5-HT (filled bars). 5-HT increased the frequency of sEPSCs at all amplitudes and shifted the distribution towards larger size classes. The noise distribution is shown as a dashed line. Bc, the cumulative distribution for sEPSC amplitudes is significantly shifted to the right by 5-HT (P < 0.05; K-S test. Holding potential, −70 mV. Ca, the increase in sEPSC frequency induced by bath administration of 5-HT is blocked by the selective 5-HT2A antagonist MDL 100907 (300 nm). Cb, plot comparing the effect of two consecutive applications of 5-HT on sEPSC frequency. The increase in frequency of sEPSCs induced by two successive applications of 5-HT did not show significant desensitization (n = 5; Student's paired t test). Cc, plot summarizing the effect of MDL 100907 (300 nm; n = 3). MDL 100907 completely blocked the effect of 5-HT on sEPSCs (P < 0.01; Student's paired t test).