Figure 1.
Effect of 5-HT4 receptors on synaptic and intrinsic properties of subicular BS neurons.
A: Voltage responses of a burst-spiking subicular neuron upon depolarizing and hyperpolarizing current pulses. B: Voltage responses of a regular-spiking subicular neuron to depolarizing and hyperpolarizing current pulse. C: The 5-HT4 receptor agonist RS 67333 does not modulate EPSP responses during 30 minutes of wash-in. D: The 5-HT4 receptor antagonist RS 39604 does not alter EPSP responses during 30 minutes of wash-in. Scale bars: 20 mV and 50 ms (B); 2 mV and 20 ms (C1, D1).
Table 1.
Synaptic and membrane properties of BS-cells in the subiculum before and after application of 5-HT4 receptor ligands.
Figure 2.
Effect of 5-HT4 receptors on LTP.
A1: HFS induces LTP under control conditions. A2: The 5-HT4 receptor agonist RS 67333 does not alter LTP. A3: The 5-HT4 receptor antagonists RS 39604 does not modulate LTP. B1: stHFS induces PTP but not LTP under control conditions. B2: The 5-HT4 receptor agonist RS 67333 failed to prime LTP after stHFS. B3: The 5-HT4 receptor antagonist RS 39604 failed to facilitate the induction of LTP after stHFS. Scale bars: 2 mV and 20 ms.
Figure 3.
A1: LFS induces LTD under control conditions. A2: Activation of 5-HT4-receptors significantly facilitates LTD. A3/4: Blockade of 5-HT4-receptors through RS 39604 or GR 113808 prevented LTD. B: Summary of changes in synaptic strength illustrated in A1-4. The antagonist GR 13808 is not included in the ANOVA. C: Averaged time courses of normalized EPSP responses during LFS. Control: white circles, RS 67333: black circles, RS 39604: gray circles, GR 113808: dark gray squares. D1: The PKA inhibitor H 89 prevented LTD under control conditions. D2: H 89 prevented LTD even in the presence of the 5-HT4 receptor agonist RS 67333. E: A 5-HT4 receptor agonist failed to modulate NMDA receptor mediated EPSPs during 30 minutes wash-in. Scale bars: 2 mV and 20 ms (A,D), 1 mV and 20 ms (E).