FIGURE 1.

Inhibition of Cdk5 enhanced mGluR‐LTD in CA1 neurons from wild‐type mice and prevented 5‐HT7 receptor‐mediated effect on mGluR‐LTD. AMPA receptor‐mediated excitatory post‐synaptic currents (EPSCs) were recorded in the presence of D‐AP5 (50 µM) and bicuculline (5 µM) under whole‐cell patch clamp in the CA3‐CA1 synapse in hippocampal slices from wild‐type mice. (a) Bath application of the group I mGluR agonist DHPG (100 µM, 5 min) induced a long‐term depression (mGluR‐LTD) of EPSC amplitude (white dots, n = 11). When the Cdk5 inhibitor roscovitine (1.6 µM) was added to intracellular medium, DHPG‐induced mGluR‐LTD was enhanced (light grey dots, n = 7) with respect to control. (b) When DHPG application was followed by application of the 5‐HT7 receptor agonist LP‐211 (10 nM, 5 min), mGluR‐LTD was completely reversed (dark grey dots, n = 6). In the presence of intracellular roscovitine (1.6 µM), application of LP‐211 did not modify the amount of mGluR‐LTD (black dots, n = 6). (c) The bar graph shows that the amount of mGluR‐LTD measured 40 min after DHPG application (mean EPSC amplitude in all tested neurons, expressed as % of baseline EPSC amplitude; EPSC values of single neurons are displayed for each bar) in the four different experimental conditions (control; roscovitine; LP‐211; LP‐211 + roscovitine) was significantly different (p = 0.0006 by one‐way ANOVA followed by Tukey's multiple comparisons test). *p < 0.05; ***p < 0.001