Figure 2.
Properties of DSE at synapses onto cerebellar interneurons. PFs were activated with paired pulses (50 ms interpulse interval) 17 s before and 3 s after the postsynaptic cell was depolarized to 0 mV for 2 s. The CB1R agonist WIN 55,212-2 (2 μm) was bath applied, followed by the CB1R antagonist AM251 (5 μm). Experiments were performed in 4 mm calcium. Effects on EPSC amplitude are shown in A and B, and changes in paired-pulse ratio are shown in C and D. A, A representative experiment is shown for PF to SC synapses; the average response before (black) and 3 s after (gray) depolarization is plotted for each condition (top), and the normalized EPSC amplitude is plotted as a function of time (bottom). B, Experiments as in A are summarized to compare the effects of depolarizing the postsynaptic cell in control conditions with the effects of WIN 55,212-2 on the magnitude of the EPSC for the various types of PF synapses. C, Representative average responses are shown for PF to SC synapses before depolarization (black traces) and 3 s after depolarization (gray traces). Responses are normalized to the first EPSC to allow comparison of the extent of facilitation before and after depolarization (the amplitudes of EPSC1 before and after depolarization were 350 and 120 pA, respectively). D, Summary of the change of facilitation induced by depolarization, with the average paired-pulse ratio (PPR = EPSC2/EPSC1) in control conditions before depolarization (black bars), after depolarization in control conditions (white bars), and in the presence of WIN 55,212-2 (gray bars). WIN, WIN 55,212-2; norm., normalized.
