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. 2004 Jan 7;24(1):53–62. doi: 10.1523/JNEUROSCI.4503-03.2004

Figure 5.

Figure 5.

Endocannabinoids mediate depolarization-induced suppression of excitatory synaptic transmission in rat anterior VTA. A, DSE protocol. Under voltage-clamp mode, a 10 sec voltage step (from -70 to +40 mV) was applied to induce transient suppression of EPSCs. Representative traces for each condition from a single experiment are shown. B, Transient suppression of EPSCs induced by depolarization of VTA DA neuron (n = 5; p < 0.0001). The VTA DA neurons were depolarized from -70 to +40 mV for 10 sec under voltage-clamp mode. Each point is the average of the mean EPSCs for the 10 sec period from five different cells. C, DSE increases paired-pulse ratio of AMPA EPSCs (n = 5; p < 0.05). The left-hand graph plots the paired-pulse ratio for each of the experiments in B before (basal) and 5-15 sec after (DSE) the depolarizing step, whereas the right-hand graph plots the averaged paired-pulse ratio in a bar graph form. D, In the presence of either AM281 (500 nm, open triangles) or SR (1 μm, closed circles) the depolarizing voltage pulse caused no changes of EPSCs size (n = 5 for each condition; p < 0.0001). The VTA DA neurons were depolarized from -70 to +40 mV for 10 sec under voltage-clamp mode. Each point is the average of the mean EPSCs for the 10 sec period from five different cells for each condition. E, Time course of the transient suppression of EPSCs induced by depolarization of VTA DA neuron (n = 5; p < 0.0001; open circles) and occlusion of DSE induced by WIN (n = 5; p = 0.0005; closed squares). In the presence of WIN (1 μm; closed squares) the depolarizing voltage pulse caused no changes of EPSCs (n = 5; p = 0.0005). The VTA DA neurons were depolarized from -70 to +40 mV for 10 sec under voltage-clamp mode. Each point is the average of the mean EPSCs for the 10 sec period from five different cells for each condition. F, The magnitude of EPSCs inhibition induced by DSE is plotted as a function of the inhibition induced by AM404 for the five cells in B and Figure 3C, respectively. The data are fit by linear regression with r2 = 0.98 (p < 0.001).