Figure 2.
CB1 receptor activation is not responsible for D2 receptor-induced acute depression of IPSCs. A, Bath application of cocaine (10 μm) produced reversible depression of IPSCs (n = 5). In the presence of CB1 receptor antagonist AM 251 (2 μm), cocaine produced similar depression of IPSCs (n = 5). B, AM 251 had no significant effect on D2 receptor agonist quinpirole-induced depression of IPSCs (n = 5). C, Bath application of quinpirole induced similar depression of IPSCs in dopamine neurons in slices from CB1+/+ mice (n = 7) and CB1−/− mice (n = 5). D, Blocking postsynaptic K+ conductance with either Cs+-based internal solution (n = 6) or K+-based internal solution containing GDP-β-S (2 mm, n = 7) had no significant effect on quinpirole-induced depression of IPSCs. E, The effect of bath application of quinpirole (10 μm) on mIPSCs in dopamine neurons. F, Quinpirole decreased the mean frequency of mIPSCs (n = 6; p < 0.05). G, Quinpirole did not significantly shift the amplitude distribution of mIPSCs as shown by cumulative probability plots.