Figure 3. The Long-Lasting Hyperpolarization Is Absent in CB₂R-Deficient Mice.

(A–C) AP trains (rectangle) induce a long-lasting hyperpolarization in CB₁R^−/− CA3 PCs (A), but not in CA3 PCs of CB₂R^−/− (B) and Syn-CB₂R^−/− mice (C). Left: exemplary pp recordings of KO CA3 PCs are shown. Right: summary time course shows the average ΔV_m of CA3 PCs recorded from CB₁R^−/−: n(N) = 8(6), CB₂R^−/−: n(N) = 15(7), and Syn- CB₂R^−/−: n(N) = 8(5). The x axis is discontinued for the duration of the AP train.

(D) Same is shown as for (A)–(C) except for WT littermate controls of CB₂R^−/− and Syn-CB₂R^−/− mice: n(N) = 4(3)/4(2).

(E) The ΔV_m of each recorded cell (circles) and the median and 25^th and 75^th percentiles of the average ΔV_m (min 9–10) are shown for CA3 PCs recorded in CB₁R^−/− (−4.3, −5.8, and −2.6 mV), (Syn-)CB₂R^+/+ littermates (−4.7, −5.8 to −3.5 mV), CB₂R^−/− (0.39, −0.57 to 1.4 mV), and Syn- CB₂R^−/− (0.53, 0.086 to 1.1 mV). Kruskal-Wallis with Dunn’s post test, p < 0.0001 for [WT and CB₁R^−/−] versus [CB₂R^−/− and Syn-CB₂R^−/−]. The average ΔV_m of WT versus CB₁R^−/− and CB₂R^−/− versus Syn-CB₂R^−/− did not differ significantly.

(F) Percentage of reactive cells are shown.