Fig. 2

Effects of pharmacological deletion of microglia on CF synapse elimination. a–f Double immunolabeling for Iba1 (red) and calbindin (green) in liposomal clodronate (a–c) or control liposome (d–f) injected mice at P8. Asterisks in a and d indicate the injection sites of the liposomes in lobules VI–VII in the vermis. Regions surrounded by solid and dotted lines are magnified in b and e, and c and f, respectively. Iba1-labeled microglial cell numbers are significantly reduced in the clodronate-injected lobules VI–VII (b), but not in the neighboring lobules IV–V (c). g, h (left) Representative traces of CF-EPSCs recorded in mice treated with control (upper) or clodronate (lower) liposomes at P6 (g) or P11 (h). Electrophysiological recordings were conducted from PCs in the liposome-injected lobules at P21–P31. The holding potential (Vh) is −10 mV. Scale bars, 1 nA (g), 0.5 nA (h) and 10 ms. (right) Frequency distribution histograms showing the number of discrete CF-EPSC steps. Data were sampled from five control and five clodronate-treated mice in each of g and h. CF synapse elimination was significantly impaired in mice treated with clodronate at P6 (g, p < 0.001, Mann–Whitney U test), but not at P11 (h, p = 0.290). Scale bars, 300 μm (a, d) and 50 μm (b, c, e, f). ***p < 0.001; n.s., p > 0.05