Effects of MPEP or CPCCOEt on the morphology of dendritic spines in cultured Purkinje cells. Drugs were applied to the cultures from 6 to 9 DIV. Note that the dendritic branches of control Purkinje cells at 9 DIV are covered by headed spines (A), whereas dendrites of Purkinje cells treated with MPEP show longer protrusions devoid of heads (B). Kruskal–Wallis one-way ANOVA on ranks revealed a statistically significant difference between groups (*p < 0.05 by Dunn's method). C, Control (CTR; n = 291),MPEP (n = 220),CPCCOEt (n = 287); boxescontain 50% of values; the line dividing thebox represents the median (control = 1.5 μm; MPEP = 2.3 μm; CPCCOEt = 1.7 μm); bottomand top lines represent the 25th and 75th percentile, respectively. The number of spines was obtained from 10–15 cells per group from a single experiment performed in triplicate. Identical data were observed in three experiments performed on different culture preparations. Scale bar, 12 μm.