Figure 3: Treatment with Mino decreases filopodia formation.

(a) Time-lapse in vivo images of microglia–dendrite interaction in Mino-treated mice, illustrating contact that was not followed by filopodia formation. Yellow arrowhead indicates the contact point. Scale bar, 5 μm. (b) Filopodia formation rate at microglia contact points (contact) was significantly decreased in Mino-treated mice, as compared with control saline-injected mice, and was the same as observed at dendritic regions 10 or 20 μm adjacent to the contact point, or across the the whole dendrite (excluding the contact region) (one-way ANOVA, post-hoc Tukey’s test, error bars are mean ±s.e.m.; exact P-values are P=0.016 (Mino, Saline), P=0.96147 (Mino contact, Mino 10 μm), P=0.84726 (Mino contact, Mino 20 μm), P=0.57751 (Mino contact, Mino no contact); Saline n=13, Mino n=10 animals). (c) Mino did not significantly affect the microglia–dendrite contact frequency (unpaired t-test, error bars are mean ±s.e.m.; exact P-value is P=0.86; Saline n=13, Mino n=10 animals). (d) The spine density in basal dendrites of L2/3 pyramidal neurons from Mino (right)-injected mice tended to be smaller than in saline-injected mice. Left panel, sample image, yellow arrowheads indicate spines. Scale bar, 5 μm. Right panel, mean spine densities (unpaired t-test, error bars are mean ±s.e.m.; exact - value is P=0.054; Saline n=9, Mino n=10 mice). (e) Iba1 mRNA levels were higher in the cortex of P8 saline-injected mouse compared with age-matched Mino-injected mice (unpaired t-test, error bars are mean ±s.e.; exact P-value is P=0.019; Saline n=4, Mino n=4 animals). (f) Cortical Iba1 mRNA levels were significantly decreased over age, from P9 through to P14 or P30 mice (one-way ANOVA, post-hoc Bonfferoni test, error bars are mean ±s.e.; exact P-values are P=0.032(P9, P14), P=0.037(P9, P30); P9 n=3, P14 n=3, P30 n=3 animals).