Figure 3.

β1-integrins in the developing OFC are necessary for dendritic spine stability. Experimental timelines are shown at the top of each row. A, Representative mCherry expression in the OFC of YFP-expressing floxed Itgb1 mice. The contralateral hemisphere outlines the subregions of the OFC on a coronal section from the Mouse Brain Library (Rosen et al., 2000). A neuron coexpressing mCherry and YFP is shown below. B, C, Manual spine counting revealed that early-life Itgb1 knock-down decreased dendritic spine densities (B) and dendritic spine length (C). D, Dendritic spines were reconstructed in 3D by a separate rater. Densities were again diminished in the knock-down group regardless of spine subtype (i.e., main effect of knock-down). Representative dendrites, with their associated 3D reconstructions, are adjacent (n = 9 control, n = 9 knock-down hemispheres). E, F, In contrast to the effects of early-life knock-down, viral vector infusion at P31 did not affect dendritic spine density (E) or length (F). G, 3D reconstruction revealed that knock-down did not affect the densities of non-mushroom-type or mushroom-type spines (n = 7 control, n = 6 knock-down hemispheres). Data are shown as means + SEM, except gray symbols represent individual mice. Individual points in C and F represent individual spines. *p < 0.05, **p < 0.0001 versus control. AI, Agranular insular cortex; LO, lateral orbital cortex; VO, ventral orbital cortex. Scale bar, 2 μm. Dendrites were analyzed by two independent, blinded raters.