Figure 2
LPS produced morphological alterations in newborn granule neurons. GFP- or PSD95:GFP-expressing retroviruses were delivered into the hippocampus, and LPS was administered during different periods, following the experimental design shown in Supplementary Figure S1. Mice were killed at a range of time points to analyze the morphology of 2-, 4- and 8-week-old newborn neurons. (a–j) Representative pictures showing retrovirus-labeled neurons of different ages belonging to the diverse experimental groups. (k) Quantification of total dendritic length. LPS administration at cell birth caused a significant reduction in total dendritic length. These alterations were not reversed (e) 2 or (i) 6 weeks after LPS withdrawal. In contrast, when LPS was administered 6 weeks after cell birth, no decrease in total dendritic length occurred. Ibuprofen reversed the dendritic atrophy produced by LPS administration. (l) Quantification of primary apical dendrite length. LPS significantly and permanently reduced the length of apical primary dendrites. Ibuprofen prevented the appearance of these alterations. (m) Percentage of newborn granule neurons with more than one primary apical dendrite. LPS significantly increased this percentage. The increase was restored 2 or 6 weeks after LPS withdrawal, and abolished by ibuprofen treatment. (n–p) Sholl’s analysis of (n) 2-, (o) 4- and (p) 8-week-old newborn neurons. Sholl's analysis revealed that LPS altered dendritic tree morphology and branching, significantly increasing proximal branching, while a mostly unbranched distal dendritic tree was observed. These alterations were detected regardless of cell age, and also 2 and 6 weeks after LPS withdrawal. Ibuprofen treatment increased distal branching in 4- and 8-week-old neurons. Yellow scale bar, 50 μm. Green triangles, primary apical dendrite. (*, 0.01<P<0.05) (**, 0.001<P<0.01) (***P<0.001) (!, 0.05<P<0.1). GL, granule layer; H, hilus; LPS, lipopolysaccharide; ML, molecular layer; PBS, phosphate-buffered saline.
