Figure 2.

New neurons born into a chronic inflammatory environment differentiate into mature dentate granule cells. A, GFP⁺ cell located in the GCL with dendrite (arrow) reaching well into the ML 3 d after RV-GFP labeling. B, GFP⁺ cell with branched dendrites and an axon (arrow) in the hilus 10 d after RV-GFP labeling. Highly branched dendritic trees (C) with spines (inset, arrowheads) on GFP⁺ cells 16 d after RV-GFP labeling. Distribution of new GFP⁺ neurons in the GCL of vehicle- (D) or LPS-injected (E) animals 7 weeks after RV-GFP labeling. F, Relative location of GFP⁺ cells in inner, middle, or outer GCL (iGCL, mGCL, and oGCL, respectively), ML, or hilus. G, Polarity of the GFP⁺ cell soma, where 90° is perpendicular to GCL direction. 0, 45, and 90° comprise 0–22, 22.5–67, and 67.5–90°, respectively. H, Cumulative number of dendritic branching points at increasing distances from the GFP⁺ cell body. Microscopical analyses in F–H were performed 8 weeks after LPS or vehicle injection. No differences between LPS- and vehicle-treated animals were observed. Error bars indicate SEM. Student's unpaired t test, p > 0.05. GFP⁺ neurons visualized for patch-clamp analysis after vehicle (I) and LPS (J) injection. Coexpression of GFP (green) and biocytin (red) that had diffused from the patch pipette into the recorded cell (yellow; arrow) with neighboring, nonrecorded GFP⁺/biocytin⁻ cells (arrowheads). Cells in I and J are from same animals as in D and E. Action potentials and current–voltage relationship plots of new and mature neurons from vehicle-treated (K) and LPS-treated (L) animals (recordings at 7–8 weeks after RV-GFP injection). Current injections of 500 ms were delivered in 15 pA increments. Traces are shown with 100, 200, and 300 pA injection. LPS, n = 130 cells; vehicle, n = 332 cells (F–H). Scale bars: (in E) A, B, 10 μm; (in E) C, 25 μm; (in E) C, inset, 5 μm; (in E) D, E, 215 μm; (in J) I, J, 30 μm. Calibration: K, L, 100 ms, 20 mV.