Figure 3

Neurite outgrowth following incubation with astrocyte conditioned medium (CM). CM was generated from TR APOE primary astrocytic cultures and collected after 72 hours. Primary wt neurons were treated with astrocyte CM (50% of total volume) or 100% Neurobasal medium (control). For RAP treatment, neurons were preincubated with 200 nM RAP for 2 hrs prior to the addition of CM. After 48 hours, neurons were immunostained with anti-MAP2 antibody (1:500) and examined with a confocal microscope using LaserSharp software (BioRad). Five or more MAP2-stained neurons were randomly selected and dendrite length (A) and branch number (B) determined by Neurolucida. Data are expressed as mean length or branch number ± SEM (n = 5). One-way ANOVA for neurite length (A) had P < 0.0001 and Bonferroni-corrected repeated pair analysis had *P < 0.001 for TR APOE2 vs. control but P > 0.05 for TR APOE4 or TR APOE2+RAP vs. control. For branch number (B), one-way ANOVA had P < 0.05 and Bonferroni-corrected repeated pair analysis had ^#P < 0.01 for TR APOE2 vs. control, P > 0.05 for TR APOE4 or TR APOE2+RAP vs. control, and ^P < 0.05 for TR APOE2 vs. TR APOE2+RAP.