FIG. 4.

Central infusion of 10 μg/day of insulin-like growth factor-1 (IGF-1) increases immature neuron density in the injured hippocampus after controlled cortical impact (CCI). (A) Representative images of doublecortin (DCX; green) immunoreactivity in the ipsilateral hippocampus of vehicle (Veh) and IGF-1–infused sham- and CCI-injured mice at 7 days post-injury. Scale bar represents 50 μm. Granular layer (GL) and Hilus (H). (B) Brain injury resulted in a significant decrease in DCX⁺ cell density in vehicle-treated mice (*p < 0.005, compared to sham + Veh), but not in CCI mice infused with IGF-1. DCX⁺ cell density was significantly greater in IGF-1–treated brain-injured mice than in vehicle-treated counterparts at 7 days after CCI injury (^#p < 0.005, compared to CCI + Veh mice). Immature neuron counts obtained from the ipsilateral granular layer were normalized to the volume of the ipsilateral granular layer to calculate cellular density (1000/mm³). Data are expressed as mean + SEM (n = 4 sham-injured/treatment, n = 10 CCI + Veh, and n = 9 CCI + IGF-1). SEM, standard error of the mean. Color image is available online at www.liebertpub.com/neu