Doublecortin (DCX) immunostaining.

(A) Microphotographs corresponding to the DCX immunohistochemistry in the dentate gyrus. (B) Tracing of the dendritic tree of the DCX-positive neurons shown in panel A. Scale bar corresponds to 50 µm. (C) Quantification of the dendritic length of E-F-type DCX-positive neurons. Shorter dendritic trees were found in DIAB-SC mice (** p<0.01 vs. CTL-SC) and environmental enrichment prevented this reduction in the diabetic group (# p<0.05 DIAB-SC vs. DIAB-EE) and, also, in control mice (** p<0.05 CTL-SC vs. CTL-EE). (D) Quantification of the number of DCX-positive cells in the subgranular zone and granular cell layer. No differences were found between groups in the number of total DCX-positive cells and of A-D-type cells. We found a main effect of the ‘glycemic condition’ decreasing the number of E-F-type DCX-positive cells (p<0.01). (E) and (F) Percentage of DCX-positive cells showing an A–D (E panel, less mature) and an E–F phenotype (F panel, more mature; see the Materials and methods section for further details). Diabetic animals showed an increased percentage of A–D cells and a concomitant reduction in the E–F percentage (* p<0.05 DIAB-SC vs. CTL-SC and ** p<0.01 DIAB-EE vs. CTL-EE).