Figure 7.

Effects of diet and testosterone on behavioral performance in the Barnes maze and on neurogenesis in young, middle-aged, and aged brown Norway rats. A-C) Average latency to located the escape box over the course of 4 days of training in A) young, B) middle-aged, and C) aged male brown Norway rats maintained on control and high fat diet. D-E) Average latency to locate the escape box in testosterone-treated D) middle-aged and E) aged rats fed control or high fat diet. F) The number and G) percentage of correct hole visits during the Barnes maze probe trial, 48 h after the last training trial. H) The number of errors made during the probe trial and I) the distance traveled to locate the escape box for the first time during the probe trial. J) Neurogenesis as measured by the density of double cortin-expressing cells in the dentate gyrus. Animals not treated with testosterone are shown in white (Experiment 1), and animals treated with testosterone in gray (Experiment 2); control diets are solid white or gray bars, high fat diets are striped bars. a p < 0.05 relative to young rats in same diet condition. b p < 0.05 relative to middle-aged animal in same diet condition. # p < 0.05 for main effect of diet that does not reach statistical significance in post hoc tests.