Figure 2.

Results of the sucrose consumption test were used to behaviorally phenotype the animals. The graphs display the sucrose consumption of the animals used for the cognitive testing, electrophysiological and histopathological analysis. The repeated testing with the sucrose consumption test enabled us to behaviorally phenotype the animals into stress-resilient and anhedonic rats. Dots represent the individual animals. The anhedonic rats reduced their sucrose intake by more than 30%. A subset of the stressed rats was resistant to the stress and even increased their sucrose intake, similarly to the controls. This group of animals made up the “Stress-resilient” subgroup. Baseline sucrose consumption was defined as the mean sucrose consumption during three sucrose tests conducted before the stress protocol started. There was a significant difference between the groups (p < 0.01) and from Week 5 onwards values of the anhedonic group were significantly different from both the control and stress-resilient groups (Tukey’s HSD test: p < 0.05). Statistics: repeated one-way ANOVA, followed by Dunnets’s comparison test: *p < 0.05 vs. the base(line) value of the same group.