Figure 1. Enriched environment confers beneficial effects to brain and behavior in mice.

(A) Enriched environment (EE) and standard environment (SE) housing conditions. (B) Schematic diagram of the experimental protocol. Mice were tested for anxiety-like behaviors with the elevated plus-maze (EPM) after 3 weeks (immediately before tumor implantation; C and D) or after 5 weeks (2 weeks after Panc02 tumor implantation; D) following housing in EE or SE. (C) Representative travel pathways of an SE and an EE mouse on the EPM. (D) Comparison of time spent in open arm (top) and distance traveled in open arm (bottom) between the SE and EE mice. More time or increased distance in open arm represents lower levels of anxiety-like behaviors. (E) Real-time analysis of brain BDNF mRNA levels in Panc02 tumor-bearing mice. BDNF mRNA expression significantly increased in the hippocampus (top) and hypothalamus (bottom) of the EE mice. (D, E) Data are presented as the mean ± SEM; n = 12 per group. * P < 0.05, ** P < 0.01 versus SE mice.