title: Repeated Short-term (2h×14d) Emotional Stress Induces Lasting Depression-like Behavior in Mice.
abstract: Chronic behavioral stress is a risk factor for depression. To understand chronic stress effects and the mechanism underlying stress-induced emotional changes, various animals model have been developed. We recently reported that mice treated with restraints for 2 h daily for 14 consecutive days (2h-14d or 2h×14d) show lasting depression-like behavior. Restraint provokes emotional stress in the body, but the nature of stress induced by restraints is presumably more complex than emotional stress. So a question remains unsolved whether a similar procedure with "emotional" stress is sufficient to cause depression-like behavior. To address this, we examined whether "emotional" constraints in mice treated for 2h×14d by enforcing them to individually stand on a small stepping platform placed in a water bucket with a quarter full of water, and the stress evoked by this procedure was termed "water-bucket stress". The water-bucket stress activated the hypothalamus-pituitary-adrenal gland (HPA) system in a manner similar to restraint as evidenced by elevation of serum glucocorticoids. After the 2h×14d water-bucket stress, mice showed behavioral changes that were attributed to depression-like behavior, which was stably detected >3 weeks after last water-bucket stress endorsement. Administration of the anti-depressant, imipramine, for 20 days from time after the last emotional constraint completely reversed the stress-induced depression-like behavior. These results suggest that emotional stress evokes for 2h×14d in mice stably induces depression-like behavior in mice, as does the 2h×14d restraint.
authors.affiliation: Laboratory Animal Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-860, Korea.
authors.forename: Kyoung-Shim
authors.initials: KS
authors.lastname: Kim
authors.forename: Hye-Joo
authors.initials: HJ
authors.lastname: Kwon
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Baek
authors.forename: Pyung-Lim
authors.initials: PL
authors.lastname: Han