Subchronic stress-induced depressive behavior in ovariectomized mice.
OBJECTIVE
Mood disorders including depression are more common in women than men, particularly in times of lower estradiol levels. In this study, we investigated the effect of estrogen on emotional behavior in mice in a stress environment.


METHODS
Female mice were divided into four groups: two groups were ovariectomized (OVX) and two were sham-operated. One group each of OVX and sham mice was kept in a normal environment and the other groups were assigned to a daily stress (1 h/day) for 7 days from 5 days after operation. On the 14th day after operation, subjects were measured to assess behavioral specificity, locomotor activity, elevated plus-maze (EPM) behavior, passive avoidance (PA) behavior and forced swimming behavior.


RESULTS
The OVX plus stress (OVX+S) group showed a significant prolongation of immobility compared with the other groups. In all the groups there were no changes in locomotor activity, EPM behavior or PA behavior. We further examined the effect of estrogen against depressive behavior in the OVX+S group. The vehicle or 17beta-estradiol (E2) was administered s.c. to OVX+S mice for 4 days beginning on post-operative day 11. Subchronic E2 treatment decreased the stress response and improved depressive behavior relative to the vehicle group.


CONCLUSIONS
These data have important implications regarding the prevention of depression in postmenopausal women undergoing estrogen therapy.
Nakagawasai
Osamu
O
Department of Pharmacology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan. osamun@tohoku-pharm.ac.jp
Oba
Akira
A
Sato
Atsushi
A
Arai
Yuichiro
Y
Mitazaki
Satoru
S
Onogi
Hiroshi
H
Wakui
Kenji
K
Niijima
Fukie
F
Tan-No
Koichi
K
Tadano
Takeshi
T
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D002908:Chronic Disease; D003863:Depression / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology / Q000517:prevention & control; D004195:Disease Models, Animal; D004958:Estradiol / Q000378:metabolism* / Q000627:therapeutic use; D005260:Female; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000502:physiology*; D010052:Ovariectomy; D013315:Stress, Psychological / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D013550:Swimming / Q000502:physiology
D004958:Estradiol