Background: The rate of depression increases in menopausal women. Possible reasons may involve the effects of ovarian
steroid hormones, including estrogen, on the function of the brain.
Objective: This study aimed to investigate the effects of long-term estrogen deprivation on depressive-like behavior and
noradrenergic neurotransmitters in the brain areas involved in the regulation of emotional behavior.
Material and Method: Adult female Wistar rats were ovariectomized and randomly assigned into 2 groups, ovariectomized (Ovx) rats and Ovx rats treated with estrogen (E2) (10 μg/kg BW, subcutaneously into the dorsal region of the neck, once daily). Four weeks after ovariectomy, the rats were tested in open field and forced swim tests. After the behavioral tests, their brains were removed for measurement of norepinephrine (NE) and 3-methoxy-4-hydroyphenylglycol (MHPG) levels.
Results: Four weeks after ovariectomy, the Ovx rats showed longer immobility time in the forced swim test than the E2 rats.
NE levels in the hippocampus and the adrenal gland weights tend to be increased after ovariectomy.
Conclusion: Long-term estrogen deprivation for four weeks promoted depressive-like behavior in female Wistar rats and
also altered NE levels in the hippocampus. This finding indicated that long-term estrogen deprivation alters noradrenergic
neurotransmission and the HPA axis.

Keywords: Depression, Estrogen, Forced swim test, Ovariectomized-rat