Diverse modulatory effects of sex steroids on depressive-like behavior in socially stressed female rats.

Abstract

The role of sex steroids in mammals extends beyond the conventional influence on the reproductive system. Sex hormones have been shown to modulate Public Significance StatementHormones connected to the hypothalamic-pituitary-adrenal and the hypothalamicpituitary-gonadal axes can interact and influence affective-like behaviors. However, the neurological basis of the role of these hormones in depressive illnesses caused by chronic stress is still debated, in part due to a lack of studies that include females in their experimental protocols. This study suggests that endogenous fluctuations in estrogen levels across the estrous cycle affect depressive-like behaviors triggered by social isolation. Estradiol had a beneficial effect on depressive-like behaviors, which was counteracted by prior exogenous administration of the antagonist tamoxifen. Furthermore, neither progesterone nor mifepristone caused significant changes.