Modulatory effects of sex steroids hormones in socially isolated female: a study about neuroendocrine profiles related to emotional and cognitive changes
Social isolation; estradiol; progesterone; memory; anxiety; depression
Stress can be defined as a set of physical and psychological mechanisms to coping disturbances that threat the homeostasis. Long-term exposure to stressful events is associated with negatives effect on cognition, emotion and behavior, moreover, these alterations are suggested to be in onset of psychiatric disorders. Glucocorticoids (GCs) are the main hormones involved in stress response. The glucocorticoids receptor (GR) are extensile expressed in different types of tissues in the body, including the central nervous system (CNS), especially in hippocampus, amygdala, and prefrontal cortex. These structures are involved in mood regulation, anxiety and mnemonic processes and are targets of the stress. Although, it remains controversial how stress can impair functionality in these brain areas and how it correlates with disturbances in mood, anxiety and memory impairment. In contrast, oscillations of sex hormones, such as estradiol and progesterone, can profoundly influence the CNS, acting against deleterious effects of stress. In this regard, we used an animal model of chronic stress - social isolation - in female rats with intact estrous cycle to investigate modulatory effect of sex steroid on cognitive and emotional responses. Moreover, we investigated the dissociative effect of estradiol and progesterone, using agonist or antagonist. Our main results demonstrated that: (1) females in diestrus showed depressive-like behaviors and memory deficits when compared to estrus and proestrus phases; (2) depressive-like behaviors and memory deficits induced by social isolation was estrous-cycle dependent; (3) stressed females treated with estradiol (but not progesterone) showed less depressive-like behaviors and memory impairments; (4) tamoxifen (but not mifepristone) induced depressive-like behaviors in proestrus females; (5) There was a anxiolytic effect induced by progesterone. Taken together, these findings suggest that endogenous variations of sex hormones are important to modulate mood, anxiety and mnemonic process in socially isolated females.