Teens, stress and hormones: Impact of stress during adolescence on behavior and brain activation of male and female rats

Adolescence is a period of major physical, hormonal and psychological change. It is also characterized by a significant increase in the incidence of psychopathologies and this increase is gender-specific. Likewise, stress during adolescence is associated with the development of psychiatric disorders later in life. Here, we study the immediate impact of psychogenic stress before and during puberty (postnatal days 28-42) on behavior (novelty seeking, risk taking, anxiety and depression) and hypothalamus-pituitary-adrenocortical (HPA) axis activation and brain metabolism during late adolescence (postnatal days 45-51). Peri-pubertal stress: a) decreased anxiety-like behavior and increased risk taking and novelty seeking behaviors during late adolescence; b) did not affect depressive-like behavior; c) decreased fear memories (freezing in response to a tone associated with electrical shock) only in females; d) did not affect brain activation on basal conditions (home cage) but increase activation of hippocampus, basal amygdala, cingulated and motor cortices when the animals underwent recall of a tone associated to electrical shock; and e) did not affect acute HPA response to stress (blood corticosterone and glucose). Interestingly, when controlling for the basal anxiety of the mothers, animals exposed to peri-pubertal stress showed a significant decrease in corticosterone levels right after an acute stressor. The results from this study suggest that exposure to mild stressors during the peri-pubertal period induces a broad spectrum of behavioral and brain activation changes in late adolescence, which seems to exacerbate the independence-building behaviors naturally happening during this transitional period (increase in curiosity, sensation-seeking and risk taking behaviors).