Hypothalamic-pituitary-adrenal axis responsivity to an acute novel stress in female rats subjected to the chronic mild stress paradigm.

The chronic mild stress (CMS) paradigm is the most frequently investigated animal model for major depression. The hypothalamic-pituitary-adrenal (HPA) axis participates in the generation of depressive symptomatology. We examined whether the depression-like state induced by CMS is associated with immediate changes in HPA axis activation in response to a novel acute stress and whether this response could be modified by hormonal status.

Estrogen receptors ERα and ERβ participation in hypothalamus-pituitary-adrenal axis activation by hemorrhagic stress.

The sympato-adrenal-system and hypothalamus-pituitary-adrenal (HPA) axis are anatomically and functionally connected with participation of several brain areas that express estrogen receptors (ERα and ERβ). We assessed the neuronal activity of these areas for FOS expression and the action of PPT (ERα agonist) or DPN (ERβ agonist) in HPA axis activity during hemorrhagic stress. Ovariectomized Wistar rats treated with vehicle (DMSO) or ER agonists were catheterized for blood collection.