Effects of chronic psychosocial stress on the brain oxytocin (OXT) and neuropeptide S (NPS) systems, and potential stress-protective actions of chronic OXT and NPS administration

The neuropeptide oxytocin (OXT) and neuropeptide S (NPS) have established anxiolytic (OXT, NPS) and antidepressive (OXT) effects, and modulate the acute neuroendocrine stress response. However, effects of chronic psychosocial stress on the adult brain OXT and NPS systems are largely unknown. Similarly, although chronic psychosocial stress results in increased anxiety levels, among others, effects of OXT or NPS administration on behavioural or neuroendocrine parameters in the context of chronic stress have never been assessed. Here, we aim to study the effects of an established chronic psychosocial stress paradigm, i.e. chronic subordinate colony housing (CSC) in mice, on the brain OXT and NPS systems with respect to neuronal expression of the neuropeptides and their receptors, as well as the responsiveness of the OXT system to a novel, acute stressor monitoring central (microdialysis in PVN, amygdala) and peripheral (jugular vein catheter) release patterns comparing single-housed control (SHC) and CSC mice. Moreover, we will test for potential anti-stress effects of chronic OXT and NPS administration via osmotic minipumps during and following CSC exposure, respectively, with respect to CSC-induced alterations in anxiety and selected physiological (body, adrenal and thymus weight, HPA axis (re)activity) and immunological (signs of colonic inflammation) parameters.