Ketamine improved depressive‐like behaviors via hippocampal glucocorticoid receptor in chronic stress induced‐ susceptible mice

Mice that showed a rise in plasma corticosterone two hours after a single social defeat stress went on to develop depressive-like behaviors after ten days of repeated defeat. Resilient mice did not show this early corticosterone increase. Susceptible mice maintained elevated corticosterone even 48 hours after the last stress. Giving corticosterone in drinking water made mice susceptible. The glucocorticoid receptor antagonist mifepristone reduced susceptibility. A single dose of ketamine improved depressive-like behaviors, lowered corticosterone, and restored glucocorticoid receptor expression and nuclear translocation in the hippocampus. Abnormal corticosterone after stress may predict susceptibility to depression, and ketamine may work by normalizing HPA axis response.

Study at a glance

Abstract

HighlightsSusceptible mice showed depressive‐like behaviors upon chronic social defeat stress.Plasma corticosterone concentration might predict susceptibility to chronic stress.Abnormal glucocorticoid receptor expression was associated with susceptibility.Ketamine exerted antidepressant effect via normalizing HPA axis response. &NA; Chronic stress is an important factor for depression. Most individuals recover from stress, while some develop into depression. The pathogenesis of resilience or susceptibility remains unclear. Stress activates the hypothalamic‐pituitary‐adrenal (HPA) axis and releases stress hormones to regulate individual response to stress. Hence, we assessed the effects of chronic social defeat stress (CSDS) on susceptible behaviors, plasma corticosterone (CORT) concentration, glucocorticoid receptor (GR) expressions in hippocampus and medial prefrontal cortex (mPFC). Mice that plasma CORT concentration is increased 2 h after single social defeat stress developed into susceptible mice after 10 d social defeat stress. The plasma CORT concentration was still higher than that of resilient mice 48 h after the last defeat stress. Mice administered CORT via drinking water showed susceptibility. Mifepristone, a GR antagonist improved susceptibility to chronic stress. Single dose ketamine treatment improved depressive‐like behaviors, decreased plasma CORT concentration, rescued GR expression and nuclear translocation in the hippocampus of susceptible mice. These results suggested that abnormal CORT concentration after stress may predict susceptibility to depression in clinic. Ketamine may exert the antidepressant effect via normalizing HPA axis response and have significance in the clinic.