CommentaryDefeating the fear: New insights into the neurobiology of stress susceptibility

The psychopathological impact of emotional stress on a specific individual varies markedly: while most escape the development of post-traumatic stress disorder and/or major depression, a select group of individuals demonstrate a vulnerability to succumb to these conditions. The past decade has witnessed an explosion in animal research into the underlying neurobiological mechanisms that govern both vulnerability and resilience to such stressors. In the May 2014 issue, Chou and colleagues employ the mouse social defeat model of chronic stress to demonstrate that defeated susceptible mice display an exaggerated conditioned fear response associated with more pronounced autonomic changes. These physiological alterations were found to be mediated via local increases in the levels of brain derived neurotrophic factor (BDNF) within the basolateral amygdala and could be inhibited by the systemic administration of a beta adrenergic antagonist. This mini-review critically examines this manuscript's new mechanistic insights in light of previous results employing similar approaches. The strengths and limitations of the social defeat model, as well as the relevance of these findings to neurologic illness are discussed briefly.