Genetic predisposition to anxiety-related behavior determines coping style, neuroendocrine responses, and neuronal activation during social defeat

Genetic background may influence an individual's susceptibility to, and subsequent coping strategy for, an acute stressor. When exposed to social defeat (SD), rats bred for high (HAB) or low (LAB) trait anxiety, which also differ in depression-like behavior, showed highly divergent passive and active coping behaviors, respectively. HABs spent more time freezing and emitted more ultrasound vocalization calls during SD than LABs, which spent more time rearing and grooming. Although the behavioral data confirmed the prediction that heightened trait anxiety would make rats more prone to experience stress, adrenocorticotropin and corticosterone were secreted to a higher extent in LABs than in HABs. In the latter, Fos expression upon SD was enhanced in the amygdala and hypothalamic areas compared with LABs, whereas it was diminished in prefrontal and brainstem areas.