Chronic stress during adolescence as an alternative for the study of resilience in adulthood: The case of fear-enhanced learning after single prolonged stress

COTELLA, EVELIN MARIEL; LEMEN, PAIGE; MARTELLE, SUSAN E.; MOLONEY, RACHEL D.; HOSKINS, OLIVIA; BEDEL, NICHOLAS; HERMAN, JAMES P.

Banff

Workshop; Neurobiology of Stress Workshop; 2018

Chronic stress during adolescence as an alternative for the study of resilience in adulthood: The case of fear-enhanced learning after single prolonged stress. Cotella, E.M.; Lemen P.; Susan Martelle, Rachel Moloney, Olivia Hoskins Bedel N.; Herman J.P.Models of enhanced fear use stress a pontentiator of fear-related responses during aversive learning paradigms. Single-prolonged stress (SPS) is one of the most studied models given its predictive and construct validity as well as its high reproducibility between research groups making it a suitable protocol for the study of posttraumatic stress disorder (PTSD) features.PTSD is a psychiatric condition that can develop after the individual is exposed to traumatic experience. Not everybody that experiences trauma develops the disorder suggesting there must be mechanisms that confer either vulnerability to develop the condition or on the contrary, more resilience to overcome the traumatic experience. Previous results from our lab suggest that, unexpectedly, chronic variable stress (CVS) during adolescence prevents the effect of SPS on auditory-cued fear conditioning. Nevertheless, it is unclear if this effect is solely caused by previous exposure to chronic stress during adolescence or optionally, it is due to previous exposure to similar stressors than the ones used in SPS and therefore the memory of a familiar situation was involved in the effect. To prove this, rats of both sexes were subjected to chronic variable stress (CVS) for a 2-weeks starting at PND44. Typically in CVS, stressors are presented randomly twice daily (cage vibration, cold water swim, warm water swim, cold room, hypoxia, or restraint) and every 2-3 days they had overnight stressors (single housing or overcrowding). In this particular case, we replaced swim instances and restraint by sessions of small cage housing, wet bedding on a tilt cage and stroboscopic light exposure. This way we avoided the animals had a previous experience with the stressors used in SPS. At 85 days of age, a group of the rats was subjected to SPS. For this, they were restrained for 2 hours, followed by 20 minutes of group swim. Immediately after they were allowed to recover for 10 minutes before being exposed to ether vapor until loss of consciousness. The resulting groups were: Control, Adol CVS, SPS and the double-hit group Adol CVS+SPS. After a week, animals? performance in an auditory-cued fear conditioning paradigm was tested. In order to address circuitry involved in the effect, Fos activation was mapped in areas related to the control of stress and fear responses such as medial prefrontal cortex and amygdala.