Subacute neuroendocrine and behavioral effects of underwater trauma and predator exposure in rats

Traumatic stress physiological response and recovery encompasses a wide range of measurable behavioral and neuroendocrine changes in rats. Acute stress response and return to baseline may vary across differing neuroendocrine signaling molecules and behavioral manifestations, and may also be influenced by extrinsic factors such as the specific stressor presented or phase of the circadian cycle during which responses are evaluated. While rodent models of traumatic stress have been used to evaluate acute and chronic changes in these measures, few longitudinal studies have been done to characterize multiple interrelated neuroendocrine markers across the circadian cycle and compare to acute and lasting behavioral changes. We set out to describe the subacute effects of traumatic stress exposure on exploratory behavior, acoustic startle response, and a panel of neuroendocrine markers across the circadian cycle. Rats were exposed to either underwater trauma (UWT) or predator exposure (PRED). Then repeated behavioral tests (exploratory behavior on the elevated plus maze, acoustic startle) were conducted across 7 days, or in yoked cohorts, blood samples were collected at 10 time points over the next 7 days. Neuroendocrine markers were quantified from serum using LC‐MS or ELISA, analyzed over time, and compared against behavioral responses at several corresponding time points. Preliminary data show differential responses for UWT and PRED across the experimental timeline, and distinct response timelines for the different measures collected. Support or Funding Information Supported by the Military Operational Medicine Research Program, US Army Medical Research and Materiel Command.