Stress-coping behavior during predator odor exposure is associated with differences in decision making

Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are chronic psychiatric disorders that have overlapping symptomology and risk factors, including altered motivation and impulsive behavior. Exposure to a predator odor stressor (2,3,5-Trimethyl-3-Thiazoline (TMT)) produces PTSD-like symptomology in rats. Individual differences in stress-coping behaviors such as freezing and defensive digging during TMT exposure can predict long-term differences in alcohol-related behaviors and altered neurobiology. Here, we evaluated the relationship between stress-coping behavior during TMT exposure and reward-related decision making. In Experiment 1, delay discounting curves in male and female rats were evaluated before and >2 weeks after TMT exposure using an adjusting-amounts delay discounting task. In Experiment 2, using a concurrent choice self-administration procedure, lever responses and preference for alcohol over sucrose were evaluated before and >2 weeks after TMT exposure in females. Additionally, motivation for competing reinforcers was evaluated using progressive ratios. Digging during TMT exposure was correlated with greater post-TMT impulsive choice (Experiment 1), reduced sucrose lever responses both before and after TMT exposure (Experiment 2), and reduced sucrose lever breakpoint after TMT (Experiment 2). High-digging rats showed greater delay discounting than low-digging rats after TMT exposure, though neither were different from controls. Additionally, compared to controls, TMT-exposed females had greater motivation for both alcohol and sucrose self-administration when available concurrently. Overall, these findings suggest that behavior prior to and during a stressful experience can predict individual differences in decision making, which may help future studies identify the neurobiology underlying risk for aberrant reward-related behaviors after a traumatic event.