Post-traumatic stress disorder (PTSD) affects nearly 8 million people and anxiety disorders affect nearly 40 million people in the United States, making them the most common subtype of mental health diagnoses. Early life stress (ELS) exposure yields substantial vulnerability to developing PTSD and anxiety later in life. Determining the impact of ELS requires a closer examination of the type of ELS experienced. Chronic ELS (cELS) is of interest since prolonged exposure to stress may yield greater, more potent effects in adulthood. Specifically, this experiment addresses how chronic early life stress later affects fear responses and anxiety-like behavior in adulthood. Rats received no ELS or cELS, as a limited bedding and nesting model, during infancy. In adulthood, half of the rats in each condition received mild fear conditioning. We hypothesized that animals who received cELS would exhibit stress-enhanced fear learning (SEFL), a PTSD-like phenotype, with or without adult fear conditioning. Animals who received cELS and no adult fear conditioning were predicted to exhibit an anxiety-like phenotype, measured as time spent by perimeter walls (thigmotaxis), in the open field test. The addition of adult fear conditioning was predicted to heighten the anxiety-like phenotype. It was found that animals who received cELS did not exhibit SEFL in adulthood. Additionally, distance traveled appears to be a more sensitive measure for anxiety-like behavior. Future studies should assess whether acute ELS results in differences in the open field and whether animals that receive control bedding and aELS show SEFL and/or differences in the open field.
Authors: Sophia W. H. Bick, Nazif B. Vardar, Carson A. Powell, Lauren A. Roos, Barrett W. Croskey, Brianna Minshall, & Jennifer J. Quinn, PhD
Advisor(s): Jennifer Quinn, Department of Psychology
Brianna Minshall, Department of Psychology
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