Early life stress-induced increases in adult fear learning are maintained overtime in male and female rats

Globally, many individuals experience stress-related disorders, such as posttraumatic stress disorder (PTSD), at some point during their lives. Early adverse experiences are associated with increased vulnerability to psychiatric and somatic health conditions in adulthood. Rodent models are commonly used to examine the neurobiological mechanisms underlying stress-related disorders. We have previously demonstrated that acute ELS (aELS) exposure leads to fear memory incubation following adult fear conditioning in mice. Importantly, mice that were not exposed to aELS did not demonstrate this incubation. The present study aimed to replicate this effect in rats while also harvesting tissue at both early and late retention timepoints to address potential mechanisms underlying maladaptive fear incubation. Rats were exposed to either 0 or 15 footshocks on postnatal day 17. In adulthood, all rats received 1-footshock fear conditioning in a novel context and were tested for freezing in that context either 1 day or 30 days later. Ninety minutes following the test session, rats were intracardially perfused with phosphate buffered saline followed by 4% paraformaldehyde. Brains were extracted and stored for subsequent analysis of c-Fos immunoreactivity. The behavioral data demonstrate robust stress-enhanced fear learning (SEFL) in both males and females at the 1-day and 30-day retention intervals, with no evidence of fear memory incubation. Thus, we demonstrate maintenance of SEFL over time in rats, which differs from the pattern we saw previously in mice. Ongoing c-Fos analyses are targeting to the dorsal hippocampus and medial prefrontal cortex, given their established roles in recent versus remote memory expression, respectively. 

• Minshall, B. L., Peguero, A. Z., Scheive, K. M., Wasylyshyn, C. F., Claflin, D. I., Quinn, J. J. (2025).  Acute early life stress alters threat processing in adult rats. Behavioral Neuroscience, 139: 20-29. doi: 10.1037/bne0000608

• Minshall, B. L., Skipper, R. A., Riddle, C. A., Wasylyshyn, C. F., Claflin, D. I., & Quinn, J. J. (2024). Sex differences in acute early life stress-enhanced fear learning in adult rats. Developmental Psychobiology, 66(5): e22511. doi: 10.1002/dev.22511

• Reichert, A. N., Riddle, C. A., & Quinn, J. J. (2025). Social buffering of acute early life stress sex-dependently ameliorates maladaptive fear incubation in adulthood. Developmental Psychobiology, 67(5): e70082. doi: 10.1002/dev.70082 

• Sneddon, E. A., Riddle, C. A., Schuh, K. M., Quinn, J. J., & Radke, A. K. (2020). Selective enhancement of fear learning and resistance to extinction in a mouse model of acute early life trauma. Learning & Memory, 28(1):12-16. doi: 10.1101/lm.052373.120 

This research was approved by the Miami University IACUC Protocol # 1082_2026_Feb