Early adversities can shape adult behavior, and the early developmental period is an important temporal window for the maturation of brain structures. Potential different phenotypes resulting from environmental modifications during development can eventually impact susceptibility to psychiatric disorders and contribute to the emergence of eating disorders, substance abuse, as well as alter cognitive processes and memory formation. Maternal separation (MS) is a model of early stress that leads to long-lasting changes in the responsiveness of the hypothalamic-pituitary-adrenal axis, as well as behavioral, cognitive, and neurochemical alterations. Studies with rodents demonstrate sex-specific differences in the effects of MS on adult behavior. One hypothesis related to the long-term effects of early stress is known as the "second hit" or cumulative stress hypothesis, which postulates that through the interaction between specific genes and the environment, stressful experiences during the early developmental period can program how an individual faces a second stressor later in life, potentially magnifying the consequences of this second stressor. The aim of this study was to investigate the effects of early stress, through MS (postnatal day 1-10, 3h per day), on the memory of an aversive event (contextual fear conditioning task, 3 footshocks x 1s x 0.5mA) after a second hit (a week of seven different stressors) evaluating the acquisition (24h), extinction (2 sessions of 20min each, test 24h later) and spontaneous recovery of aversive memory (14 days after last extinction session) in adult Wistar rats, both males and females. The results will be presented during the FENS Forum 2024.