Early life stress exposure: a pattern of adaptation or vulnerability to the development of stress-related psychopathologies?

Stressful experiences in childhood are among the most important risk factors for the development of a whole spectrum of mental and physical illnesses in adulthood. The plasticity of the brain is particularly pronounced in the early stages of life; therefore, aversive conditions can have conspicuous and long-lasting effects during early development. Here we assessed whether prenatal stress (PNS) exposure could confer susceptibility or resilience to the development of psychopathological conditions in adolescence following a second stressful experience in adolescence (single prolonged stress, SPS) and whether these alterations were sex-specific in rats. Behavioral alterations in the emotional and cognitive domines were examined in adolescent rats of both sexes exposed to PNS (at gestational day 14) or SPS (at postnatal day 23) or both in a battery of tests. Our results in males showed behavioral alterations in the Open field following exposure to PNS and alterations of social play behavior in the PNS or SPS alone groups, as compared to controls. Furthermore, exposure to both stressors reduced auditory conditioned fear acquisition and recall in males only. Exposure to PNS or SPS increased pre-pulse inhibition, while it did not alter the total amplitude of a startle response, in males. Overall females remained largely unaffected by the adverse exposures only showing increased grooming behavior in the Open field task following exposure to the PNS+SPS relative to controls, possibly indicating increased anxiety-like behavior. Taken together, these results suggest that early life stress alters emotional and cognitive behavior in adolescence and lay the foundations for more mechanistic investigations to allow the identification of new prophylactic and therapeutic targets for the treatment of psychopathologies at a young age.