Brain Sciences · 6 authors, 2 centres
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Rat pups subjected to maternal separation and sibling isolation from postnatal days 2–18 developed a hyperactive behavioral phenotype in adulthood, with sex-dependent changes in brain monoamine levels. Adult rats of both sexes showed increased motor activity and aggressiveness, and decreased anxiety and sociability.
This preclinical study investigated the long-term effects of early life stress in Wistar rats. Pups were separated from their mothers and isolated from siblings for 6 hours daily from postnatal days 2 to 18. Behavioral assessments in adulthood revealed an increase in motor activity and aggressiveness, and a decrease in anxiety and sociability. These behavioral disturbances were accompanied by region-, sex-, and age-dependent changes in brain monoamines (dopamine, serotonin, noradrenaline) and their metabolites. For example, opposite shifts in 5-HT and 5-HIAA were observed in the frontal cortex of males and females. Exposure of adult rats to subsequent physical or emotional stress further altered monoamine levels, indicating sensitivity of the dopaminergic and noradrenergic systems to stress. Key limitations include the measurement of monoamines in large brain regions rather than specific nuclei and the lack of assessment of maternal behavior during the protocol. The findings suggest that early life stress can induce a hyperactive endophenotype and alter neurochemical systems relevant to stress-related disorders, though the causal mechanisms require further study.
