Adolescent social profiles predict adult social behaviour, monoamine brain content and regional gene expression

The study of inter-individual variability in animal behaviors during cognitive processes is crucial to better grasp the emergence of personality traits in healthy animals. Social experiences occurring at adolescence can affect the expression of the behavioural variability as it is a critical period of brain and cognitive plasticity. Here, we asked how individual variability of social profiles is shaped at adolescence and whether the profiles are associated with regional brain metabolites and gene expressions in the adult brain. At adolescence we determined a ‘dominant’ profile expressing more dominance, a ‘submissive’ profile expressing more submission and an ‘explorer’ profile showing more novelty exploration than social interaction. Adolescent social behaviors are conserved at adulthood. Our data suggest that dominance tendencies already present at adolescence are likely to stabilize throughout life, thus shaping future social behaviors. Our results show that social profiles are not related to sex and life environment. However, being more dominant, interactive and socially motivated shape dopaminergic olfactory activity at adolescence. Also, showing the explorer or submissive profiles is associated with an opposite serotonin pattern in the cerebellum, but a similar kynurenine pattern in the prefrontal cortex and cerebellum, thus pointing toward major neurotransmitter systems in key regions for brain health. This work opens new perspectives on the importance of studying social profiles early in life and the individual neurobiological associated features that could potentially predict individual vulnerability.