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Background: Adult hippocampal neurogenesis, which is involved in the physiopathology of hippocampal functions, is genetically determined and influenced by early life events. However, studies on the interaction of these determining forces are lacking. This prompted us to investigate whether adult hippocampal neurogenesis can be modulated by maternal care and whether this influence depends upon the genetic background of the individual. Methods: We used a model of fostering that allows singling out the influence of the genetic make-up of the pups on the outcome of maternal behavior. Mice from two different inbred strains (C57BL/6J and DBA/2J) known to differ in their baseline neurogenesis as well as in their sensitivity to the influence of environmental experiences were raised by nonrelated mothers from the AKR/Ola (AKR) and C3H/He (C3H) strains exhibiting low- and high-pup-oriented behavior, respectively. Neurogenesis was then assessed in the dentate gyrus of the adult adopted C57BL/6J and DBA/2J mice. Results: We show that both the number and the morphological features of newborn granule cells in the dentate gyrus are determined by the maternal environment to which mice were exposed as pups and that this sensitivity to maternal environment is observed only in genetically vulnerable subjects. Conclusions: Altogether, our data indicate interplay between early environment and the genetic envelop of an individual in determining adult hippocampal neurogenesis. Our experimental approach could thus contribute to the identification of factors determining the neurogenic potential of the adult hippocampus. [ABSTRACT FROM AUTHOR]

One of the features of the Consortium on Individual Development is the existence of a rodent cohort, in parallel with the human cohorts. Here we give an overview of the current status. We first elaborate on the choice of rat and mouse models mimicking early life adverse or beneficial conditions during development. We performed a systematic literature search on early life adversity and adult social behavior to address the status quo. Next, we describe the behavioral tasks we used and designed to examine behavioral control and social competence in rodents. The results so far indicate that manipulation of the environment in the first postnatal week only subtly affects social behavior. Stronger effects were seen in the model that targeted early adolescence; once adult, these rats are characterized by increased attention, a higher degree of impulsiveness and reduced social interest in peers. Many experiments in our rodent models with tightly controlled conditions were inspired by findings in human cohorts, and now allow in-depth mechanistic investigations. Vice versa, some of the findings in rodents are currently followed up by dedicated investigations in the human cohorts. This exemplifies the added value of animal investigations in a consortium encompassing primarily human developmental cohorts. [ABSTRACT FROM AUTHOR]

In this study, we aimed to develop a behavioral task that measures pro-social decision making in rats. A fully automated, operant pro-social two-choice task is introduced that quantifies pro-social preferences for a mutual food reward in a set-up with tightly controlled task contingencies. Pairs of same-sex adult Wistar rats were placed in an operant chamber divided into two compartments (one rat per compartment), separated by a transparent barrier with holes that allowed the rats to see, hear, smell, but not touch each other. Test rats could earn a sucrose pellet either for themselves (own reward) or for themselves and the partner (both reward) by means of lever pressing. On average, male rats showed a 60 % preference for the lever that yielded a food reward for both themselves and their partner. In contrast, females did not show lever preference, regardless of the estrous cycle phase. Next, the impact of juvenile environmental factors on male rat social decision making was studied. Males were group-housed from postnatal day 26 onwards in complex housing Marlau™ cages that provided social and physical enrichment and stimulation in the form of novelty. Complex housed males did not show a preference for the pro-social lever. [ABSTRACT FROM AUTHOR]

Abstract: Childhood emotional maltreatment has been associated with a higher risk for maltreating one's own offspring. In the current study, we explored a possible role of oxytocin in mediating the association between childhood emotional maltreatment and participants' interpretation of infant facial expressions. Oxytocin levels were measured in 102 female participants using saliva samples. They rated the mood of thirteen infants with happy, sad and neutral facial expressions. Emotional maltreatment indirectly influenced responses to happy infant faces by modulating oxytocin levels: higher self-reported emotional maltreatment was related to higher levels of salivary oxytocin which were in turn related to a more positive evaluation of happy infant expressions, but not to the evaluation of sad infant expressions. Oxytocin receptor polymorphism rs53576 did not moderate the relation between maltreatment experiences and salivary oxytocin levels. Early emotional maltreatment might indirectly affect emotional information processing by altering the oxytonergic system. [Copyright &y& Elsevier]

Abstract: One of the conundrums in today''s stress research is why some individuals flourish and others perish under similar stressful conditions. It is recognized that this individual variability in adaptation to stress depends on the outcome of the interaction of genetic and cognitive/emotional inputs in which glucocorticoid hormones and receptors play a crucial role. Hence one approach towards understanding individual variation in stress coping is how glucocorticoid actions can change from protective to harmful. To address this question we focus on four hypotheses that are connected and not mutual exclusive. First, the classical Glucocorticoid Cascade Hypothesis, in which the inability to cope with chronic stress causes a vicious cycle of excess glucocorticoid and downregulation of glucocorticoid receptors (GR) in the hippocampus triggering a feed-forward cascade of degeneration and disease. Second, the Balance Hypothesis, which takes also the limbic mineralocorticoid receptors (MR) into account and proposes that an integral limbic MR:GR imbalance is causal to altered processing of information in circuits underlying fear, reward, social behaviour and resilience, dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and impairment of behavioural adaptation. The MR:GR balance is altered by gene variants of these receptor complexes and experience-related factors, which can induce lasting epigenetic changes in the expression of these receptors. A particular potent epigenetic stimulus is the maternal environment which is fundamental for the Maternal Mediation Hypothesis. The outcome of perinatal gene×environment interaction, and thus of MR:GR-mediated functions depends however, on the degree of ‘matching’ with environmental demands in later life. The Predictive Adaptation Hypothesis therefore presents a conceptual framework to examine the role of glucocorticoids in understanding individual phenotypic differences in stress-related behaviours over the lifespan. [Copyright &y& Elsevier]