Complex housing in adulthood state-dependently affects the excitation-inhibition balance in the infralimbic prefrontal cortex of male C57Bl/6 mice.

The prefrontal cortex (PFC) plays an important role in social behavior and is sensitive to stressful circumstances. Challenging life conditions might change PFC function and put individuals at risk for maladaptive social behavior. The excitation-inhibition (EI) balance of prefrontal neurons appears to play a crucial role in this process.

Complex Housing, but Not Maternal Deprivation Affects Motivation to Liberate a Trapped Cage-Mate in an Operant Rat Task.

Early life environment influences the development of various aspects of social behavior, particularly during sensitive developmental periods. We studied how challenges in the early postnatal period or (early) adolescence affect pro-social behavior. To this end, we designed a lever-operated liberation task, to be able to measure motivation to liberate a trapped conspecific (by progressively increasing required lever pressing for door-opening).

The continued need for animals to advance brain research.

Policymakers aim to move toward animal-free alternatives for scientific research and have introduced very strict regulations for animal research. We argue that, for neuroscience research, until viable and translational alternatives become available and the value of these alternatives has been proven, the use of animals should not be compromised.

The relevance of a rodent cohort in the Consortium on Individual Development.

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.

Pro-social preference in an automated operant two-choice reward task under different housing conditions: Exploratory studies on pro-social decision making.

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.

Maternal care of heterozygous dopamine receptor D4 knockout mice: Differential susceptibility to early-life rearing conditions.

The differential susceptibility hypothesis proposes that individuals who are more susceptible to the negative effects of adverse rearing conditions may also benefit more from enriched environments. Evidence derived from human experiments suggests the lower efficacy dopamine receptor D4 (DRD4) 7-repeat as a main factor in exhibiting these for better and for worse characteristics. However, human studies lack the genetic and environmental control offered by animal experiments, complicating assessment of causal relations.

The effects of different rearing conditions on sexual maturation and maternal care in heterozygous mineralocorticoid receptor knockout mice.

Sexual and social development is affected by a complex interplay between genetic makeup and the early-life rearing environment. While many rodent studies focused primarily on the detrimental effects of early-life stress, human literature suggests that genetic susceptibility may not be restricted to negative environments; it may also enhance the beneficial effects of positive rearing conditions. To examine this interaction in a controlled setting, heterozygous mineralocorticoid receptor knockout (MR) mice and control litter mates were exposed to a limited nesting/bedding (LN, impoverished), standard nesting (SN, control) or communal nesting (CN, enriched) paradigm from postnatal day 2-9 (P2-P9).

Effects of Maternal Deprivation and Complex Housing on Rat Social Behavior in Adolescence and Adulthood.

Early life context and stressful experiences are known to increase the risk of developing psychiatric disorders later in life, including disorders with deficits in the social domain. Our study aimed to investigate the influence of early life environment on social behavior in a well-controlled animal model. To this end we tested the effects of maternal deprivation (MD) on rat social play behavior in adolescence and social interaction in adulthood.

The added value of rodent models in studying parental influence on offspring development: opportunities, limitations and future perspectives.

Over the past decades, the influence of parental care on offspring development has been a topic of extensive research in both human and animal models. Rodent models offer several unique advantages over human studies, allowing for higher levels of environmental control, exploration of interventions, genetic control and examination of underlying neurobiological mechanisms in greater spatiotemporal detail. Although exploitation of these opportunities has led to increased understanding of the neurobiological mechanisms underlying susceptibility to the early-life environment, translation of results to human parenting and child development appears to be challenging.

Mifepristone Treatment during Early Adolescence Fails to Restore Maternal Deprivation-Induced Deficits in Behavioral Inhibition of Adult Male Rats.

Early life adversity has a profound impact on brain development and later life health. Animal models have provided insight how early life stress programs stress responsiveness and might contribute to the development of psychiatric disorders. In the present study, the long-term effects of maternal deprivation (MD) on behavioral inhibition and attention were examined in adult male Wistar rats.

Complex Living Conditions Impair Behavioral Inhibition but Improve Attention in Rats.

Rapid adaptation to changes, while maintaining a certain level of behavioral inhibition is an important feature in every day functioning. How environmental context and challenges in life can impact on the development of this quality is still unknown. In the present study, we examined the effect of a complex rearing environment during adolescence on attention and behavioral inhibition in adult male rats.

Effects of intranasal oxytocin administration on memory for infant cues: moderation by childhood emotional maltreatment.

Oxytocin has been implicated in parent-infant attachment and social recognition. With respect to emotion recognition memory, both memory-enhancing and impairing effects have been observed, suggesting an influence of individual factors. We assessed the effects of oxytocin on memory for infant cues, and whether these effects are moderated by self-reported childhood emotional maltreatment.

Salivary oxytocin mediates the association between emotional maltreatment and responses to emotional infant faces.

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.

Deletion of the forebrain mineralocorticoid receptor impairs social discrimination and decision-making in male, but not in female mice.

Social interaction with unknown individuals requires fast processing of information to decide whether it is friend or foe. This process of discrimination and decision-making is stressful and triggers secretion of corticosterone activating mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). The MR is involved in appraisal of novel experiences and risk assessment.

One doll fits all: validation of the Leiden Infant Simulator Sensitivity Assessment (LISSA).

Children vary hugely in how demanding of their caregivers they are. This creates differences in demands on parents during observation, making the comparison of sensitivity between parents difficult. It would therefore be of interest to create standard situations in which all caregivers are faced with the same level of demand.

Mifepristone treatment affects the response to repeated amphetamine injections, but does not attenuate the expression of sensitization.

Unlabelled: Rationale Glucocorticoid hormones facilitate sensitization to repeated administration of psychostimulants, an effect that is mediated by glucocorticoid receptors (GRs). It is still unclear, however, at which stage of psychomotor sensitization are stress and GR-mediated effects involved.

Objectives: In the present study, we have tested the hypothesis that GR-mediated effects during the phase of repeated amphetamine injections play a crucial role in the long-term expression of sensitization.

Elevated Salivary Levels of Oxytocin Persist More than 7 h after Intranasal Administration.

We addressed the question how long salivary oxytocin levels remain elevated after intranasal administration, and whether it makes a difference when 16 or 24 IU of oxytocin administration is used. Oxytocin levels were measured in saliva samples collected from 46 female participants right before intranasal administration (at 9:30 a.m.

Interplay of maternal care and genetic influences in programming adult hippocampal neurogenesis.

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.

Development of individual differences in stress responsiveness: an overview of factors mediating the outcome of early life experiences.

Rationale: Human epidemiology and animal studies have convincingly shown the long-lasting impact of early life experiences on the development of individual differences in stress responsiveness in later life. The interplay between genes and environment underlies this phenomenon.

Objectives: We provide an overview of studies investigating the impact of early life experiences on the development of individual differences in neuroendocrine stress responsiveness in adulthood and address (1) impact of environment on later stress phenotypes, (2) role of genetic factors in modulating the outcome of environment, and (3) role of nonshared environmental experience in the outcome of gene × environment interplays.

Brain development under stress: hypotheses of glucocorticoid actions revisited.

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.

Stress and addiction: glucocorticoid receptor in dopaminoceptive neurons facilitates cocaine seeking.

The glucocorticoid receptor is a ubiquitous transcription factor mediating adaptation to environmental challenges and stress. Selective Nr3c1 (the glucocorticoid receptor gene) ablation in mouse dopaminoceptive neurons expressing dopamine receptor 1a, but not in dopamine-releasing neurons, markedly decreased the motivation of mice to self-administer cocaine, dopamine cell firing and the control exerted by dopaminoceptive neurons on dopamine cell firing activity. In contrast, anxiety was unaffected, indicating that glucocorticoid receptors modify a number of behavioral disorders through different neuronal populations.

Maternal environment influences cocaine intake in adulthood in a genotype-dependent manner.

Background: Accumulating epidemiological evidence points to the role of genetic background as a modulator of the capacity of adverse early experiences to give rise to mental illness. However, direct evidence of such gene-environment interaction in the context of substance abuse is scarce. In the present study we investigated whether the impact of early life experiences on cocaine intake in adulthood depends on genetic background.

Gene-environment interactions in vulnerability to cocaine intravenous self-administration: a brief social experience affects intake in DBA/2J but not in C57BL/6J mice.

Rationale: Individual differences in cocaine-taking behavior and liability to develop abuse are clearly observed, but underlying mechanisms are still poorly understood. A role for gene-environment interactions has been proposed but remains hypothetical.

Objectives: We investigated whether gene-environment interactions influence intravenous cocaine self-administration (SA) in mice.