Kentrop, J. | Search bioRxiv

bioRxiv2020

Effects of maternal deprivation and complex housing on pro-social behavior in rats: An automated, operant task examining motivation to liberate a trapped conspecific

Early life environment influences the development of various aspects of social behavior, particularly during sensitive developmental periods. Here, we aimed to study how challenges in the early postnatal period or (early) adolescence affect pro-social behavior. To this end, we adapted an existing paw operated liberation task to an automated operant task, to measure motivation (by progressively increasing required lever pressing) to liberate a trapped conspecific. Liberation of the trapped rat resulted either in social contact, or in liberation into a separate compartment. Additionally, a condition was tested in which both rats could freely move in two separate compartments and lever pressing resulted in social contact. When partners were not trapped, rats were more motivated to press the lever for opening the door than in either of the trapped configurations. Contrary to our expectation, the trapped configuration resulted in a reduced motivation to act. Early postnatal stress (24h maternal deprivation on postnatal day 3) did not affect behavior in the liberation task. However, rearing rats from early adolescence onwards in complex housing conditions (Marlau cages) reduced the motivation to door opening, both in the trapped and freely moving conditions, while motivation for a sucrose reward was not affected.

animal behavior and cognition↗

bioRxiv2019

The behavioral phenotype of early life adversity: a 3-level meta-analysis of rodent studies

1BackgroundAltered cognitive performance has been suggested as an intermediate phenotype mediating the effects of early life adversity (ELA) on later-life development of mental disorders, e.g. depression. Whereas most human studies are limited to correlational conclusions, rodent studies can prospectively investigate how ELA alters cognitive performance in a number of domains. Despite the vast volume of reports, no consensus has yet been reached on the i) behavioral domains being affected by ELA and ii) the extent of these effects.\n\nMethodsTo test how ELA (here: aberrant maternal care) affects specific behavioral domains, we used a 3-level mixed-effect meta-analysis, a flexible model that accounts for the dependency of observations. We thoroughly explored heterogeneity with MetaForest, a machine-learning data-driven analysis never applied before in preclinical literature. We validated the robustness of our findings with substantial sensitivity analyses and bias assessments.\n\nResultsOur results, based on >400 independent experiments, yielded >700 comparisons, involving ~8600 animals. Especially in males, ELA promotes memory formation during stressful learning but impairs non-stressful learning. Furthermore, ELA increases anxiety and decreases social behavior. The ELA phenotype was strongest when i) combined with other negative experiences (\"hits\"); ii) in rats; iii) in ELA models of ~10days duration.\n\nConclusionProspective and well-controlled animal studies demonstrate that ELA durably and differentially impacts distinct behavioral domains. All data is now easily accessible with MaBapp (https://osf.io/ra947/), which allows researchers to run tailor-made meta-analyses on the topic, thereby revealing the optimal choice of experimental protocols and study power.

neuroscience↗