P.2.019 The mismatch hypothesis: a new way of linking early experiences and adult environment to vulnerability to stress

Abstract

Purpose of the study: Chronic stress is considered one of the main risk factors for depression. Interestingly, not all individuals develop psychopathology after chronic stress. In contrast to the prevailing view that stress effects are cumulative and increase stress vulnerability later in life, the recently formulated mismatch hypothesis proposes that individuals experiencing high levels of psychosocial stress early in life are programmed for dealing with high psychosocial stress and are therefore resilient to high stress levels in later life [1]. We here test this hypothesis by comparing the developmental effects of two different early life conditions, when tested under two opposite adult environments. Methods used: We used female BALB/c mice that underwent either adverse early life conditions (limited nesting material) or a supportive environment (early handling) from PND2 to PND9. At weaning, the animals of each group were assigned to either group housing (supportive environment) or single housing (social deprivation, adverse environment). At adulthood, we compared the molecular and the behavioural effects of the interaction between early and adult environment, in particular on anxiety like and depressive like behaviour.