Abstract
Early life stress (ELS) shapes the way individuals cope with future situations. Animals use cognitive flexibility to cope with their ever-changing environment and this is mainly processed in forebrain areas. We investigated the performance of juvenile gilthead seabream, previously subjected to an ELS regime. ELS fish showed overall higher brain catecholaminergic (CA) signalling and lower brain derived neurotrophic factor (bdnf) and higher cfos expression in region-specific areas. All fish showed a normal cortisol and serotonergic response to acute stress. Brain dopaminergic activity and the expression of the α2Α adrenergic receptor were overall higher in the fish homologue to the lateral septum (Vv), suggesting that the Vv is important in CA system regulation. Interestingly, ELS prevented post-acute stress downregulation of the α2Α receptor in the amygdala homologue (Dm3). There was a lack of post-stress response in the β2 adrenergic receptor expression and a downregulation in bdnf in the Dm3 of ELS fish, which together indicate an allostatic overload in their stress coping ability. ELS fish showed higher neuronal activity (cfos) post-acute stress in the hippocampus homologue (Dlv) and the Dm3. Our results show clear long-term effects on limbic systems of seabream that may compromise their future coping ability to environmental challenges.
Highlights
Animals cope with stressful situations in different manners
This is in agreement with mammalian literature on effects of early life stress (ELS) on catecholamine function, in terms of lateral septum and amygdala function[9,27], which highlights the relevance of using fish models in the study of central nervous system function in vertebrates
We found long-term effects on seabream limbic systems sampled at either basal levels or after an acute stress test, approximately 5 months after being subjected to an early life stress (ELS) regime for 2 weeks
Summary
Animals cope with stressful situations in different manners. Generally, an interaction between genes and both current and past environments gives rise to these individual variations in stress coping. Experiencing chronic stress during early life stages (including adolescence), may lead to long-term physiological and behavioural changes which may not be adaptive to a current non-stressful environment This leads to normally adaptive responses over-riding self-correcting tendencies of emotional mechanisms, leading to pathologies[6,7,8,9]. We report for the first time, stress resilient mechanisms involving catecholamine and region-specific adrenergic receptor expression in fish This is in agreement with mammalian literature on effects of ELS on catecholamine function, in terms of lateral septum and amygdala function[9,27], which highlights the relevance of using fish models in the study of central nervous system function in vertebrates
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