What makes some individuals fitter than others: The developmental underpinnings of stress resilience

Abstract

Stress is a systemic physiological and behavioural response to what an organism perceives as threat. Response to the same stressful event varies within a population, with some individuals emerging out more resilient than others. Though recent research using adult rodents and post-mortem human samples has implicated some molecular and environmental factors as being involved in stress resilience in retrospect, little is known about early life stress resilience. In order to understand whether vertebrates do indeed display differential stress response early in life, and subsequently, to study the contribution of the developing brain to the specification of this phenomenon, we employed the developing zebrafish as a model. Zebrafish exhibit stress responsive behaviour early in life, and exploiting this advantage, we designed behavioural assays to quantify recovery from intensely stressful events. Using these assays, we show that stress resilient subsets exist in genetically identical populations of zebrafish from very early stages of development. Further, this attribute is maintained as the fish grow to become juvenile and adults and is passed on to the next generation. Fish that were attributed to be resilient in early life showed better fitness to survive to adulthood and tended to be more social in comparison to susceptible fish. Gene expression analyses comparing the response of resilient and susceptible larvae to stress showed that the resilient individuals turn on a transcriptional program minutes after the stressful event, in contrast to susceptible individuals, which do not show this robust response. Current experiments are focusing on understanding the cellular and molecular factors which might be key players in early life stress resilience.

Publication
In Neurizons 2020