Of Hamsters and Zebrafish: Stress-Induced Neuronal & Phenotypic Plasticity

My dissertation investigates how stressful experiences induce neural and phenotypic plasticity in zebrafish and Syrian hamsters. Environmental stressors such as chemical pollution have been identified as the primary risk to health worldwide, and induce widespread changes in organism behavior, physiology, and neural systems. Reactivity to stressors differs between individuals and populations, suggesting that individuals vary in their stress coping strategies and their susceptibility to the negative consequences of stress. Social experience such as juvenile social play or social dominance status in a dominance hierarchy can modify how individuals respond to stressors and is associated with altered experience-dependent neural plasticity. This dissertation assessed differences in stress reactivity and the neural plasticity that may be driving these individual differences in two model species for toxicology and social stress research across four aims. The first aim asked how exposure to cadmium toxicity affects group decision-making and social behavior in zebrafish. The second aim categorized behavioral and physiological variation between two wild populations of zebrafish from environments with differing ecological factors. Aim three asked how juvenile social play in Syrian hamsters promotes resistance to social stressors and alters neural plasticity in the ventromedial prefrontal cortex and basolateral amygdala. The fourth aim investigated how social dominance encounters generate plasticity in a medial amygdala to bed nucleus of the stria terminalis pathway that may promote stress resistance. My findings highlight the myriad ways external stressors disrupt species-typical behavior. Further, I show that both juvenile social play experience and achieving a dominant social status in adulthood promotes stress resistance.