Subterranean Fishes of the World

4316

2019

AIM 2019

66

Responding appropriately to stress is essential for survival. In humans, childhood trauma can lead to debilitating neuropsychiatric disorders such as generalized anxiety disorder and post-traumatic stress disorder. Despite the major social impact of early childhood trauma, little is known about how chronic early life stress (ELS) affects brain-wide circuits that modulate anxiety or the genetic and neuronal modulators of stress. The zebrafish has been a powerful model to investigate the genetic and neurodevelopmental processes underlying many behaviors. In addition, the small size and transparency of the larvae allows for whole-brain imaging and elucidation of the neural circuits involved during a behavioral response. We recently developed a zebrafish model of ELS and showed that juveniles that have gone through chronic stress as larvae have exacerbated behavioral stress responses later in life. While genetic models like the zebrafish have provided insight into the neurochemical and neuroanatomical pathways that underlie stress, little is known about how evolutionary processes and naturally occurring variation contribute to the diverse responses to stressful stimuli observed in the animal kingdom. The Mexican cavefish is a powerful system to address how altered genetic and neuronal systems can give rise to aberrant behaviors. We have shown that compared to the more ancestral surface eyed forms of the species, the cave morphs displayed reduced behavioral measures of stress in a novel tank assay, characterized by reduced exploratory behavior and increased immobility, akin to ‘freezing’. These stress responses are reduced when both forms are treated with an anxiolytic drug, buspirone, fortifying that notion that the behavior represents a conserved stress state. Convergence of diminished stress behavior was evident in at least two other independently evolved cave forms. Together, using both the zebrafish and the Mexican cavefish, future investigations into the genetic and neural circuits involved in these behavioral changes will aid in understanding the basic principles underlying stress and anxiety, and reveal how evolutionary processes contribute

1

Astyanax Interrnational Meeting