Social Interaction in Zebrafish: Effects of Social Isolation on Behaviour, Neurochemistry, and Stress

Characterization and detailed analysis of social behaviour are necessary to further establish zebrafish as a model for developmental disorders such as Autism Spectrum Disorders and Fetal Alcohol Syndrome Disorder. Social isolation has been used as a tool to study regulation of social behaviour in various species before. The purpose of this thesis was to investigate how social isolation (during development or in adulthood) affects subsequent social and non-social behaviours. I also examined neurotransmitter systems associated with social interaction, namely dopamine and serotonin, and stress hormone cortisol, as isolated fish responded to novelty or to social stimuli. I found that life-long developmental isolation increased locomotor activity, and altered responses to social stimuli and dopaminergic metabolite levels. On the other hand, locomotor activity and social responses of socially raised zebrafish remained unchanged after chronic isolation in adulthood, but a reduction in serotonin metabolite levels was found in response to novelty and social interaction. Behavioural and physiological responses of fish isolated in adulthood were also affected by social stimulus type and prior social hierarchy status. Both developmental and chronic adult isolation reduced anxiety-related behaviour, and cortisol levels indicated that long-term social isolation is not stressful in zebrafish. Findings from zebrafish experiments are discussed in light of isolation literature in other social animals. These analyses help establish translationally relevant zebrafish research as a tool to simplify, explore, and understand behaviour and disorders involving social abnormalities in social vertebrates.Ph.D.2019-01-11 00:00:0