Abstracts Category : Other

The Effects of Social Status on Dopaminergic Regulation of Neural Circuit Activation and Behavior

by Katie Clements

Social hierarchies can be observed within communities across many species and allow for proper allocation of resources. When forming social hierarchies, animals that display the most aggressive behaviors generally emerge as dominant, while less aggressive animals are relegated to a subordinate role. The aim of this study is to address the neural bases of social regulation using zebrafish (Danio rerio) as a model organism. When paired, zebrafish form dominance hierarchies that consist of socially dominant and subordinate fish. To better understand the effects of social dominance on nervous system function we investigated the influence of social experience on the escape and swim behaviors. Using a non-invasive technique of recording field potentials, we monitored escape and swimming behavior between fish of known social status. We showed that social status affects neural activation underlying swimming and escape behaviors. Subordinates favor escape over swim, while dominants favor swim over escape. We hypothesized that a neuromodulator associated with social regulation and aggression, dopamine (DA), may influence the activation of the two underlying neural circuits responsible for these behaviors in a social status-dependent manner. To test this hypothesis, we initially looked at whether the supply of DA influenced differences in swimming and escape behavior. We augmented levels of DA through injection and observed no significant changes in the escape or swimming behavior of dominants or subordinates. Next, we determined if the interpretation of DA, via DA receptors, influenced the status-dependent behavioral differences. We manipulated the activation of DA receptors through injection of DA specific agonists and antagonists. First, antagonizing the dopamine 1 receptor (D1) decreased dominant swimming frequency and increased escape probability, while having no effect on either behavior in subordinates. Activating the D1 receptor caused no changes in escape probability or swimming frequency in either social phenotype. Second, neither application of dopamine 2 receptor (D2) agonist nor antagonist significantly altered escape probability in either social phenotype; however, blocking the D2 receptor reduced dominant swimming frequency. Finally, antagonizing the dopamine 3 receptor (D3) lowered subordinates probability of escape with no change in swimming frequency, while showing no effect on dominant behavior. Activating the D3 receptor had no effect on dominant or subordinate escape behavior, but decreased dominant swimming. Taken together, these results suggest that the social status-dependent differences in escape and swimming behaviors of zebrafish may be influenced by dopamine receptor activation