Social Regulation of the Escape and Swim Motor Circuits in Dopamine Receptor Type 1 Mutant Zebrafish (Danio rerio)

Abstract

Dominance hierarchies are an evolutionary mechanism to ensure the stability of animal groups by enabling the division of resources like food and mates according to social rank. Once dominance is established, the behavior pattern of individual group members shifts according to their social rank. We are motivated to better understand the neural bases of social behavior and how social activity influence nervous system function particularly the role of neuromodulators in regulating spinal motor circuits. Using zebrafish as a model organism, we tested the importance of the dopamine type 1 receptor (DRD1) in regulating social activity and spinal motor circuits in socially dominant and submissive fish by genetically knocking the DRD1 receptor.

Our motivation stems out of the fact that in many animal species dopamine plays an important role in regulating aggression, motivation and spinal motor activity. However, it remains poorly understood how social factors can influence dopaminergic signaling and its impact on motor function. We focused out attention on two easily quantifiable behaviors: the startle escape response and swimming behaviors.

In wildtype zebrafish, we found that subordinate animals display an elevated startle response sensitivity and reduced swimming activity compared to dominant animals. However, preliminary results show that although the DRD1 KO animals display similar status-dependent behavior patterns compared to wildtype pairs, these differences are less distinct. DRD1 KO subordinates continue to display heightened escape response sensitivity and reduced swimming activity compared to dominants, but those differences are less discernable. We aim to verify these results with a larger sample size. If confirmed, our results would suggest that the DRD1 receptor potentially plays an important role in regulating motor activity in a socially status-dependent manner.