Measuring Behavior 2005: Guo et al.

Measuring reward-associated behaviors in zebrafish

S. Guo, B. Lau and S. Bretaud

Department of Biopharmaceutical Sciences, Programs in Human Genetics and Biological Sciences, University of California, San Francisco, CA, USA

Reward-associated behaviors are manifestations of sensory, motivational, and motor circuitries. How such behaviors are developed and regulated at molecular and cellular levels are not well understood.

While assays are established for measuring reward-associated behaviors in rodents, not much has been done in a recently established vertebrate model organism for genetics, the zebrafish Danio rerio, which offers an excellent opportunity to link genes, neuronal circuitry, and behavior.

Our goal is to develop assays that can assess reward-associated behaviors in zebrafish; moreover, we intend to make these assays high throughput for the purpose of large-scale genetic screening.

In this paper, we focus on the methodological aspects of our work, including psychostimulant modulated locomotor activity, conditioned place preference, and ‘selfadministration’- like behaviors. For measuring locomotor activity, we focused on the effects of alcohol on larval zebrafish. Larval zebrafish are from 5 day to two weeks old, and are free living, and capable of food hunting and escaping from predators. Using a computer-assisted video tracking system, we are able to quantitatively monitor their locomotor activity in a group setting. We found that alcohol exhibit a biphasic response on larval zebrafish behavior: at low concentrations, it increases their locomotor activity, while at high concentrations, it depresses their locomotor activity. For testing conditioned place preference, we adopted a paradigm similar to that used in rodent studies, and focus on examining the reinforcing effects of food as well as morphine. We found that both food and morphine can elicit a significant preference in zebrafish. Moreover, by devising a choice chamber assay, we are able to monitor morphine and food preference behavior in larval zebrafish. The choice chamber assay is to some extent similar to ‘self-administration’ paradigm used in rodents, because animals are tested directly for their preference for the substance.

Together, we have established assays assessing reward-associated behaviors in zebrafish. Our current as well as future efforts are to make these assays more robust and high throughput for the purpose of large-scale genetic screening. Our planned multi-disciplinary approaches including behavior, genetics, molecular and cellular methodologies promise to provide crucial insights into such complex human behaviors as choice making.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.