title: Identification of environmental stressors and validation of light preference as a measure of anxiety in larval zebrafish.
abstract: Larval zebrafish, with a simple and transparent vertebrate brain composed of ~100 K neurons, is well suited for deciphering entire neural circuit activity underlying behavior. Moreover, their small body size (~4-5 mm in length) is compatible with 96-well plates, making larval zebrafish amenable to high content screening. Despite these attractive features, there is a scarcity of behavioral characterizations in larval zebrafish compared to other model organisms as well as adult zebrafish.
  
  
  
  In this study, we have characterized the physiological and behavioral responses of larval zebrafish to several easily amenable stimuli, including heat, cold, UV, mechanical disturbance (MD), and social isolation (SI). These stimuli are selected based on their perceived aversive nature to larval zebrafish. Using a light/dark choice paradigm, in which larval zebrafish display an innate dark avoidance behavior (i.e. scotophobia), we find that heat, cold and UV stimuli significantly enhance their dark avoidance with heat having the most striking effect, whereas MD and SI have little influence on the behavior. Surprisingly, using the cortisol assay, a physiological measure of stress, we uncover that all stimuli but heat and SI significantly increase the whole body cortisol levels.
  
  
  
  These results identify a series of stressors that can be easily administered to larval zebrafish. Those stimuli that elicit differential responses at behavioral and physiological levels warrant further studies at circuit levels to understand the underlying mechanisms. The findings that various stressors enhance while anxiolytics attenuate dark avoidance further reinforce that the light/dark preference behavior in larval zebrafish is fear/anxiety-associated.
authors.affiliation: State Key Laboratory of Genetic Engineering, Department of Genetics, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Graduate Program in Bioengineering, University of California, San Francisco, CA, USA.|Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA.
authors.forename: Harrison
authors.initials: H
authors.lastname: Liu
authors.affiliation: Graduate Program in Bioengineering, University of California, San Francisco, CA, USA.|Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Huang
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, Programs in Human Genetics and Biological Sciences, Wheeler Center for the Neurobiology of Addiction, University of California, San Francisco, CA, USA. Mahendra.wagle@gmail.com.
authors.forename: Mahendra
authors.identifier: 0000-0003-1802-9330
authors.initials: M
authors.lastname: Wagle
authors.affiliation: State Key Laboratory of Genetic Engineering, Department of Genetics, School of Life Sciences, Fudan University, Shanghai, China. Su.guo@ucsf.edu.|Department of Bioengineering and Therapeutic Sciences, Programs in Human Genetics and Biological Sciences, Wheeler Center for the Neurobiology of Addiction, University of California, San Francisco, CA, USA. Su.guo@ucsf.edu.
authors.forename: Su
authors.initials: S
authors.lastname: Guo
mesh_terms: D000818:Animals; D001007:Anxiety / Q000378:metabolism; D001362:Avoidance Learning; D002755:Choice Behavior; D003080:Cold Temperature; D004777:Environment; D006358:Hot Temperature; D006854:Hydrocortisone / Q000378:metabolism; D007814:Larva; D008027:Light; D023421:Models, Animal; D009038:Motion; D009043:Motor Activity; D010812:Physical Stimulation; D011581:Psychological Tests; D012934:Social Isolation / Q000523:psychology; D013315:Stress, Psychological / Q000378:metabolism; D015027:Zebrafish
chemical_list: D006854:Hydrocortisone
keywords: Anxiety; Behavior; Cortisol; Larvae; Light–dark preference; Stressor; Zebrafish