The plus maze and scototaxis test are not valid behavioral assays for anxiety assessment in the South African clawed frog
There are no behavioral models for testing anxiety in amphibians, a group of animals widely used for developmental, ecotoxicological, and genetic research. We aimed to validate two common rodent paradigms, the plus maze and the scototaxis test, for use in the aquatic African clawed frog (Xenopus laevis). We predicted: (a) that frogs would prefer the dark, vs. light, portions of the testing arenas (face validity), (b) that this behavior could be altered with acute administration of anxio-selective drugs (construct validity), and (c) that time spent in the dark portions of the arenas would be positively correlated (predictive validity). Prior to testing, frogs were treated with fluoxetine (selective serotonin reuptake inhibitor [SSRI]), desipramine (serotonin- and norepinephrine-reuptake inhibitor), caffeine (methylxanthine, adenosine receptor antagonist, phosphodiesterase inhibitor), saline, or were left unmanipulated. Each drug was administered acutely (1 h prior to testing; caffeine) or subacutely (24, 3, and 1 h prior to testing; fluoxetine, desipramine) at one of three doses. Plus maze and scototaxis testing were separated by 1 week; each frog completed both behavioral tasks and was treated with the same drug regimen prior to testing. Overall, both tests showed face validity, however, data suggest these paradigms lack both construct and predictive validity.
KeywordsEcotoxicology SSRI Amphibian Caffeine PPCP
Pharmaceutical and personal care product
Research Domain Criteria
Selective serotonin reuptake inhibitor
We would like to thank Paul Duggan, Rebekah Salinas, Christian Thomas, and Dr. Kurt Caswell for their help on this project. We would also like to thank the Texas Tech Honors College (Undergraduate Research Scholar program) and the NSF-funded PRISM program (www.math.ttu.edu/outreach/prism) for supporting RBC. We especially thank the PRISM PIs (Drs. G. Brock Williams, Sophia Jang, Nancy McIntyre, Jaclyn Canas-Carrell, and Jerry Dwyer), Jessica Spott, Lori Lightfoot, and Jerylme Robins for their support. All applicable international, national, and Texas Tech University Institutional Animal Care and Use Committee (IACUC) guidelines were followed. Texas Tech University is Association for Assessment and Accreditation of Laboratory Animal Care accredited. We also thank two anonymous reviewers for their helpful and constructive comments on a previous version of this manuscript, their comments no doubt improved the final product.
This work was partially supported by the National Science Foundation under Grant Nos. 1035096 (PRISM) and 1656734 (IOS, awarded to JAC and BNH), and by the Texas Tech University (TTU) Center for Active Learning and Undergraduate Engagement (now TrUE). This project was conducted for the fulfillment of R. Boone Coleman’s Honor’s Thesis.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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