Abstract
This study is an adaptation of the nicotine-evoked locomotor response (NLR) assay, which was originally utilized for phenotype-based neurotoxicity screening in zebrafish embryos. Zebrafish embryos do not exhibit spontaneous swimming until roughly 4 days post-fertilization (dpf), however, a robust swimming response can be induced as early as 36 hours post-fertilization (hpf) by means of acute nicotine exposure (30–240μM). Here, the NLR was tested as a tool for early detection of locomotor phenotypes in 36, 48 and 72 hpf mutant zebrafish embryos of the non-touch-responsive maco strain; this assay successfully discriminated mutant embryos from their non-mutant siblings. Then, methylmercury (MeHg) was used as a proof-of-concept neurotoxicant to test the effectiveness of the NLR assay as a screening tool in toxicology. The locomotor effects of MeHg were evaluated in 6 dpf wild type eleutheroembryos exposed to waterborne MeHg (0, 0.01, 0.03 and 0.1μM). Afterwards, the NLR assay was tested in 48 hpf embryos subjected to the same MeHg exposure regimes. Embryos exposed to 0.01 and 0.03μM of MeHg exhibited significant increases in locomotion in both scenarios. These findings suggest that similar locomotor phenotypes observed in free swimming fish can be detected as early as 48 hpf, when locomotion is induced with nicotine.
Highlights
Every one of the ~512 embryos tested with the nicotine-evoked locomotor response (NLR) paradigm exhibited locomotor output in response to acute nicotine exposure, which highlights the effectiveness and reliability of the NLR paradigm
Embryonic developmental stage had an effect on the NLR. 36 hpf embryos achieved overall lower maximum speeds than 48 hpf embryos in all nicotine concentrations tested (n = 12 embryos, P
In 48 hpf embryos, a dose of 120μM of nicotine delivered a satisfactory NLR that was not significantly different to the NLR evoked by 240μM, for this reason we concluded that the optimal experimental conditions for the NLR assay as a screening tool would be to trigger the response with 120μM of nicotine utilizing 48 hpf embryos
Summary
The zebrafish has emerged as a widely utilized aquatic model organism. The fecundity of this organism and the rapid development of its embryos enable scientists to perform large scale, phenotype-based screens in much shorter time frames than it would take to reproduce similar experiments in rodents [1]. With this premise in mind, a number of research groups have placed great interest in developing novel paradigms for behavioral phenotypebased screening in zebrafish embryos.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
