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Locomotor activity changes on zebrafish larvae with different 2,2′,4,4′-tetrabromodiphenyl ether (PBDE-47) embryonic exposure modes

Zhao, Jing, Xu, Ting, Yin, Da-Qiang
Chemosphere 2014 v.94 pp. 53-61
Danio rerio, flame retardants, larvae, locomotion, neurotoxicity, photoperiod, pollution, polybrominated diphenyl ethers
Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants and are banned around the world as potent environmental contaminants. PBDE-47 is the most concerned PBDE with its environmental prevalence and various toxicity characteristics including neurotoxicity. In this paper, we studied larval zebrafish behavioral alterations caused by PBDE-47 neurotoxicity. The light–dark cycle stimulation was used to investigate the locomotor changes of zebrafish larvae at different ages (4–6day post-fertilization, dpf) after PBDE-47 exposure (5, 50, 500μgL−1). Three exposure modes, namely continuous exposure, early pulse exposure and interval exposure, were adopted to assess and compare the impacts of exposure modes on larval zebrafish locomotion. Our results showed that locomotor effects upon PBDE exposure depended on the specific exposure mode studied. In the early pulse exposure mode, the locomotion of zebrafish larvae did not change significantly at all PBDE-47 concentrations tested. In contrast, for both the continuous exposure and interval exposure modes, the highest dose of PBDE-47 (500μgL−1) elicited pronounced hypoactivity at 5dpf during dark periods except for the initial one. However, at 6dpf, hypoactivity was only observed in the continuously exposed zebrafish larvae (to an even higher degree compared to 5dpf), but not in the interval exposure treatment group. Our results suggested that the conventional, continuous exposure mode might not be enough to evaluate the toxicity of chemicals in the real environments.