Citation:

Stevens, J., S. Padilla, D. DeMarini, D. Hunter, K. Martin, L. Thompson, Ian Gilmour, M. Hazari, AND A. Farraj. Zebrafish Locomotor Responses Reveal Irritant Effects of Fine Particulate Matter Extracts and a Role for TRPA1. TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 161(2):290-299, (2018).

Impact/Purpose:

Because of the unique PM sources and atmospheric conditions in a given ambient air shed, no two air sheds are identical resulting in a near infinite number of PM samples from different sources with little to no information on toxicity potential, impeding risk assessment. Currently, most toxicity assessments of specific air sheds are protracted, dependent on data from rodent and/or in vitro studies. The increased throughput of the zebrafish locomotor assay may markedly accelerate the pace at which toxicity information about specific PM sources and components are acquired and processed. As a result, comprehensive and credible comparative toxicity assessments of PM and risk determinations associated with exposures to different air sheds can be expedited in a manner not previously possible. The simplicity of this approach may enable large scale assessments of PM samples with varying chemical composition, of individual components of PM, and mixtures of individual components. Moreover, chemical fractionation may allow identification of the most potent chemical classes and elucidation of common mechanisms of action of the most potent PM sources.

Description:

Exposure to fine particulate matter (PM) air pollution causes adverse cardiopulmonary outcomes. Yet the limited capacity to readily identify contributing PM sources and associated PM constituents in any given ambient air shed impedes risk assessment efforts. The health effects of PM have been attributed in part to its capacity to elicit irritant responses. A variety of chemicals trigger irritant behavior responses in zebrafish that can be easily measured. The purposes of this study were to examine the utility of zebrafish locomotor responses in the toxicity assessment of fine PM and its chemical fractions and uncover mechanisms of action. Locomotor responses were recorded in six day-old zebrafish exposed for 60 min in the dark at 26◦C to the extractable organic matter of a compressor-generated diesel exhaust PM (C-DEP) and four of its fractions (F1-F4) containing varying chemical classes of increasing polarity. The role of the transient receptor potential (TRP) cation channel TRPA1, a chemical sensor in mammals and zebrafish, in locomotor responses to C-DEP, was also examined. Acrolein, an environmental irritant and known activator of TRPA1, and all extracts induced concentration-dependent locomotor responses whose potencies ranked as follows: polar F3 > weakly polar F2 > C-DEP > highly polar F4 > non-polar F1, indicating that polar and weakly polar fractions that included nitro- and oxy-polyaromatic hydrocarbons (PAHs), drove C-DEP responses. Irritant potencies in fish positively correlated with mutagenic potencies of the same extracts in strains of Salmonella sensitive to nitro- and oxy-PAHs, further implicating these chemical classes in the zebrafish responses to C-DEP. Pharmacologic inhibition of TRPA1 blocked locomotor responses to acrolein and the extracts. Taken together, these data indicate that the zebrafish locomotor assay may help expedite toxicity screening of fine PM sources, identify causal chemical classes, and uncover plausible biological mechanisms.

URLs/Downloads:

Record Details: