Untargeted metabolomics of neuronal cell culture: A model system for the toxicity testing of insecticide chemical exposure

Abstract

Toxicity testing is essential for the protection of human health from exposure to toxic environmental chemicals. As traditional toxicity testing is carried out using animal models, mammalian cell culture models are becoming an increasingly attractive alternative to animal testing. Combining the use of mammalian cell culture models with screening-style molecular profiling technologies, such as metabolomics, can uncover previously unknown biochemical bases of toxicity. We have used a mass spectrometry-based untargeted metabolomics approach to characterize for the first time the changes in the metabolome of the B50 cell line, an immortalised rat neuronal cell line, following acute exposure to two known neurotoxic chemicals that are common environmental contaminants; the pyrethroid insecticide permethrin and the organophosphate insecticide malathion. B50 cells were exposed to either the dosing vehicle (methanol) or an acute dose of either permethrin or malathion for 6 and 24 hours. Intracellular metabolites were profiled by gas chromatography-mass spectrometry. Using principal components analysis, we selected the key metabolites whose abundance was altered by chemical exposure. By considering the major fold changes in abundance (>2.0 or <0.5 from control) across these metabolites, we were able to elucidate important cellular events associated with toxic exposure including disrupted energy metabolism and attempted protective mechanisms from excitotoxicity. Our findings illustrate the ability of mammalian cell culture metabolomics to detect finer metabolic effects of acute exposure to known toxic chemicals, and validate the need for further development of this process in the application of trace-level dose and chronic toxicity studies, and toxicity testing of unknown chemicals.

Untargeted Metabolomic Analysis of Rat Neuroblastoma Cells as a Model System to Study the Biochemical Effects of the Acute Administration of Methamphetamine

“…Such an approach, for the prediction of toxic effects on biochemical pathways, is not only essential for enhancing our understanding of toxicology, but is also essential for the reduction of the use of animals in toxic chemical testing. As previously advocated, a ‘whole of cell’ metabolomic approach has benefits over individual biomarkers derived from animal studies, because it allows changes across entire biochemical pathways to be profiled, giving a more complete picture of the effects of toxins [ 36 ]. Future studies should compare the metabolic effect of methamphetamine on a human neuronal cell line with that on the rat B50 neuronal cell line.…”

“…Very few studies have used this approach for the assessment of neurotoxicity [ 35 ]. We have recently demonstrated that gas chromatography–mass spectrometry (GC–MS) metabolomic analysis could be used to generate meaningful biochemical data about the effects of a high dose of insecticides on a continuous cell line, the rat B50 neuroblastoma [ 36 ]. The aim of this study was therefore to determine whether this same model could be applied to the study of methamphetamine toxicity, and to generate biologically relevant data.…”

Toxicometabolomics: Small Molecules to Answer Big Toxicological Questions

“…Some authors restrict the metabolome to the set of endogenous metabolites [ 6 , 7 , 8 ], although the exogenous metabolites (e.g., drugs and body microbiota) also play an important role in an organism’s physiology or pathophysiology [ 9 ]. In fact, the metabolome can be divided into four categories: (i) the intracellular metabolome (or endometabolome), which includes all metabolites produced by each cell type, tissue, or organism [ 10 , 11 ]; (ii) the extracellular metabolome (or exometabolome), which refers to the metabolites secreted or consumed by the cells [ 11 , 12 ]; (iii) the microbial metabolome produced by the microbiota [ 10 , 13 ]; and (iv) the xenometabolome, which includes the metabolites derived from xenobiotics, pollutants, and diet [ 10 , 14 ].…”