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Development of in vitro screening assays for potentially neurotoxic polyaromatic hydrocarbons in SY5Y and C6 cells
Polycyclic aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons (HAHs) are ubiquitous in the environment. Some congeners produce extreme toxicity in laboratory Animal studies. While much attention has been given to the carcinogenicity, little work has been done in neurotoxicology. Therefore, the focus of this thesis was to analyze neurotoxicity by these measurements of cytotoxicity in neuronal and goal 11 lines. Amino acid incorporation into proteins, total protein, trypan blue dye exclusion and total cell count were measured as indicators of cytotoxicity. In addition acetycholinesterase (ACM) activity was measured as a direct indicator of neurotoxicity. Cells were exposed to three model PAHs, benzo(a)pyrene (BAP), cosine, and anthracene, and one model HAH, pentachlorophenol (PCP). Neurotoxicity of individual PAHs and PCP was compared with mixtures of PAHs and PCP. In this thesis SY5Y and C6 cell lines were used. The test concentrations of each PAH and PCP were 0.03, 0.3, 3. 30 M. BAP showed the highest mycotoxic of the compounds tested. At a dose of 3 M or 30 M, BAP produced a significant mycotoxic response in SY5Y cells. SY5Y cells teated with cosine, anthracene, and PCP showed no significant effects compared to controls. C6 cells appeared to be less sensitive to the cytotoxicity then SY5Y cells. This finding may reject the lower level of P450 activity compared with SY5Y cells. S9 liver extras, which possesses high P450 activity, was used to enhance metabolism of PAHs. In most cases, the individual PAHs were inactive in C6 cells without agitation, while cytotoxicity was increased following S9 metabolism. In the present study, the rank order of neurotoxicity was BAP > chrysene > anthracene. In SY5Y cells, mixtures of BAP and chrysene or BAP and PCP exhibited the same degree of cytotoxicity as did the individual chemicals. However, in C6 cells the mixture of 3 M BAP and 3 M chrysene induced a more mycotoxic response than at same concentration of individual compounds. PCP at 3M alone significantly inhibited AChE activity in SY5Y cells, but BAP and chrysene had no effect. Furthermore, binary mixtures of PCP with mipafox together produced a significant increase in inhibition of AChE. These data suggest that co- exposure to PCP and organophosphates may result in a chemical interaction that increases the relative toxic response.
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Includes bibliographical references (leaves 54-63).
Issued also on microfiche from Lange Micrographics.
Tang, Yan (1999). Development of in vitro screening assays for potentially neurotoxic polyaromatic hydrocarbons in SY5Y and C6 cells. Master's thesis, Texas A&M University. Available electronically from
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