ARB Research Seminar

This page updated March 26, 2019

Effects of Ultrafine Particulate Matter Exposure in an Animal Model of Neurodegenerative Disease

Photo of Arthur K. Cho, Ph.D.

Arthur K. Cho, Ph.D., University of California, Los Angeles

April 03, 2019
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


This study was designed to test the hypothesis that reactive components of ambient air collected at Irvine, in Southern California, could induce development of Parkinson's disease (PD)-like behavioral and neurochemical pathology in wild type mice (WT) and transgenic mice that express human alpha synuclein (ha-Syn) a marker protein for the disease. The mice were exposed to VACES-generated concentrated ultrafine particulate matter (UFPM) of <0.18 microns or filtered air for 22 weeks (5h/d; 4d/wk). The mice were then subjected to motor and cognitive behavioral tests, followed by brain assessments of inflammatory and neurochemical markers in striatum and hippocampus. Deficits in motor performance were observed in both WT and ha-Syn mice but without changes in the brain assessments. In parallel to the VACES collections, particulate matter of <2.5 microns (PM2.5) were collected by a Tisch sampler for quantitative analysis of their chemical reactivities and for cellular toxicity measurements. Comparisons with PM from those collected from other Los Angeles Basin (LAB) sites indicated that Irvine PM2.5 contained significant levels of organic prooxidants whereas those from the other sites had negligible levels of organic prooxidants. Furthermore, the total prooxidant content of the samples were lower than the levels found in other samples capable of inducing an inflammatory response following exposure to a mouse macrophage cell line. Thus, although the exposure protocols and in vivo response assessment were appropriate to test the hypothesis, the chemical reactivities of the ambient air appear to have been too weak to elicit a positive in vivo response. The results did demonstrate the value of monitoring the chemical properties of air pollution and performing analyses to characterize AP content in parallel with in vivo exposure studies, for they allow design of predictive studies with useful parameters.

Speaker Biography

Arthur K. Cho, Ph.D., is emeritus professor of Molecular and Medical Pharmacology and Environmental Health Sciences at UCLA Center for the Health Sciences. His research has focused on the relationship between chemical properties and the biological effects of xenobiotics, including compounds related to the amphetamines and quinones. His laboratory determined quinone concentrations in ambient air and examined their chemical and biological effects relevant to air pollution toxicology. These studies led to the development of chemically based assays for reactive chemical species in air samples which have been employed in this study together with biological assays to characterize the air samples. He has a B.S. (UC Berkeley), M.S. (Oregon State University) and a Ph.D. (UCLA) in chemistry. His co-investigators were Michael Kleinman, Ph.D., Professor of Medicine from UCI whose specialty is whole animal air pollution exposure and William Melega, Ph.D., Professor of Pharmacology from UCLA whose specialty is neurotoxicology.

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