Trichloroethylene induces dopaminergic neurodegeneration in Fisher 344 rats.
Trichloroethylene, a chlorinated solvent widely used as a degreasing agent, is a common environmental contaminant. Emerging evidence suggests that chronic exposure to trichloroethylene may contribute to the development of Parkinson's disease. The purpose of this study was to determine if selective loss of nigrostriatal dopaminergic neurons could be reproduced by systemic exposure of adult Fisher 344 rats to trichloroethylene. In our experiments, oral administration of trichloroethylene induced a significant loss of dopaminergic neurons in the substantia nigra pars compacta in a dose-dependent manner, whereas the number of both cholinergic and GABAergic neurons were not decreased in the striatum. There was a robust decline in striatal levels of 3, 4-dihydroxyphenylacetic acid without a significant depletion of striatal dopamine. Rats treated with trichloroethylene showed defects in rotarod behavior test. We also found a significantly reduced mitochondrial complex I activity with elevated oxidative stress markers and activated microglia in the nigral area. In addition, we observed intracellular alpha-synuclein accumulation in the dorsal motor nucleus of the vagus nerve, with some in nigral neurons, but little in neurons of cerebral cortex. Overall, our animal model exhibits some important features of Parkinsonism, and further supports that trichloroethylene may be an environmental risk factors for Parkinson's disease.
Liu
Mei
M
Department of Anatomy and Neurobiology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA.
Choi
Dong-Young
DY
Hunter
Randy L
RL
Pandya
Jignesh D
JD
Cass
Wayne A
WA
Sullivan
Patrick G
PG
Kim
Hyoung-Chun
HC
Gash
Don M
DM
Bing
Guoying
G
D000818:Animals; D039481:CD11b Antigen / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry / Q000379:methods; D004660:Encephalitis / Q000139:chemically induced; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D008928:Mitochondria / Q000187:drug effects; D019636:Neurodegenerative Diseases / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D045442:Rotarod Performance Test; D012997:Solvents / Q000633:toxicity*; D013378:Substantia Nigra / Q000378:metabolism* / Q000473:pathology; D014241:Trichloroethylene / Q000633:toxicity*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D051844:alpha-Synuclein / Q000378:metabolism
D039481:CD11b Antigen; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D012997:Solvents; D051844:alpha-Synuclein; D014241:Trichloroethylene; C002744:3-nitrotyrosine; D014443:Tyrosine; D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase; D053148:Caspase 3; D004298:Dopamine