title: Mitochondrial DNA damage as a peripheral biomarker for mitochondrial toxin exposure in rats.
abstract: Demonstrating or verifying a current or past exposure to an environmental mitochondrial toxin or toxicant is extraordinarily difficult. Thus, there is a pressing need to develop a biomarker for exposure to environmental mitochondrial inhibitors. Rotenone, an environmental toxicant, is a potent inhibitor of the mitochondrial electron transfer chain. Rotenone specifically inhibits complex I throughout the body and brain, thereby producing systemic mitochondrial impairment. As such, rotenone is a prototypical clinically relevant, environmental mitochondrial toxicant that may be used as an ideal initial platform to develop accessible biomarkers of exposure. The over-arching goal of this work is to explore and validate peripheral (blood and skeletal muscle) DNA damage as a biomarker of mitochondrial toxicant exposure using the rat rotenone model. In this effort, we utilized an extremely sensitive quantitative polymerase chain reaction (QPCR)-based assay that simultaneously allows the assessment of multiple forms of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) damage. We found mtDNA damage in blood is detected after subclinical rotenone exposure and the damage persists even after complex I activity has returned to normal. With a more sustained rotenone exposure, mtDNA damage is also detected in skeletal muscle, suggesting that mtDNA damage in this tissue simply lags behind blood. Using the QPCR-based assay, we have no evidence for nDNA damage in peripheral tissues after rotenone exposure either acutely or chronically. Overall, these data support the idea that mtDNA damage in peripheral tissues in the rotenone model may provide a biomarker of past or ongoing mitochondrial toxin exposure.
authors.affiliation: Pittsburgh Institute for Neurodegenerative Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15260 lhs5@pitt.edu.
authors.forename: Laurie H
authors.initials: LH
authors.lastname: Sanders
authors.affiliation: Pittsburgh Institute for Neurodegenerative Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: Evan H
authors.initials: EH
authors.lastname: Howlett
authors.affiliation: Pittsburgh Institute for Neurodegenerative Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: Jennifer
authors.initials: J
authors.lastname: McCoy
authors.affiliation: Pittsburgh Institute for Neurodegenerative Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15260 lhs5@pitt.edu.
authors.forename: J Timothy
authors.initials: JT
authors.lastname: Greenamyre
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D004249:DNA Damage / Q000187:drug effects*; D004272:DNA, Mitochondrial / Q000097:blood / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D011917:Rats, Inbred Lew; D060888:Real-Time Polymerase Chain Reaction; D012402:Rotenone / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D004272:DNA, Mitochondrial; D012402:Rotenone
keywords: DNA damage; biomarkers; mitochondrial toxins; pesticides; rotenone