title: Alterations in mitochondrial dynamics induced by tebufenpyrad and pyridaben in a dopaminergic neuronal cell culture model.
abstract: Tebufenpyrad and pyridaben are two agro-chemically important acaricides that function like the known mitochondrial toxicant rotenone. Although these two compounds have been commonly used to kill populations of mites and ticks in commercial greenhouses, their neurotoxic profiles remain largely unknown. Therefore, we investigated the effects of these two pesticides on mitochondrial structure and function in an in vitro cell culture model using the Seahorse bioanalyzer and confocal fluorescence imaging. The effects were compared with rotenone. Exposing rat dopaminergic neuronal cells (N27 cells) to tebufenpyrad and pyridaben for 3h induced dose-dependent cell death with an EC50 of 3.98μM and 3.77μM, respectively. Also, tebufenpyrad and pyridaben (3μM) exposure induced reactive oxygen species (ROS) generation and m-aconitase damage, suggesting that the pesticide toxicity is associated with oxidative damage. Morphometric image analysis with the MitoTracker red fluorescent probe indicated that tebufenpyrad and pyridaben, as well as rotenone, caused abnormalities in mitochondrial morphology, including reduced mitochondrial length and circularity. Functional bioenergetic experiments using the Seahorse XF96 analyzer revealed that tebufenpyrad and pyridaben very rapidly suppressed the basal mitochondrial oxygen consumption rate similar to that of rotenone. Further analysis of bioenergetic curves also revealed dose-dependent decreases in ATP-linked respiration and respiratory capacity. The luminescence-based ATP measurement further confirmed that pesticide-induced mitochondrial inhibition of respiration is accompanied by the loss of cellular ATP. Collectively, our results suggest that exposure to the pesticides tebufenpyrad and pyridaben induces neurotoxicity by rapidly initiating mitochondrial dysfunction and oxidative damage in dopaminergic neuronal cells. Our findings also reveal that monitoring the kinetics of mitochondrial respiration with Seahorse could be used as an early neurotoxicological high-throughput index for assessing the risk that pesticides pose to the dopaminergic neuronal system.
authors.affiliation: Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
authors.forename: Adhithiya
authors.initials: A
authors.lastname: Charli
authors.affiliation: Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
authors.forename: Huajun
authors.initials: H
authors.lastname: Jin
authors.affiliation: Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
authors.forename: Vellareddy
authors.initials: V
authors.lastname: Anantharam
authors.affiliation: Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States.
authors.forename: Arthi
authors.initials: A
authors.lastname: Kanthasamy
authors.affiliation: Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, United States. Electronic address: akanthas@iastate.edu.
authors.forename: Anumantha G
authors.initials: AG
authors.lastname: Kanthasamy
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002461:Cell Line, Transformed; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000648:ultrastructure*; D004305:Dose-Response Relationship, Drug; D063154:Mitochondrial Dynamics / Q000187:drug effects*; D009498:Neurotoxins / Q000633:toxicity*; D010101:Oxygen Consumption / Q000187:drug effects; D011720:Pyrazoles / Q000633:toxicity*; D011724:Pyridazines / Q000633:toxicity*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D009498:Neurotoxins; D011720:Pyrazoles; D011724:Pyridazines; D017382:Reactive Oxygen Species; C429623:4-chloro-N-((4-(1,1-dimethylethyl)phenyl)methyl)-3-ethyl-1-methyl-1H-pyrazole-5-carboxamide; C428725:pyridaben; D000255:Adenosine Triphosphate; D000154:Aconitate Hydratase
keywords: Mitochondrial dysfunction; Neurotoxicity; Oxidative stress; Pesticides; Pyridaben; Seahorse; Tebufenpyrad