Energy status, ubiquitin proteasomal function, and oxidative stress during chronic and acute complex I inhibition with rotenone in mesencephalic cultures.
Complex I impairment with rotenone produces damage though a mechanism thought to be distinct from effects on mitochondrial respiration. The outcome of chronic rotenone on energy status in relation to toxicity, however, is unknown. To examine this, mesencephalic cultures were exposed to chronic, low-dose rotenone (5-100 nM, 8 days in vitro) or acute, high-dose rotenone (500 nM, 1-24 h), and ATP/ADP levels and toxicity were measured. Chronic exposure to 5-50 nM rotenone produced selective dopamine cell loss. High-dose rotenone produced nonselective damage at all exposure times. Chronic, low-dose rotenone (37.5 nM) decreased ATP/ADP gradually over several days to 40% of controls, whereas high-dose rotenone (500 nM, 1-6 h), collapsed ATP/ADP by 1 h of exposure. The ubiquitin proteasomal pathway, an ATP-dependent pathway, is implicated in Parkinson's disease and, thus, various rotenone exposures were examined for effects on ubiquitin proteasomal function. Chronic, low-dose rotenone (25-50 nM, 8 days), but not acute, high-dose rotenone (500 nM, 1-6 h), caused accumulation of ubiquitinated proteins, E1-ubiquitin activation, and increased proteasomal activities prior to toxicity even though both exposures increased free radical production. Findings show that selective dopamine cell loss and alterations in ubiquitin proteasomal function only occur with rotenone exposures that partially maintain ATP/ADP. High concentrations of rotenone that collapse energy status kill neurons in a nonselective manner independent of the ubiquitin proteasomal pathway.
Zeevalk
Gail D
GD
University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Department of Neurology, Piscataway, NJ 08854, USA. zeevalgd@umdnj.edu
Bernard
Laura P
LP
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism / Q000633:toxicity; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology; D008636:Mesencephalon / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008970:Molecular Weight; D018384:Oxidative Stress; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000633:toxicity
D017382:Reactive Oxygen Species; D025801:Ubiquitin; D012402:Rotenone; D005680:gamma-Aminobutyric Acid; D000255:Adenosine Triphosphate; D014446:Tyrosine 3-Monooxygenase; D046988:Proteasome Endopeptidase Complex; D010751:Phosphopyruvate Hydratase; D042967:Electron Transport Complex I; D005947:Glucose; D004298:Dopamine