Iglesias-Gonzalez 2012 Neurochem Res
|Iglesias-Gonzalez J, Sanchez-Iglesias S, Mendez-Alvarez E, Rose S, Hikima A, Jenner P, Soto-Otero R (2012) Differential toxicity of 6-hydroxydopamine in SH-SY5Y human neuroblastoma cells and rat brain mitochondria: protective role of catalase and superoxide dismutase. Neurochem Res 37:2150-60.|
Abstract: Oxidative stress and mitochondrial dysfunction are two pathophysiological factors often associated with the neurodegenerative process involved in Parkinson's disease (PD). Although, 6-hydroxydopamine (6-OHDA) is able to cause dopaminergic neurodegeneration in experimental models of PD by an oxidative stress-mediated process, the underlying molecular mechanism remains unclear. It has been established that some antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) are often altered in PD, which suggests a potential role of these enzymes in the onset and/or development of this multifactorial syndrome. In this study we have used high-resolution respirometry to evaluate the effect of 6-OHDA on mitochondrial respiration of isolated rat brain mitochondria and the lactate dehydrogenase cytotoxicity assay to assess the percentage of cell death induced by 6-OHDA in human neuroblastoma cell line SH-SY5Y. Our results show that 6-OHDA affects mitochondrial respiration by causing a reduction in both respiratory control ratio (IC(50) = 200 ± 15 nM) and State 3 respiration (IC(50) = 192 ± 17 nM), with no significant effects on State 4(o). An inhibition in the activity of both Complex I and V was also observed. 6-OHDA also caused cellular death in human neuroblastoma SH-SY5Y cells (IC(50) = 100 ± 9 μM). Both SOD and CAT have been shown to protect against the toxic effects caused by 6-OHDA on mitochondrial respiration. However, whereas SOD protects against 6-OHDA-induced cellular death, CAT enhances its cytotoxicity. The here reported data suggest that both superoxide anion and hydroperoxyl radical could account for 6-OHDA toxicity. Furthermore, factors reducing the rate of 6-OHDA autoxidation to its p-quinone appear to enhance its cytotoxicity.
• Keywords: Parkinson's disease, 6-hydroxydopamine (6-OHDA)
• O2k-Network Lab: ES Santiago De Compostela Mendez-Alvarez E
Labels: MiParea: Respiration Pathology: Neurodegenerative, Parkinson's Stress:Oxidative stress;RONS, Mitochondrial disease Organism: Rat Tissue;cell: Nervous system Preparation: Isolated mitochondria Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase
Coupling state: LEAK, OXPHOS, ET Pathway: N HRR: Oxygraph-2k
by Erich Gnaiger (2013-01-31)
- "The rate of oxygen consumption before addition of mitochondria was subtracted from all measurements." - We do not recommend to perform this correction: The instrumental background is not constant over the experimental oxygen range, since (i) oxygen consumption of the sensor is clearly dependent on partial pressure of oxygen and therefore declines with declining oxygen concentration, and (ii) a small oxygen backdiffusion is observed with declining experimental oxygen levels, which further reduces the initial oxygen consumption measured at air saturation in the absence of biological material. The instrumental background correction in high-resolution respirometry, therefore, takes into account the oxygen dependence and DatLab automatically includes this correction [1-3]. Autoxidation reactions typically are oxygen dependent over the entire range from anoxia to hyperoxia, and the oxygen-dependent correction should then be applied for both the instrumental and chemical component of the total background oxygen consumption .
- Complex V was most severely inactivated. The low RCR (high L/P ratio), therefore, might not indicate a lower coupling state, but a lower phosphorylation capacity, in which case the L/E ratio (LEAK/ET capacity) would provide information on the coupling state [5,6].
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