Iglesias-Gonzalez 2012 Neurochem Res

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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.

» PMID: 22821477

Iglesias-Gonzalez J, Sanchez-Iglesias S, Mendez-Alvarez E, Rose S, Hikima A, Jenner P, Soto-Otero R (2012) Neurochem Res

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:HRR: Oxygraph-2k 


Comments

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 [4].
  • 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].
  1. Gnaiger E, Steinlechner-Maran R, Méndez G, Eberl T, Margreiter R (1995) Control of mitochondrial and cellular respiration by oxygen. J Bioenerg Biomembr 27: 583-596.
  2. Gnaiger E (2001) Bioenergetics at low oxygen: dependence of respiration and phosphorylation on oxygen and adenosine diphosphate supply. Respir Physiol 128: 277-297.
  3. Gnaiger E (2008) Polarographic oxygen sensors, the oxygraph and high-resolution respirometry to assess mitochondrial function. In: Mitochondrial Dysfunction in Drug-Induced Toxicity (Dykens JA, Will Y, eds) John Wiley: 327-352.
  4. Kuznetsov AV, Gnaiger E. Oxygraph assay of cytochrome c oxidase activity: Chemical background correction. Mitochondr Physiol Network 06.06.
  5. Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41: 1837-1845.
  6. Gnaiger E (2012) Mitochondrial Pathways and Respiratory Control. An Introduction to OXPHOS Analysis. Mitochondr Physiol Network 17.18. Oroboros MiPNet Publications, Innsbruck: 64 pp.