title: MitoVitE, a mitochondria-targeted antioxidant, limits paclitaxel-induced oxidative stress and mitochondrial damage in vitro, and paclitaxel-induced mechanical hypersensitivity in a rat pain model.
abstract: BACKGROUND
  Neuropathic pain is a common side-effect of chemotherapy. Although precise mechanisms are unclear, oxidative stress and mitochondrial damage are involved. We investigated whether the mitochondria targeted antioxidant, MitoVitE, provided better protection against paclitaxel-induced mitochondrial damage in rat dorsal root ganglion (DRG) cells, than a non-targeted form of vitamin E, Trolox. We also determined whether MitoVitE, compared with duloxetine, could limit paclitaxel-induced mechanical hypersensitivity in rats.
  
  
  METHODS
  Mitochondrial function was measured in DRG cells exposed to paclitaxel with and without MitoVitE or Trolox. The effect of MitoVitE or Trolox on paclitaxel-induced cell killing in cancer cell lines was also determined. Rats received a cumulative dose of 8 mg kg-1paclitaxel plus either MitoVitE (2 mg-1kg day-1), duloxetine (10 mg kg-1day-1) or vehicle control daily. Mechanical hind paw withdrawal thresholds were measured every two days.
  
  
  RESULTS
  Paclitaxel caused loss of membrane potential in DRG cells. At 100 µM paclitaxel median [range] change was 61[44-78]%, P < 0.0001, which was ameliorated by MitoVitE (86[62-104]%) but not Trolox (46[46-57]%). Similarly, loss of metabolic activity and glutathione induced by paclitaxel (both P < 0.0001) were reduced by MitoVitE but not Trolox. Cytotoxicity of paclitaxel was not affected by co-exposure of ovarian cancer cells to either MitoVitE or Trolox, but was slightly reduced against breast cancer cells, in the presence of Trolox. Mean (SD) areas under the curve of withdrawal thresholds at 6 h after injection in rats given paclitaxel + control, or + MitoVitE (P < 0.0001) or + duloxetine (P < 0.0001) were 110 (5), 145 (10) and 156 (13) respectively.
  
  
  CONCLUSIONS
  Paclitaxel affected mitochondrial function and glutathione in DRG cells, which was abrogated by MitoVitE but not Trolox, without decreasing cancer cell cytotoxicity. In rats, paclitaxel-induced mechanical hypersensitivity was ameliorated by MitoVitE treatment to an extent similar to duloxetine. These data confirm mitochondria as a mechanistic target for paclitaxel-induced damage and suggest mitochondria targeted antioxidants as future therapeutic strategies.
authors: Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition University of Aberdeen, Aberdeen UK.|Centre for Integrative Physiology University of Edinburgh.
authors: B
authors: B
authors: McCormick
authors: Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition University of Aberdeen, Aberdeen UK.
authors: D A
authors: DA
authors: Lowes
authors: Department of Anaesthesia, Critical Care and Pain Medicine, University of Edinburgh, Edinburgh UK.
authors: L
authors: L
authors: Colvin
authors: Centre for Integrative Physiology University of Edinburgh h.f.galley@abdn.ac.uk carole.torsney@ed.ac.uk.
authors: C
authors: C
authors: Torsney
authors: Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition University of Aberdeen, Aberdeen UK h.f.galley@abdn.ac.uk carole.torsney@ed.ac.uk.
authors: H F
authors: HF
authors: Galley
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000009:adverse effects; D000975:Antioxidants / Q000494:pharmacology; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000517:prevention & control*; D066298:In Vitro Techniques; D008297:Male; D008928:Mitochondria / Q000187:drug effects*; D009437:Neuralgia / Q000517:prevention & control*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D017239:Paclitaxel / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014451:Ubiquinone / Q000494:pharmacology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; C478642:MitoVit E; D009943:Organophosphorus Compounds; D014451:Ubiquinone; D017239:Paclitaxel
keywords: Paclitaxel; mitochondria; pain