TY - JOUR
T1 - Reactive species and oxidative stress in optic nerve vulnerable to secondary degeneration
AU - O'Hare Doig, Ryan L.
AU - Bartlett, Carole A.
AU - Maghzal, Ghassan J.
AU - Lam, Magdalena
AU - Archer, Michael
AU - Stocker, Roland
AU - Fitzgerald, Melinda
N1 - Funding Information:
We are grateful to Elora Bartlett and Conor McCarthy for technical assistance with mitochondrial quantification and Ivan Lozic for the schematic diagram. We acknowledge financial support from the Neurotrauma Research Program of Western Australia, an initiative of the Road Safety Council of Western Australia. This project is funded through the Road Trauma Trust Account, Western Australia, but does not reflect views or recommendations of the Road Safety Council. This work was partly supported by an Australian Research Council Discovery Project Grant DP 110102135 (to G.J.M.) and a National Health & Medical Research Council of Australia (NHMRC) Project Grant 1037879 (to R.S.). R.S. is supported by a NHMRC Senior Principal Research Fellowship.
PY - 2014/11
Y1 - 2014/11
N2 - Secondary degeneration contributes substantially to structural and functional deficits following traumatic injury to the CNS. While it has been proposed that oxidative stress is a feature of secondary degeneration, contributing reactive species and resultant oxidized products have not been clearly identified in vivo. The study is designed to identify contributors to, and consequences of, oxidative stress in a white matter tract vulnerable to secondary degeneration. Partial dorsal transection of the optic nerve (ON) was used to model secondary degeneration in ventral nerve unaffected by the primary injury. Reactive species were assessed using fluorescent labelling and liquid chromatography/tandem mass spectroscopy (LC/MS/MS). Antioxidant enzymes and oxidized products were semi-quantified immunohistochemically. Mitophagy was assessed by electron microscopy. Fluorescent indicators of reactive oxygen and/or nitrogen species increased at 1, 3 and 7. days after injury, in ventral ON. LC/MS/MS confirmed increases in reactive species linked to infiltrating microglia/macrophages in dorsal ON. Similarly, immunoreactivity for glutathione peroxidase and haem oxygenase-1 increased in ventral ON at 3 and 7. days after injury, respectively. Despite increased antioxidant immunoreactivity, DNA oxidation was evident from 1. day, lipid oxidation at 3. days, and protein nitration at 7. days after injury. Nitrosative and oxidative damage was particularly evident in CC1-positive oligodendrocytes, at times after injury at which structural abnormalities of the Node of Ranvier/paranode complex have been reported. The incidence of mitochondrial autophagic profiles was also significantly increased from 3. days. Despite modest increases in antioxidant enzymes, increased reactive species are accompanied by oxidative and nitrosative damage to DNA, lipid and protein, associated with increasing abnormal mitochondria, which together may contribute to the deficits of secondary degeneration.
AB - Secondary degeneration contributes substantially to structural and functional deficits following traumatic injury to the CNS. While it has been proposed that oxidative stress is a feature of secondary degeneration, contributing reactive species and resultant oxidized products have not been clearly identified in vivo. The study is designed to identify contributors to, and consequences of, oxidative stress in a white matter tract vulnerable to secondary degeneration. Partial dorsal transection of the optic nerve (ON) was used to model secondary degeneration in ventral nerve unaffected by the primary injury. Reactive species were assessed using fluorescent labelling and liquid chromatography/tandem mass spectroscopy (LC/MS/MS). Antioxidant enzymes and oxidized products were semi-quantified immunohistochemically. Mitophagy was assessed by electron microscopy. Fluorescent indicators of reactive oxygen and/or nitrogen species increased at 1, 3 and 7. days after injury, in ventral ON. LC/MS/MS confirmed increases in reactive species linked to infiltrating microglia/macrophages in dorsal ON. Similarly, immunoreactivity for glutathione peroxidase and haem oxygenase-1 increased in ventral ON at 3 and 7. days after injury, respectively. Despite increased antioxidant immunoreactivity, DNA oxidation was evident from 1. day, lipid oxidation at 3. days, and protein nitration at 7. days after injury. Nitrosative and oxidative damage was particularly evident in CC1-positive oligodendrocytes, at times after injury at which structural abnormalities of the Node of Ranvier/paranode complex have been reported. The incidence of mitochondrial autophagic profiles was also significantly increased from 3. days. Despite modest increases in antioxidant enzymes, increased reactive species are accompanied by oxidative and nitrosative damage to DNA, lipid and protein, associated with increasing abnormal mitochondria, which together may contribute to the deficits of secondary degeneration.
KW - Antioxidant enzymes
KW - Mitophagy
KW - Neurotrauma
KW - Oxidative damage
KW - Oxidative stress
KW - Reactive species
KW - Secondary degeneration
UR - http://www.scopus.com/inward/record.url?scp=84905222698&partnerID=8YFLogxK
U2 - 10.1016/j.expneurol.2014.06.007
DO - 10.1016/j.expneurol.2014.06.007
M3 - Article
C2 - 24931225
AN - SCOPUS:84905222698
SN - 0014-4886
VL - 261
SP - 136
EP - 146
JO - Experimental Neurology
JF - Experimental Neurology
ER -