title: Peroxynitrite generated in the rat spinal cord induces neuron death and neurological deficits.
abstract: We previously demonstrated that the concentration of peroxynitrite significantly increases following impact spinal cord injury (SCI). The aim of this study was to test whether the SCI-induced elevation of peroxynitrite induces neuronal death and consequent neurological deficits. Peroxynitrite was generated by administering 5 mM S-morpholinosydnonimine, a donor of peroxynitrite, through a microdialysis fiber into the gray matter of the rat spinal cord for 5 h. This mimics the concentration and duration of peroxynitrite elevation after SCI. Neuron death was assessed by counting the neurons along the fiber track in Cresyl Violet-stained sections removed at different times post-peroxynitrite exposure. Peroxynitrite induced significantly more neuron death than did the artificial cerebrospinal fluid (ACSF) control, with the percentage of neuronal loss being 17+/-2%, 28+/-2%, 39+/-3%, and 43+/-4% at 6, 12, 24 and 48 h post-peroxynitrite exposure (P=0.01-<0.001). The losses of total neurons or motoneurons immuno-stained with anti-neuron-specific enolase or anti-choline acetyltransferase antibodies was significantly higher in the peroxynitrate-exposed group than in ACSF controls at 24 h post-exposure, further confirming peroxynitrate damage to neurons. The susceptibility to oxidative damage in motoneurons was similar to that of other neurons characterized at 24 h post-peroxynitrite exposure. Peroxynitrite-induced neurological deficits were examined by the Basso-Beattie-Bresnahan test (BBB test), the inclined-plane test and footprint analysis. Peroxynitrite significantly (P<0.001) reduced the locomotor rating score (BBB test) and the maximum angle of inclined plane compared to sham and ACSF-exposed animals (repeated measures analysis of variance). The footprint analysis revealed that peroxynitrite significantly increased the distance between the feet and the angle of hindlimb rotation compared to sham (P=0.01 and P<0.001) or ACSF controls (P=0.01 and P=0.005) and significantly shortened the stride length compared to sham (P<0.001) and ACSF control (P=0.005) treatments. Therefore the SCI-produced level of peroxynitrite induced neuron loss and neurological dysfunction, strong evidence that peroxynitrite is a secondary damage agent in SCI.
authors.affiliation: Department of Neurology, University of Texas Medical Branch, 301 University Boulevard RT 0653, Galveston, TX 77555-0653, USA.
authors.forename: F
authors.initials: F
authors.lastname: Bao
authors.forename: D
authors.initials: D
authors.lastname: Liu
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D004409:Dyskinesia, Drug-Induced / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008297:Male; D017551:Microdialysis; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D030421:Peroxynitrous Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
chemical_list: D020030:Nitric Oxide Donors; D030421:Peroxynitrous Acid; C002385:linsidomine; D008981:Molsidomine