title: iNOS-mediated secondary inflammatory response differs between rat strains following experimental brain contusion.
abstract: BACKGROUND
  Nitric oxide is a key mediator of post-traumatic inflammation in the brain. We examined the expressions of iNOS, nNOS, and eNOS in inbred DA and PVGa rat strains where DA is susceptible to autoimmune neuroinflammation and PVGa-resistant.
  
  
  METHODS
  Parietal contusions using a weight drop model were produced in five rats per genotype. After 24 h, the brains were removed and analyzed using a range of immunohistochemical methods.
  
  
  RESULTS
  PVGa presented significantly increased iNOS expression in infiltrating inflammatory cells in the perilesional area compared to DA (p < 0.05). The amount of w3/13-positive infiltrating inflammatory cells did not differ between strains. eNOS and nNOS expression did not differ between strains. iNOS-positive cells coexpressed neuronal (NeuN), macrophage (ED-1), and leucocyte (w3/13) markers. MnSOD was significantly increased in PVGa (p < 0.05). 3-Nitrotyrosine, a measure of peroxynitrite levels, and fluoro-jade stained neuronal degeneration, did not differ between strains.
  
  
  CONCLUSIONS
  Two inbred rat strains with genetically determined differences in susceptibility to develop autoimmune disease displayed different levels of the inflammatory and anti-inflammatory mediators iNOS and MnSOD, indicating genetic regulation. Interestingly, the increased levels of iNOS did not lead to elevated expression of the neuronal cell-death marker fluoro-jade. The increased iNOS expression was correlated with increased expression of superoxide scavenger MnSOD. Excessive peroxynitrite formation was probably prevented by limitation of available superoxide. Subsequently, the higher expression of potentially deleterious iNOS in PVGa did not result in increased neuronal death.
authors.affiliation: Department of Clinical Neuroscience, Section of Neurosurgery and Neuroimmunology, Karolinska Institutet, Stockholm, Sweden. mattias.gunther@ki.se
authors.forename: Mattias
authors.initials: M
authors.lastname: Günther
authors.forename: Faiez
authors.initials: F
authors.lastname: Al Nimer
authors.forename: Caroline
authors.initials: C
authors.lastname: Gahm
authors.forename: Fredrik
authors.initials: F
authors.lastname: Piehl
authors.forename: Tiit
authors.initials: T
authors.lastname: Mathiesen
mesh_terms: D000818:Animals; D001930:Brain Injuries / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D004195:Disease Models, Animal; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D007249:Inflammation / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013045:Species Specificity
chemical_list: D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat