title: Expression of nitric oxide synthase isoforms and nitrotyrosine formation after hypoxia-ischemia in the neonatal rat brain.
abstract: OBJECTIVE
  Production of nitric oxide is thought to play an important role in neuroinflammation. Previously, we have shown that combined inhibition of neuronal nitric oxide synthase (nNOS) and inducible NOS (iNOS) can reduce hypoxia-ischemia-induced brain injury in 12-day-old rats. The aim of this study was to analyze changes in expression of nNOS, iNOS and endothelial NOS (eNOS), and nitrotyrosine (NT) formation in proteins in neonatal rats up to 48 h after cerebral hypoxia-ischemia.
  
  
  METHODS
  Twelve-day-old rats were subjected to unilateral carotid artery occlusion and hypoxia, resulting in unilateral cerebral damage. NOS and nitrotyrosine expression were determined by immunohistochemistry and Western blot analysis at 30 min-48 h after hypoxia-ischemia.
  
  
  RESULTS
  nNOS was increased in both hemispheres from 30 min to 3 h after hypoxia-ischemia. In the contralateral hemisphere, eNOS was decreased 1-3 h after hypoxia-ischemia. In the ipsilateral hemisphere, eNOS was decreased at 0.5 h after hypoxia-ischemia, normalized at 1-3 h and was increased 6-12 h after hypoxia-ischemia. At 24 and 48 h after hypoxia-ischemia, eNOS levels normalized. Surprisingly, iNOS expression did not change from 30 min up to 48 h after hypoxia-ischemia in the ipsi- or contralateral hemisphere. In addition, the regional expression of iNOS in the brain as determined by immunohistochemistry did not change after hypoxia-ischemia. Expression of nitrotyrosine was slightly increased in both hemispheres only at 30 min after hypoxia-ischemia.
  
  
  CONCLUSIONS
  In 12-day-old rat pups, cerebral hypoxia-ischemia induced a transient increase in nNOS, eNOS, and nitrotyrosine in proteins, but no change in iNOS expression up to 48 h after the insult.
authors.affiliation: Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Evelyn R W
authors.initials: ER
authors.lastname: van den Tweel
authors.forename: Cora
authors.initials: C
authors.lastname: Nijboer
authors.forename: Annemieke
authors.initials: A
authors.lastname: Kavelaars
authors.forename: Cobi J
authors.initials: CJ
authors.lastname: Heijnen
authors.forename: Floris
authors.initials: F
authors.lastname: Groenendaal
authors.forename: Frank
authors.initials: F
authors.lastname: van Bel
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D004195:Disease Models, Animal; D005260:Female; D007839:Functional Laterality; D005786:Gene Expression Regulation / Q000502:physiology*; D020925:Hypoxia-Ischemia, Brain / Q000201:enzymology* / Q000473:pathology; D050112:Imino Pyranoses / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010880:Piperidines / Q000378:metabolism; D051381:Rats; D018709:Statistics, Nonparametric; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D050112:Imino Pyranoses; D010880:Piperidines; C098432:isofagomine; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase