title: Regulation of enhanced cerebrovascular expression of proinflammatory mediators in experimental subarachnoid hemorrhage via the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway.
abstract: BACKGROUND
  Subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality. It is suggested that the associated inflammation is mediated through activation of the mitogen-activated protein kinase (MAPK) pathway which plays a crucial role in the pathogenesis of delayed cerebral ischemia after SAH. The aim of this study was first to investigate the timecourse of altered expression of proinflammatory cytokines and matrix metalloproteinase in the cerebral arteries walls following SAH. Secondly, we investigated whether administration of a specific mitogen-activated protein kinase kinase (MEK)1/2 inhibitor, U0126, given at 6 h after SAH prevents activation of the MEK/extracellular signal-regulated kinase 1/2 pathway and the upregulation of cerebrovascular inflammatory mediators and improves neurological function.
  
  
  METHODS
  SAH was induced in rats by injection of 250 μl of autologous blood into basal cisterns. U0126 was given intracisternally using two treatment regimens: (A) treatments at 6, 12, 24 and 36 h after SAH and experiments terminated at 48 h after SAH, or (B) treatments at 6, 12, and 24 h after SAH and terminated at 72 h after SAH. Cerebral arteries were harvested and interleukin (IL)-6, IL-1β, tumor necrosis factor α (TNF)α, matrix metalloproteinase (MMP)-9 and phosphorylated ERK1/2 (pERK1/2) levels investigated by immunohistochemistry. Early activation of pERK1/2 was measured by western blot. Functional neurological outcome after SAH was also analyzed.
  
  
  RESULTS
  Expression levels of IL-1β, IL-6, MMP-9 and pERK1/2 proteins were elevated over time with an early increase at around 6 h and a late peak at 48 to 72 h post-SAH in cerebral arteries. Enhanced expression of TNFα in cerebral arteries started at 24 h and increased until 96 h. In addition, SAH induced sensorimotor and spontaneous behavior deficits in the animals. Treatment with U0126 starting at 6 h after SAH prevented activation of MEK-ERK1/2 signaling. Further, U0126 significantly decreased the upregulation of inflammation proteins at 48 and 72 h following SAH and improved neurological function. We found no differences between treatment regimens A and B.
  
  
  CONCLUSIONS
  These results show that SAH induces early activation of the MEK-ERK1/2 pathway in cerebral artery walls, which is associated with upregulation of proinflammatory cytokines and MMP-9. Inhibition of the MEK-ERK1/2 pathway by U0126 starting at 6 h post-SAH prevented upregulation of cytokines and MMP-9 in cerebral vessels, and improved neurological outcome.
authors.affiliation: Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden. aida.maddahi@med.lu.se
authors.forename: Aida
authors.initials: A
authors.lastname: Maddahi
authors.forename: Gro Klitgaard
authors.initials: GK
authors.lastname: Povlsen
authors.forename: Lars
authors.initials: L
authors.lastname: Edvinsson
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology; D001804:Blood Transfusion, Autologous / Q000009:adverse effects; D002070:Butadienes / Q000627:therapeutic use; D002536:Cerebral Arteries / Q000201:enzymology* / Q000473:pathology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005106:Exploratory Behavior / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009043:Motor Activity / Q000187:drug effects; D009422:Nervous System Diseases / Q000188:drug therapy / Q000209:etiology; D009570:Nitriles / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D018709:Statistics, Nonparametric; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D002070:Butadienes; D016207:Cytokines; D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; D009570:Nitriles; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9