Blockade of the MEK/ERK pathway with a raf inhibitor prevents activation of pro-inflammatory mediators in cerebral arteries and reduction in cerebral blood flow after subarachnoid hemorrhage in a rat model.
Cerebral ischemia that develops after subarachnoid hemorrhage (SAH) carries high morbidity and mortality. Inflammatory mediators are involved in the development of cerebral ischemia through activation of the mitogen-activated protein kinase pathway. We hypothesized that blockade of the MAPkinase/ERK (MEK)/extracellular signal-regulated kinase (ERK) pathway upstream with a specific raf inhibitor would prevent SAH-induced activation of the cerebrovascular inflammatory response. The raf inhibitor SB-386023-b was injected intracisternally in our rat model at 0, 6, or 12 hours after the SAH. After 48 hours, cerebral arteries were harvested, and iNOS, interleukin (IL)-6, IL-1β, matrix metalloproteinase (MMP)-9, tissue inhibitors of metalloproteinase (TIMP)-1, and phosphorylated ERK1/2 were investigated by immunofluorescence, real-time polymerase chain reaction (PCR), and Western blot analysis. Cerebral blood flow (CBF) was measured using autoradiography. Protein levels of MMP-9, TIMP-1, iNOS, IL-6, and IL-1β were increased after SAH, as were mRNA levels of IL-6, MMP-9, and TIMP-1. After SAH, pERK1/2 was increased, but CBF was reduced. Treatment with SB-386023-b at 0 or 6 hours after SAH normalized CBF and prevented SAH-induced upregulation of MMPs, pro-inflammatory cytokines, and pERK1/2 proteins. These results suggested that inhibition of MEK/ERK signal transduction by a specific raf inhibitor administered up to 6 hours after SAH normalized the expression of pro-inflammatory mediators and extracellular matrix-related genes.
Maddahi
Aida
A
Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Lund, Sweden.
Ansar
Saema
S
Chen
Qingwen
Q
Edvinsson
Lars
L
D000199:Actins / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D015153:Blotting, Western; D002536:Cerebral Arteries / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D019084:Fluorescent Antibody Technique, Indirect; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000502:physiology*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D013345:Subarachnoid Hemorrhage / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology*; D048490:raf Kinases / Q000037:antagonists & inhibitors*
D000199:Actins; D018836:Inflammation Mediators; D012313:RNA; D048490:raf Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases