Blockade of the extracellular signal-regulated kinase pathway by U0126 attenuates neuronal damage following circulatory arrest.
OBJECTIVE
The extracellular signal-regulated kinase pathway of the mitogen-activated protein kinase signal transduction cascade has been implicated in the neuronal and endothelial dysfunction witnessed following cerebral ischemia-reperfusion injury. Extracellular signal-regulated kinase is activated by mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2. We evaluated the ability of a mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2-specific inhibitor (U0126) to block extracellular signal-regulated kinase activation and mitigate ischemic neuronal damage in a model of deep hypothermic circulatory arrest.


METHODS
Piglets underwent normal flow cardiopulmonary bypass (control, n = 4), deep hypothermic circulatory arrest (n = 6), and deep hypothermic circulatory arrest with U0126 (n = 5) at 20 degrees C for 60 minutes. The deep hypothermic circulatory arrest with U0126 group was given 200 microg/kg of U0126 45 minutes prior to initiation of bypass followed by 100 microg/kg at reperfusion. Following 24 hours of post-cardiopulmonary bypass recovery, brains were harvested. Eleven distinct cortical regions were evaluated for neuronal damage using hematoxylin and eosin staining. A section of ischemic cortex was further evaluated by immunohistochemistry with rabbit polyclonal antibody against phosphorylated extracellular signal-regulated kinase 1/2.


RESULTS
The deep hypothermic circulatory arrest and deep hypothermic circulatory arrest with U0126 groups displayed diffuse ischemic changes. However, the deep hypothermic circulatory arrest with U0126 group possessed significantly lower neuronal damage scores in the right frontal watershed zone of cerebral cortex, basal ganglia, and thalamus (P < or =.05) and an overall trend toward neuroprotection versus the deep hypothermic circulatory arrest group. This neuroprotection was accompanied by nearly complete blockade of phosphorylated extracellular signal-regulated kinase in the cerebral vascular endothelium.


CONCLUSIONS
In this experimental model of deep hypothermic circulatory arrest, U0126 blocked extracellular signal-regulated kinase activation and provided a significant neuroprotective effect. These results support targeting of the extracellular signal-regulated kinase pathway for inhibition as a novel therapeutic approach to mitigate neuronal damage following deep hypothermic circulatory arrest.
Cho
Deog-Gon
DG
Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Mulloy
Matthew R
MR
Chang
Paul A
PA
Johnson
Mahlon D
MD
Aharon
Alon S
AS
Robison
Trevor A
TA
Buckles
Tamara L
TL
Byrne
Daniel W
DW
Drinkwater
Davis C
DC
D000818:Animals; D000831:Animals, Newborn; D002545:Brain Ischemia / Q000201:enzymology* / Q000209:etiology*; D002070:Butadienes / Q000037:antagonists & inhibitors*; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006324:Heart Arrest, Induced; D007036:Hypothermia, Induced; D007150:Immunohistochemistry; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D008955:Models, Cardiovascular; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology*; D009570:Nitriles / Q000037:antagonists & inhibitors*; D011183:Postoperative Complications / Q000201:enzymology* / Q000209:etiology*; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D016896:Treatment Outcome
D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases