Adrenomedullin gene delivery protects against cerebral ischemic injury by promoting astrocyte migration and survival.
Adrenomedullin (AM) has been shown to protect against ischemia/reperfusion-induced myocardial infarction and apoptosis. In the present study, we examined the potential neuroprotective action of delayed AM gene transfer in cerebral ischemia. Three days after a 1-hr occlusion of the middle cerebral artery (MCAO), rats were injected intravenously with adenovirus harboring human AM cDNA. The experiment was terminated 7 days after MCAO. AM gene transfer significantly reduced cerebral infarct size compared with that of rats before virus injection and compared with that of rats injected with control virus. The expression of recombinant human AM was identified in ischemic brain by immunostaining. Morphological analyses showed that AM gene transfer enhanced the survival and migration of astrocytes into the ischemic core. Cerebral ischemia markedly increased astrocyte apoptosis, and AM gene delivery significantly reduced apoptosis to near normal levels as seen in sham control rats. Similarly, in primary cultured astrocytes, AM stimulated cell migration and inhibited hypoxia/reoxygenation-induced apoptosis. The effects of AM on both migration and apoptosis were abolished by calcitonin gene-related peptide [CGRP(8-37)], an AM receptor antagonist. Enhanced cell survival after AM gene transfer was accompanied by markedly increased cerebral nitric oxide and Bcl-2 levels, as well as Akt and GSK-3beta phosphorylation, but reduced NADPH oxidase activity and superoxide production. Inactivation of GSK-3beta by phosphorylation led to reduced GSK-3beta activity and caspase- 3 activation. These results indicate that exogenous AM provides neuroprotection against cerebral ischemia injury by enhancing astrocyte survival and migration and inhibiting apoptosis through suppression of oxidative stress-mediated signaling events.
Xia
Chun-Fang
CF
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
Yin
Hang
H
Borlongan
Cesar V
CV
Chao
Julie
J
Chao
Lee
L
D053607:Adrenomedullin; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001253:Astrocytes / Q000166:cytology* / Q000502:physiology; D002545:Brain Ischemia / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D020169:Caspases / Q000378:metabolism; D002465:Cell Movement / Q000235:genetics*; D002470:Cell Survival; D002478:Cells, Cultured; D002544:Cerebral Infarction / Q000473:pathology / Q000517:prevention & control; D018014:Gene Transfer Techniques; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D018696:Neuroprotective Agents; D009569:Nitric Oxide / Q000378:metabolism; D010455:Peptides / Q000235:genetics*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism
D018696:Neuroprotective Agents; D010455:Peptides; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D013481:Superoxides; D053607:Adrenomedullin; D009569:Nitric Oxide; D019255:NADPH Oxidases; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D020169:Caspases