Neuroprotective effects of adenosine monophosphate - Activated protein kinase inhibition and gene deletion in stroke

Background and Purpose - 5' adenosine monophosphate-dependent protein kinase ( AMPK) acts as a metabolic sensor. AMPK is elevated under ischemic conditions, but the role of AMPK in ischemic brain remains controversial. In this study, we examined the effects of AMPK inhibition using both pharmacological and genetic approaches in an in vivo stroke model. Methods - Focal stroke was induced by reversible middle cerebral artery occlusion in male wild-type mice as well as mice deficient in one of the isoforms of the catalytic subunit of AMPK, AMPK alpha-1 or alpha-2. Results - AMPK inhibition was neuroprotective after focal stroke. Mice deficient in AMPK alpha-2 demonstrated significantly smaller infarct volumes compared with wild-type littermates, whereas deletion of AMPK alpha-1 had no effect. Phosphorylation of a major upstream regulator of AMPK, LKB1, was also induced in stroke brain. Conclusions - AMPK activation is detrimental in a model of focal stroke. The AMPK catalytic isoform alpha-2 contributes to the deleterious effects of AMPK activation. AMPK inhibition leads to neuroprotection even when these agents are administered poststroke.