title: Chronic metformin treatment improves post-stroke angiogenesis and recovery after experimental stroke.
abstract: Metformin is currently the first-line treatment drug for type 2 diabetes. Metformin is a well-known activator of AMP-activated protein kinase (AMPK). In experimental studies, metformin has been shown to exert direct vascular effects by increasing vascular endothelial growth factor expression and improving microvascular density. As stroke is the leading cause of long-term disability and angiogenesis is implicated as an important mechanism in functional recovery, we hypothesized that chronic metformin treatment would improve post-stroke functional recovery by enhancing functional microvascular density. For this study, C57BL/6N male mice were subjected to a 60-min middle cerebral artery occlusion, and were given 50 mg/kg/day metformin beginning 24 h post-stroke for 3 weeks. Behavioral recovery was assessed using adhesive-tape removal and the apomorphine-induced turning test. The role of angiogenesis was assessed by counting vessel branch points from fluorescein-conjugated lectin-perfused brain sections. Importantly even if metformin treatment was initiated 24 h after injury it enhanced recovery and significantly improved stroke-induced behavioral deficits. This recovery occurred in parallel with enhanced angiogenesis and with restoration of endogenous cerebral dopaminergic tone and revascularization of ischemic tissue. We assessed if the effects on recovery and angiogenesis were mediated by AMPK. When tested in AMPK α-2 knockout mice, we found that metformin treatment did not have the same beneficial effects on recovery and angiogenesis, suggesting that metformin-induced angiogenic effects are mediated by AMPK. The results from this study suggest that metformin mediates post-stroke recovery by enhancing angiogenesis, and these effects are mediated by AMPK signaling.
authors.affiliation: Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA.
authors.forename: Venugopal R
authors.initials: VR
authors.lastname: Venna
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Hammond
authors.forename: Nickolas S
authors.initials: NS
authors.lastname: Mancini
authors.forename: Louise D
authors.initials: LD
authors.lastname: McCullough
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D018491:Dopamine Agonists / Q000494:pharmacology; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010812:Physical Stimulation; D011897:Random Allocation; D020127:Recovery of Function / Q000187:drug effects* / Q000502:physiology; D020521:Stroke; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D018491:Dopamine Agonists; D018696:Neuroprotective Agents; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D008687:Metformin; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases; D001058:Apomorphine
keywords: AMPK; apomorphine; cerebral ischemia; metformin