title: Metformin stimulates ischemia-induced revascularization through an eNOS dependent pathway in the ischemic hindlimb mice model.
abstract: OBJECTIVE
  As first-line treatment for type 2 diabetes, metformin has gained a strong position. In addition, type 2 diabetics benefit from the fact that metformin is associated with a reduction in cardiovascular events. Nevertheless, there is a dearth of information concerning the functional role of metformin in regulating angiogenesis. Our present study explores whether metformin is involved in the modulation of the revascularization processes in vivo by employing a hindlimb mice model of ischemia-induced angiogenesis.
  
  
  METHODS
  For comparative purposes, randomly selected wild-type (WT) mice or endothelial nitric oxide synthase (eNOS) deficient mice were assigned to one of two groups. One group was orally administered a daily dose of metformin through a gastric tube whereas the other group served as a control with no metformin administered. Both groups were subjected to unilateral hindlimb ischemia. Laser Doppler analysis coupled with capillary density staining with CD31was the method employed to determine revascularization. Adenosine monophosphate-activated protein kinase (AMPK) and eNOS phosphorylation levels were assessed using Western blot analysis.
  
  
  RESULTS
  Subsequent to hindlimb ischemic surgery, in comparison to the nontreated mice, metformin-treated WT mice showed accelerated limb perfusion, which was substantiated by laser Doppler blood-flow measurements and the presence of increased capillary density in the ischemic adductor muscle. Treatment with metformin significantly enhanced the increase in AMPK and eNOS phosphorylation levels of muscle tissues in WT mice induced by ischemia. In eNOS- deficient knockout mice, there was a significant increase in ischemic tissue AMPK phosphorylation induced by metformin; however, blood flow recovery in ischemic limb after surgery was unaffected.
  
  
  CONCLUSIONS
  Metformin promoted revascularization in the presence of tissue ischemia through an AMPK/eNOS-related mechanism. Our study indicates that, in addition to its glucose-lowering effect, metformin fosters improved revascularization, which is responsible for its positive effect on patients with critical limb ischemia.
authors.affiliation: Department of Vascular Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Shibata
authors.affiliation: Department of Molecular Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ouchi
authors.affiliation: Department of Vascular Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sugimoto
authors.affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Murohara
authors.affiliation: Department of Vascular Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address: komori@med.nagoya-u.ac.jp.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Komori
mesh_terms: D000263:Adenylate Kinase / Q000378:metabolism; D043925:Angiogenesis Inducing Agents / Q000494:pharmacology*; D000818:Animals; D001783:Blood Flow Velocity; D002196:Capillaries / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D004789:Enzyme Activation; D006614:Hindlimb; D007511:Ischemia / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects* / Q000201:enzymology; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D020127:Recovery of Function; D012039:Regional Blood Flow; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D043925:Angiogenesis Inducing Agents; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D008687:Metformin; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D000263:Adenylate Kinase