title: Effect of limb demand ischemia on autophagy and morphology in mice.
abstract: BACKGROUND
  Obesity is a major risk factor for diabetes and peripheral arterial disease, which frequently leads to lower limb demand ischemia. Skeletal muscle autophagy and mitochondrial biogenesis are important processes for proper oxidative capacity and energy metabolism, which are compromised in diabetes. This study compares autophagy, mitochondrial biogenesis, energy metabolism, and morphology in the hind limbs of obese diabetic mice subjected to demand or sedentary ischemia.
  
  
  METHODS
  Unilateral hind limb demand ischemia was created in a group of diet-induced obese mice after femoral artery ligation and 4 wk of daily exercise. A parallel group of mice underwent femoral artery ligation but remained sedentary for 4 wk. Hind limb muscles were analyzed for markers of autophagy, mitochondrial biogenesis, adenosine triphosphate, and muscle tissue morphology.
  
  
  RESULTS
  At the end of the 4-wk exercise period, demand ischemia increased the autophagy mediator Beclin-1, but it did not alter the autophagy indicator, LC3B-II/I ratio, or markers of mitochondrial biogenesis, optic atrophy/dynamin-related protein. In contrast, exercise significantly increased the level of mitochondrial protein-succinate dehydrogenase subunit-A and reduced adipocyte accumulation and the percentage of centrally nucleated myofibers in the demand ischemia limb. In addition, demand ischemia resulted in decreased uncoupling protein-3 levels without altering muscle adenosine triphosphate or pS473-Akt levels.
  
  
  CONCLUSIONS
  Limb demand ischemia markedly decreased adipocyte accumulation and enhanced muscle regeneration in obese mice, but it did not appear to enhance autophagy, mitochondrial biogenesis, energy metabolism, or insulin sensitivity. Future studies aimed at evaluating novel therapies that enhance autophagy and mitochondrial biogenesis in diabetes with peripheral arterial disease are warranted.
authors.affiliation: Division of Vascular and Endovascular Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. Electronic address: halbadawi@mgh.harvard.edu.
authors.forename: Hassan
authors.initials: H
authors.lastname: Albadawi
authors.affiliation: Division of Vascular and Interventional Radiology, Department of Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Rahmi
authors.initials: R
authors.lastname: Oklu
authors.affiliation: Division of Vascular and Endovascular Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: John D
authors.initials: JD
authors.lastname: Milner
authors.affiliation: Division of Vascular and Endovascular Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Thuy P
authors.initials: TP
authors.lastname: Uong
authors.affiliation: Division of Vascular and Endovascular Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Hyung-Jin
authors.initials: HJ
authors.lastname: Yoo
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: William G
authors.initials: WG
authors.lastname: Austen
authors.affiliation: Division of Vascular and Endovascular Surgery, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Watkins
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017667:Adipocytes / Q000473:pathology; D000818:Animals; D001343:Autophagy; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D007333:Insulin Resistance; D007473:Ion Channels / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D035002:Lower Extremity / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008810:Mice, Inbred C57BL; D008931:Mitochondria, Muscle / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009765:Obesity / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D010805:Physical Conditioning, Animal; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012038:Regeneration; D000071247:Uncoupling Protein 3
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3; D000255:Adenosine Triphosphate; D051057:Proto-Oncogene Proteins c-akt
keywords: Autophagy; Diet-induced obesity; Limb demand ischemia; Mitochondrial biogenesis; Muscle regeneration; Peripheral arterial disease; Type-2 diabetes