title: Effect of dietary nonstructural carbohydrate content on activation of 5'-adenosine monophosphate-activated protein kinase in liver, skeletal muscle, and digital laminae of lean and obese ponies.
abstract: BACKGROUND
  In EMS-associated laminitis, laminar failure may occur in response to energy failure related to insulin resistance (IR) or to the effect of hyperinsulinemia on laminar tissue. 5'-Adenosine-monophosphate-activated protein kinase (AMPK) is a marker of tissue energy deprivation, which may occur in IR.
  
  
  OBJECTIVE
  To characterize tissue AMPK regulation in ponies subjected to a dietary carbohydrate (CHO) challenge.
  
  
  METHODS
  Twenty-two mixed-breed ponies.
  
  
  METHODS
  Immunohistochemistry and immunoblotting for total AMPK and phospho(P)-AMPK and RT-qPCR for AMPK-responsive genes were performed on laminar, liver, and skeletal muscle samples collected after a 7-day feeding protocol in which ponies stratified on body condition score (BCS; obese or lean) were fed either a low-CHO diet (ESC + starch, approximately 7% DM; n = 5 obese, 5 lean) or a high-CHO diet (ESC + starch, approximately 42% DM; n = 6 obese, 6 lean).
  
  
  RESULTS
  5'-Adenosine-monophosphate-activated protein kinase was immunolocalized to laminar keratinocytes, dermal constituents, and hepatocytes. A high-CHO diet resulted in significantly decreased laminar [P-AMPK] in lean ponies (P = .03), but no changes in skeletal muscle (lean, P = .33; obese, P = .43) or liver (lean, P = .84; obese, P = .13) [P-AMPK]. An inverse correlation existed between [blood glucose] and laminar [P-AMPK] in obese ponies on a high-CHO diet.
  
  
  CONCLUSIONS
  Laminar tissue exhibited a normal response to a high-CHO diet (decreased [P-AMPK]), whereas this response was not observed in liver and skeletal muscle in both lean (skeletal muscle, P = .33; liver, P = .84) and obese (skeletal muscle, P = .43; liver, P = .13) ponies.
authors.affiliation: The Ohio State University College of Veterinary Medicine, Columbus, OH.
authors.forename: T A
authors.initials: TA
authors.lastname: Burns
authors.forename: M R
authors.initials: MR
authors.lastname: Watts
authors.forename: P S
authors.initials: PS
authors.lastname: Weber
authors.forename: L J
authors.initials: LJ
authors.lastname: McCutcheon
authors.forename: R J
authors.initials: RJ
authors.lastname: Geor
authors.forename: J K
authors.initials: JK
authors.lastname: Belknap
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D015153:Blotting, Western / Q000662:veterinary; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006724:Hoof and Claw / Q000187:drug effects / Q000201:enzymology*; D006734:Horse Diseases / Q000201:enzymology* / Q000378:metabolism; D006736:Horses; D007328:Insulin / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology*; D009765:Obesity / Q000201:enzymology / Q000378:metabolism / Q000662:veterinary*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013851:Thinness / Q000201:enzymology / Q000378:metabolism / Q000662:veterinary*
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D055372:AMP-Activated Protein Kinases
keywords: Energy regulation; Equine metabolic syndrome; Insulin resistance; Laminitis
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