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Journal of veterinary internal medicine2014; 28(4); 1280-1288; doi: 10.1111/jvim.12356

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: 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.
Copyright © 2014 by the American College of Veterinary Internal Medicine.
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Publication Date: 2014-04-20 PubMed ID: 24750267PubMed Central: PMC4857936DOI: 10.1111/jvim.12356Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates how a carbohydrate-rich diet affects the activation of a protein known as AMPK in various tissues of both lean and obese ponies. The research was driven by the desire to better understand the metabolic disorder, equine metabolic syndrome (EMS)-associated laminitis.

Objectives and Methodology

  • The objective of this study was to evaluate the effect of a high-carbohydrate diet on the regulation of 5′-Adenosine-monophosphate-activated protein kinase (AMPK) – a protein involved in cellular energy balance – in the tissues of lean and obese ponies.
  • The research involved twenty-two mixed-breed ponies that were categorised based on their body condition score (BCS) into either obese or lean.
  • These ponies underwent a dietary challenge where they were fed a diet either low in nonstructural carbohydrates (cholestrol) (approximately 7% Dry Matter) or high in nonstructural carbohydrates (approximately 42% Dry Matter) for a period of seven days.
  • Different tissues – laminar tissue, liver, and skeletal muscle – were collected from the ponies after the feeding protocol.
  • Tests, including immunohistochemistry and immunoblotting for total AMPK and phospho(P)-AMPK as well as RT-qPCR for AMPK-responsive genes, were conducted on these samples.

Key Findings

  • AMPK was identified in laminar keratinocytes, dermal constituents, and hepatocytes.
  • Feeding the ponies a high-CHO diet led to a significant decrease in the presence of AMPK in the laminar tissue of lean ponies. However, the high-carbohydrate diet did not result in any changes in the presence of AMPK in the skeletal muscle and liver tissues of both lean and obese ponies.
  • Researchers found a negative correlation between blood glucose and the presence of AMPK in the laminar tissue of obese ponies on a high-CHO diet.

Conclusions

  • The research concluded that laminar tissue exhibited a standard response to a high-carbohydrate diet by showing decreased levels of AMPK. This response, however, was not seen in liver and skeletal muscle tissues in both lean and obese ponies.
  • This differential response could provide insights into the metabolic disorder equine metabolic syndrome (EMS)-associated laminitis.

Cite This Article

APA
Burns TA, Watts MR, Weber PS, McCutcheon LJ, Geor RJ, Belknap JK. (2014). 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. J Vet Intern Med, 28(4), 1280-1288. https://doi.org/10.1111/jvim.12356

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 28
Issue: 4
Pages: 1280-1288

Researcher Affiliations

Burns, T A
  • The Ohio State University College of Veterinary Medicine, Columbus, OH.
Watts, M R
    Weber, P S
      McCutcheon, L J
        Geor, R J
          Belknap, J K

            MeSH Terms

            • AMP-Activated Protein Kinases / metabolism
            • Animals
            • Blood Glucose / analysis
            • Blotting, Western / veterinary
            • Dietary Carbohydrates / pharmacology
            • Enzyme Activation / drug effects
            • Hoof and Claw / drug effects
            • Hoof and Claw / enzymology
            • Horse Diseases / enzymology
            • Horse Diseases / metabolism
            • Horses
            • Insulin / blood
            • Liver / drug effects
            • Liver / enzymology
            • Muscle, Skeletal / drug effects
            • Muscle, Skeletal / enzymology
            • Obesity / enzymology
            • Obesity / metabolism
            • Obesity / veterinary
            • Real-Time Polymerase Chain Reaction / veterinary
            • Thinness / enzymology
            • Thinness / metabolism
            • Thinness / veterinary

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