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American journal of physiology. Endocrinology and metabolism2015; 310(1); E61-E72; doi: 10.1152/ajpendo.00362.2015

Equine hyperinsulinemia: investigation of the enteroinsular axis during insulin dysregulation.

Abstract: Compared with some other species, insulin dysregulation in equids is poorly understood. However, hyperinsulinemia causes laminitis, a significant and often lethal disease affecting the pedal bone/hoof wall attachment site. Until recently, hyperinsulinemia has been considered a counterregulatory response to insulin resistance (IR), but there is growing evidence to support a gastrointestinal etiology. Incretin hormones released from the proximal intestine, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide, augment insulin secretion in several species but require investigation in horses. This study investigated peripheral and gut-derived factors impacting insulin secretion by comparing the response to intravenous (iv) and oral d-glucose. Oral and iv tests were performed in 22 ponies previously shown to be insulin dysregulated, of which only 15 were classified as IR (iv test). In a more detailed study, nine different ponies received four treatments: d-glucose orally, d-glucose iv, oats, and commercial grain mix. Insulin, glucose, and incretin concentrations were measured before and after each treatment. All nine ponies showed similar iv responses, but five were markedly hyperresponsive to oral d-glucose and four were not. Insulin responsiveness to oral d-glucose was strongly associated with blood glucose concentrations and oral glucose bioavailability, presumably driven by glucose absorption/distribution, as there was no difference in glucose clearance rates. Insulin was also positively associated with the active amide of GLP-1 following d-glucose and grain. This study has confirmed a functional enteroinsular axis in ponies that likely contributes to insulin dysregulation that may predispose them to laminitis. Moreover, iv tests for IR are not reliable predictors of the oral response to dietary nonstructural carbohydrate.
Copyright © 2016 the American Physiological Society.
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Publication Date: 2015-11-03 PubMed ID: 26530154DOI: 10.1152/ajpendo.00362.2015Google 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.

The research article studies insulin imbalance in horses, particularly linking digestive system hormone activity to insulin issues and resultant health problems like laminitis. The article suggests that methods for testing insulin resistance in horses require reevaluation considering the observable association between gut-derived factors and insulin regulation.

Insulin Dysregulation in Equines

  • The research mainly focuses on understanding the causes and mechanics of hyperinsulinemia in horses (equids). Hyperinsulinemia, a condition where horses have abnormally high levels of insulin in their blood, can lead to laminitis – a painful and potentially fatal condition affecting horse feet.
  • Previously, hyperinsulinemia in horses was thought to be a response to insulin resistance, but this study presents evidence that significant contributing factors may originate from the gastrointestinal system.
  • Incretin hormones like glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide, which come from the early sections of the intestine, are known to boost insulin secretion in various species. The effect of these hormones on insulin secretion in horses is examined in this study.

Research Methodology and Findings

  • The research involved tests on 22 ponies, previously identified as having insulin dysregulation. Of these, 15 were classified as insulin resistant. The ponies were subjected to two tests, one involving intravenous delivery of glucose and the other oral intake.
  • A more detailed study on nine different ponies compared the insulin, glucose, and incretin levels subsequent to four different treatments: oral d-glucose, intravenous d-glucose, oats, and commercial grain mix.
  • The findings showed important variations in the ponies’ insulin responses between the oral and intravenous glucose administration test. Five of the nine ponies exhibited significant hyperresponsiveness to orally administered d-glucose, while four did not.
  • The insulin response to oral d-glucose was seen as strongly related to blood glucose concentrations and oral glucose bioavailability. Factors like glucose absorption and distribution seem to influence this as glucose clearance rates showed no difference.
  • The active variant of GLP-1 was seen as positively associated with insulin following d-glucose and grain treatment, indicating its role in insulin regulation.

Conclusion and Implication

  • The research concludes that there is a functional ‘enteroinsular axis’ in ponies, suggesting that the digestive system and insulin regulation are closely linked, and contributing to insulin dysregulation that may make them prone to laminitis.
  • One of the significant observations from the research is the unreliability of intravenous tests for predicting the oral response to dietary carbohydrates in the body. This implication calls for a review and possible revision of methods for diagnosing insulin resistance in horses.

Cite This Article

APA
de Laat MA, McGree JM, Sillence MN. (2015). Equine hyperinsulinemia: investigation of the enteroinsular axis during insulin dysregulation. Am J Physiol Endocrinol Metab, 310(1), E61-E72. https://doi.org/10.1152/ajpendo.00362.2015

Publication

American journal of physiology. Endocrinology and metabolism
ISSN: 1522-1555
NlmUniqueID: 100901226
Country: United States
Language: English
Volume: 310
Issue: 1
Pages: E61-E72

Researcher Affiliations

de Laat, M A
  • Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia melody.delaat@qut.edu.au.
McGree, J M
  • Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia.
Sillence, M N
  • Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland, Australia.

MeSH Terms

  • Animal Feed
  • Animals
  • Diet
  • Dietary Carbohydrates / pharmacology
  • Enteroendocrine Cells / metabolism
  • Gastrointestinal Tract / drug effects
  • Gastrointestinal Tract / metabolism
  • Glucose Tolerance Test / methods
  • Glucose Tolerance Test / veterinary
  • Horse Diseases / metabolism
  • Horses / metabolism
  • Hyperinsulinism / metabolism
  • Hyperinsulinism / veterinary
  • Incretins / metabolism
  • Insulin / metabolism
  • Insulin Resistance

Citations

This article has been cited 49 times.
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