The impact of prolonged hyperinsulinaemia on glucose transport in equine skeletal muscle and digital lamellae

de Laat, Melody, Clement, Chelsie, Sillence, Martin, McGowan, Catherine, Pollitt, Christopher, & Lacombe, Veronique (2015) The impact of prolonged hyperinsulinaemia on glucose transport in equine skeletal muscle and digital lamellae. Equine Veterinary Journal, 47(4), pp. 494-501.

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Abstract

REASONS FOR PERFORMING STUDY

An increased incidence of metabolic disease in horses has led to heightened recognition of the pathological consequences of insulin resistance (IR). Laminitis, failure of the weight-bearing digital lamellae, is an important consequence. Altered trafficking of specialised glucose transporters (GLUTs) responsible for glucose uptake, are central to the dysregulation of glucose metabolism and may play a role in laminitis pathophysiology.

OBJECTIVES

We hypothesised that prolonged hyperinsulinaemia alters the regulation of glucose transport in insulin-sensitive tissue and digital lamellae. Our objectives were to compare the relative protein expression of major GLUT isoforms in striated muscle and digital lamellae in healthy horses and during hyperinsulinaemia.

STUDY DESIGN

Randomised, controlled study.

METHODS

Prolonged hyperinsulinaemia and lamellar damage were induced by a prolonged-euglycaemic hyperinsulinaemic clamp (p-EHC) or a prolonged-glucose infusion (p-GI) and results were compared to electrolyte-treated controls. GLUT protein expression was examined with immunoblotting.

RESULTS

Lamellar tissue contained more GLUT1 protein than skeletal muscle (p = 0.002) and less GLUT4 than the heart (p = 0.037). During marked hyperinsulinaemia and acute laminitis (induced by the p-EHC), GLUT1 protein expression was decreased in skeletal muscle (p = 0.029) but unchanged in the lamellae, while novel GLUTs (8; 12) were increased in the lamellae (p = 0.03), but not skeletal muscle. However, moderate hyperinsulinaemia and subclinical laminitis (induced by the p-GI) did not cause differential GLUT protein expression in the lamellae vs. control horses.

CONCLUSIONS

The results suggest that lamellar tissue functions independently of insulin and that IR may not be an essential component of laminitis aetiology. Marked differences in GLUT expression exist between insulin-sensitive and insulin-independent tissues during metabolic dysfunction in horses. The different expression profiles of novel GLUTs during acute and subclinical laminitis may be important to disease pathophysiology and require further investigation.

Impact and interest:

4 citations in Scopus
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6 citations in Web of Science®

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10 since deposited on 11 Aug 2014
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ID Code: 74915
Item Type: Journal Article
Refereed: Yes
Keywords: horse, GLUT, insulin, insulin resistance, laminitis
DOI: 10.1111/evj.12320
ISSN: 2042-3306
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000)
Australian and New Zealand Standard Research Classification > AGRICULTURAL AND VETERINARY SCIENCES (070000)
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Funding:
  • ANIMAL HEALTH FOUNDA/Unknown
Copyright Owner: Copyright 2014 John Wiley & Sons, Inc
Deposited On: 11 Aug 2014 23:52
Last Modified: 03 Aug 2016 22:07

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