Continuous intravenous infusion of glucose induces endogenous hyperinsulinaemia and lamellar histopathology in Standardbred horses

de Laat, Melody A., Sillence, Martin N., McGowan, Catherine M., & Pollitt, Christopher C. (2012) Continuous intravenous infusion of glucose induces endogenous hyperinsulinaemia and lamellar histopathology in Standardbred horses. The Veterinary Journal, 191(3), pp. 317-322.

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Abstract

Endocrinopathic laminitis is frequently associated with hyperinsulinaemia but the role of glucose in the pathogenesis of the disease has not been fully investigated. This study aimed to determine the endogenous insulin response to a quantity of glucose equivalent to that administered during a laminitis-inducing, euglycaemic, hyperinsulinaemic clamp, over 48. h in insulin-sensitive Standardbred racehorses. In addition, the study investigated whether glucose infusion, in the absence of exogenous insulin administration, would result in the development of clinical and histopathological evidence of laminitis. Glucose (50% dextrose) was infused intravenously at a rate of 0.68 mL/kg/h for 48. h in treated horses (n = 4) and control horses (n = 3) received a balanced electrolyte solution (0.68 mL/kg/h). Lamellar histology was examined at the conclusion of the experiment. Horses in the treatment group were insulin sensitive (M value 0.039 ± 0.0012. mmol/kg/min and M-to-I ratio (100×) 0.014 ± 0.002) as determined by an approximated hyperglycaemic clamp. Treated horses developed glycosuria, hyperglycaemia (10.7 ± 0.78. mmol/L) and hyperinsulinaemia (208 ± 26.1. μIU/mL), whereas control horses did not. None of the horses became lame as a consequence of the experiment but all of the treated horses developed histopathological evidence of laminitis in at least one foot. Combined with earlier studies, the results showed that laminitis may be induced by either insulin alone or a combination of insulin and glucose, but that it is unlikely to be due to a glucose overload mechanism. Based on the histopathological data, the potential threshold for insulin toxicity (i.e. laminitis) in horses may be at or below a serum concentration of ∼200. μIU/mL.

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ID Code: 51407
Item Type: Journal Article
Refereed: Yes
Keywords: Equine, Hyperglycaemia, Insulin, Laminitis
DOI: 10.1016/j.tvjl.2011.07.007
ISSN: 1090-0233
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2011 Elsevier Ltd.
Copyright Statement: This is the author’s version of a work that was accepted for publication in The Veterinary Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in The Veterinary Journal, [VOL 191, ISSUE 3, (2012)] DOI: 10.1016/j.tvjl.2011.07.007
Deposited On: 03 Jul 2012 22:53
Last Modified: 31 Aug 2013 01:08

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