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Abstract

Introduction

Protocol

Representative Results

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Acknowledgements

Materials

References

Medicine

A Model of Chronic Nutrient Infusion in the Rat

Published: August 14th, 2013

DOI:

10.3791/50267

1Montreal Diabetes Research Center, CRCHUM, 2Department of Medicine, University of Montreal

A protocol for chronic infusions of glucose and Intralipid in rats is described. This model can be used to study the impact of nutrient excess on organ function and physiological parameters.

Chronic exposure to excessive levels of nutrients is postulated to affect the function of several organs and tissues and to contribute to the development of the many complications associated with obesity and the metabolic syndrome, including type 2 diabetes. To study the mechanisms by which excessive levels of glucose and fatty acids affect the pancreatic beta-cell and the secretion of insulin, we have established a chronic nutrient infusion model in the rat. The procedure consists of catheterizing the right jugular vein and left carotid artery under general anesthesia; allowing a 7-day recuperation period; connecting the catheters to the pumps using a swivel and counterweight system that enables the animal to move freely in the cage; and infusing glucose and/or Intralipid (a soybean oil emulsion which generates a mixture of approximately 80% unsaturated/20% saturated fatty acids when infused with heparin) for 72 hr. This model offers several advantages, including the possibility to finely modulate the target levels of circulating glucose and fatty acids; the option to co-infuse pharmacological compounds; and the relatively short time frame as opposed to dietary models. It can be used to examine the mechanisms of nutrient-induced dysfunction in a variety of organs and to test the effectiveness of drugs in this context.

Chronically elevated levels of glucose and lipids in the circulation have been proposed to contribute to the pathogenesis of type 2 diabetes by altering the function of several organs implicated in the maintenance of glucose homeostasis including, but not limited to, the pancreatic beta-cell (reviewed in 1). The glucotoxicity hypothesis posits that chronic hyperglycemia aggravates the beta-cell defect which gave rise to hyperglycemia in the first place, thus creating a vicious cycle and contributing to the deterioration of glucose control in type 2 diabetes patients. Likewise, the glucolipotoxicity hypothesis proposes that concomitant elevations of....

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Overview: The procedure consists of catheterizing the right jugular vein and left carotid artery under general anesthesia; allowing a 7-day recuperation period; connecting the catheters to the pumps using a swivel and counterweight system that enables the animal to move freely in the cage; and infusing glucose and/or Intralipid (a soybean oil emulsion which generates a mixture of approximately 80% unsaturated/20% saturated fatty acids when infused with heparin 9) for 72 hr.

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Out of a series of 42 rats which underwent surgery, 5 rats were lost during the post-operative period and 1 rat was lost during the infusion, representing an overall success rate of 86%. The average body weight of the 37 rats that were eventually infused was 608±5 g before surgery and 588±6 g at the initiation of the infusion (mean±SE; n=37; P<0.0001 by paired t-test). The following representative results were obtained in 2 infusion groups: Saline (SAL), and Glucose + Intralipid (GLU+IL). .......

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Although a number of previous studies have employed chronic infusions of glucose (e.g. 10-15) or lipids (e.g. 16,17) in rodents, to our knowledge the combined infusion of both fuels has only been reported in mice 18. The chronic infusion model presented here offers several advantages to study the effects on nutrient excess on a variety of biological functions in rats. First, it does not involve genetically obese rodents, and since common obesity in humans is polyge.......

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This work was supported by the National Institutes of Health (R01DK58096 to Vincent Poitout). Vincent Poitout holds the Canada Research Chair in Diabetes and Pancreatic Beta-cell Function. Bader Zarrouki received post-doctoral fellowships from Merck and Eli Lilly. Ghislaine Fontés was supported by a post-doctoral fellowship from the Canadian Diabetes Association.

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Name Company Catalog Number Comments
Name of Reagent/Material Company Catalog Number Comments
Saline 0.9% BD JB1324
Dextrose 70% McKesson
Intralipid 20% Fresenius Kabi JB6023
Metricide (Glutaraldehyde 2.6%) Metrex 11-1401
Heparin Sodium 10,000 USP u/ml PPC
Carprofen Metacam
Glycopyrrolate Sandoz
Isoflurane Abbott
Chlohexidine 2%
Alcohol 70%
Iodine
PE-50 BD 427411
CO-EX T22 Instech Solomon BCOEX-T22
Connector 22G Instech Solomon SC22/15
Swivel 22G Instech Solomon 375/22PS
Y-Connector 22G Instech Solomon
Counterbalance and arm Instech Solomon CM375BP
23 G blunted needles Instech Solomon LS23
23 G canulation pins Instech Solomon SP23/12
Tethers (12 inch) Lomir RT12D
Infusion jackets Lomir RJ01, RJ02, RJ03, RJ04
(SM-XL)
Tether attachment piece Lomir RS T1
60 ml syringe BD 309653
1 ml syringe BD 309602

  1. Poitout, V., Robertson, R. P. Glucolipotoxicity: fuel excess and beta-cell dysfunction. Endocr. Rev. 29, 351-366 (2008).
  2. Poitout, V., et al. Glucolipotoxicity of the pancreatic beta cell. Biochim. Biophys. Acta. 1801, 289-298 (2010).
  3. Unger, R. H. Minireview: weapons of lean body mass destruction: the role of ectopic lipids in the metabolic syndrome. Endocrinology. 144, 5159-5165 (2003).
  4. Harmon, J. S., Gleason, C. E., Tanaka, Y., Poitout, V., Robertson, R. P. Antecedent hyperglycemia, not hyperlipidemia, is associated with increased islet triacylglycerol content and decreased insulin gene mRNA level in Zucker diabetic fatty rats. Diabetes. 50, 2481-2486 (2001).
  5. Bachar, E., Ariav, Y., Cerasi, E., Kaiser, N., Leibowitz, G. Neuronal nitric oxide synthase protects the pancreatic beta cell from glucolipotoxicity-induced endoplasmic reticulum stress and apoptosis. Diabetologia. 53, 2177-2187 (2010).
  6. Peyot, M. L., et al. Beta-cell failure in diet-induced obese mice stratified according to body weight gain: secretory dysfunction and altered islet lipid metabolism without steatosis or reduced beta-cell mass. Diabetes. 59, 2178-2187 (2010).
  7. Hagman, D. K., et al. Cyclical and alternating infusions of glucose and intralipid in rats inhibit insulin gene expression and Pdx-1 binding in islets. Diabetes. 57, 424-431 (2008).
  8. Fontes, G., et al. Glucolipotoxicity age-dependently impairs beta cell function in rats despite a marked increase in beta cell mass. Diabetologia. 53, 2369-2379 (2010).
  9. Stein, D. T., et al. Essentiality of circulating fatty acids for glucose-stimulated insulin secretion in the fasted rat. J. Clin. Invest. 97, 2728-2735 (1996).
  10. Leahy, J. L., Cooper, H. E., Weir, G. C. Impaired insulin secretion associated with near normoglycemia. Study in normal rats with 96-h in vivo glucose infusions. Diabetes. 36, 459-464 (1987).
  11. Hager, S. R., Jochen, A. L., Kalkhoff, R. K. Insulin resistance in normal rats infused with glucose for 72 h. The American Journal of Physiology. 260, 353-362 (1991).
  12. Laybutt, D. R., Chisholm, D. J., Kraegen, E. W. Specific adaptations in muscle and adipose tissue in response to chronic systemic glucose oversupply in rats. The American Journal of Physiology. 273, E1-E9 (1997).
  13. Jonas, J. C., et al. High glucose stimulates early response gene c-Myc expression in rat pancreatic beta cells. The Journal of Biological Chemistry. 276, 35375-35381 (2001).
  14. Tang, C., et al. Glucose-induced beta cell dysfunction in vivo in rats: link between oxidative stress and endoplasmic reticulum stress. Diabetologia. 55, 1366-1379 (2012).
  15. Alonso, L. C., et al. Glucose infusion in mice: a new model to induce beta-cell replication. Diabetes. 56, 1792-1801 (2007).
  16. Magnan, C., Gilbert, M., Kahn, B. B. Chronic free fatty acid infusion in rats results in insulin resistance but no alteration in insulin-responsive glucose transporter levels in skeletal muscle. Lipids. 31, 1141-1149 (1996).
  17. Goh, T. T., et al. Lipid-induced beta-cell dysfunction in vivo in models of progressive beta-cell failure. Am. J. Physiol. Endocrinol. Metab. 292, 549-560 (2007).
  18. Pascoe, J., et al. Free fatty acids block glucose-induced beta-cell proliferation in mice by inducing cell cycle inhibitors p16 and p18. Diabetes. 61, 632-641 (2012).
  19. Bell, C. G., Walley, A. J., Froguel, P. The genetics of human obesity. Nature Reviews. Genetics. 6, 221-234 (2005).
  20. Fontes, G., Hagman, D. K., Latour, M. G., Semache, M., Poitout, V. Lack of preservation of insulin gene expression by a glucagon-like peptide 1 agonist or a dipeptidyl peptidase 4 inhibitor in an in vivo model of glucolipotoxicity. Diabetes Res. Clin. Pract. 87, 322-328 (2010).
  21. Crawford, P. A., Schaffer, J. E. Metabolic stress in the myocardium: Adaptations of gene expression. Journal of Molecular and Cellular Cardiology. , (2012).
  22. Kewalramani, G., Bilan, P. J., Klip, A. Muscle insulin resistance: assault by lipids, cytokines and local macrophages. Curr. Opin. Clin. Nutr. Metab Care. 13, 382-390 (2010).
  23. Cusi, K. Role of obesity and lipotoxicity in the development of nonalcoholic steatohepatitis: pathophysiology and clinical implications. Gastroenterology. 142, 711-725 (2012).

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