Dietary mannoheptulose has differential effects on fasting and post-prandial glucose oxidation in Labrador Retrievers

Abstract

This study aimed to determine the effects of dietary mannoheptulose (MH; 2 mg kg⁻¹), a glycolytic inhibitor, on glucose oxidation and biomarkers of energy metabolism in neutered, adult, male Labrador Retriever dogs (N = 6). Fasting and post-prandial respiratory quotient (RQ) and energy expenditure (EE) were determined by indirect calorimetry (d 16). Glucose turnover and oxidation were assessed during fasting and repeated meal feeding using indirect calorimetry and a constant intravenous infusion of U-¹³C-glucose (d 18). A sample from the biceps femoris was obtained to determine the muscle protein content of adenosine monophosphate-activated protein kinase (AMPK) and acetyl CoA carboxylase (ACC; total and phosphorylated forms; d 21). MH did not affect EE, serum glucose, insulin or free fatty acids or ACC protein content. In fasting, MH significantly increased the fasting RQ (p = 0.01) and glucose oxidation (p = 0.01) and tended to decrease the ratio of phosphorylated to total AMPK protein content (p = 0.16). In contrast, post-prandial glucose oxidation tended to be lower (p = 0.14) in dogs fed MH. These results suggest that MH has differential effects on fasting and post-prandial whole body glucose and fat oxidation. However, further research that uses a greater number of animals and/or higher dose of MH is required.

Keywords:

• energy expenditure
• glucose oxidation
• Labrador Retriever
• mannoheptulose
• respiratory quotient

Acknowledgements

The authors would like to thank the staff at the P&G Pet Health and Nutrition Centre (Lewisburg OH), especially Lisa Fortener and Liz Fuess for their technical assistance. In addition, the authors would like to thank Laelie Snook, Department of Human Health and Nutritional Sciences, University of Guelph, for her technical assistance and Dr David Wright, Department of Human Health and Nutritional Sciences, University of Guelph, for providing laboratory space and contributing to the interpretation of the immunoblot results.

Funding

This work was supported by P& G Pet Care.

Notes on contributors

E.A.F, G.M.D and A.K.S. are employees of P&G Pet Care.

Additional information

Funding

Funding: This work was supported by P& G Pet Care.