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Horm Metab Res 2009; 41(4): 287-293
DOI: 10.1055/s-0028-1102937
Original Basic

© Georg Thieme Verlag KG Stuttgart · New York

Effects of Exercise Training on Hepatic Microsomal Triglyceride Transfer Protein Content in Rats

N. A. Chapados 1 , M. Seelaender 2 , E. Levy 3 , J-M. Lavoie 1
  • 1Department of Kinesiology, University of Montreal, Montreal, Canada
  • 2Molecular Biology of the Cell Group, Institute of Biomedical Sciences, University of São Paulo, Brazil
  • 3Research Center, Sainte-Justine Hospital and Department of Nutrition, University of Montreal, Montreal, Canada
Further Information

Publication History

received 05.08.2008

accepted 15.10.2008

Publication Date:
20 November 2008 (online)

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Abstract

Microsomal triglyceride transfer protein (MTP) is a protein that exerts a central regulatory role in very-low-density lipoprotein (VLDL) assembly and secretion. The purpose of the study was to investigate the effects of an exercise-training program on hepatic content of MTP and its relation to hepatic VLDL-triglyceride (VLDL-TG) production in response to lipid infusion. Female rats either fed a standard (SD) or an obesity-induced high-fat (HF; 43% as energy) diet for 8 weeks were subdivided into sedentary (Sed) and trained (Tr) groups. Exercise training consisted of continuous running on a motor-driven rodent treadmill 5 times/week for 8 weeks. At the end of this period, all rats in the fasted state were intravenously infused with a 20% solution of Intralipid for 3 h followed by an injection of Triton WR1339 to block lipoprotein lipase. An additional control group consisting of Sed rats fed the SD diet was infused with saline (0.9% NaCl). Plasma TG accumulation was thereafter measured during 90 min to estimate VLDL-TG production. Under HF diet, hepatic MTP content and plasma TG accumulation after Triton blockade (thus reflecting VLDL-TG synthesis and secretion) were not changed in Sed rats, whereas liver TG content was highly increased (∼90%; p<0.01). On the other hand, training reduced liver MTP protein content in both SD (−18%) and HF (–23%) fed rats (p<0.05). Plasma VLDL-TG accumulation was also lower (p<0.05) in Tr than in Sed rats fed the HF diet. This effect was not observed in SD fed rats. Furthermore, the exercise training-induced decrease in VLDL-TG production in HF rats was associated with a decrease in liver TG levels. It is concluded that in addition to a reduction in liver TG content, exercise training reduces VLDL synthesis and/or secretion in HF fed rats probably via MTP regulation.

Key words

hepatic steatosis - high-fat diet - VLDL-TG production - lipid infusion

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Correspondence

N. A. Chapados

Department of Kinesiology

University of Montreal

C.P. 6128, Succ. Centre-ville

Montréal (Québec)

Canada H3C 3J7

Phone: +1/514/343 61 11 (4867)

Fax: +1/514/343 21 81

Email: natalie.chapados@umontreal.ca

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