Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; The Netherlands Consortium for Systems Biology, Den Haag, The Netherlands;
Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;
Am J Physiol Endocrinol Metab. 2015 Nov 15;309(10):E874-83. doi: 10.1152/ajpendo.00292.2015. Epub 2015 Sep 29.
Insulin resistance is associated with ectopic lipid accumulation. Physical activity improves insulin sensitivity, but the impact of exercise on lipid handling in insulin-resistant tissues remains to be elucidated. The present study characterizes the effects of acute exercise on lipid content and dietary lipid partitioning in liver and skeletal muscle of lean and diabetic rats by use of magnetic resonance spectroscopy (MRS). After baseline measurements, rats were randomized to exercise or no-exercise groups. A subset of animals was subjected to MRS directly after 1 h of treadmill running for measurement of total intrahepatocellular lipid (IHCL) and intramyocellular lipid (IMCL) content (n=7 lean and diabetic rats). The other animals were administered 13C-labeled lipids orally after treadmill visit (with or without exercise) followed by MRS measurements after 4 and 24 h to determine the 13C enrichment of IHCL and IMCL (n=8 per group). Total IHCL and IMCL content were fivefold higher in diabetic vs. lean rats (P<0.001). Exercise did not significantly affect IHCL content but reduced IMCL by 25±7 and 33±4% in lean and diabetic rats (P<0.05), respectively. Uptake of dietary lipids in liver and muscle was 2.3-fold greater in diabetic vs. lean rats (P<0.05). Prior exercise did not significantly modulate dietary lipid uptake into muscle, but in liver of both lean and diabetic rats, lipid uptake was 44% reduced after acute exercise (P<0.05). In conclusion, IMCL but not IHCL represents a viable substrate source during exercise in both lean and diabetic rats, and exercise differentially affects dietary lipid uptake in muscle and liver.
胰岛素抵抗与异位脂质积累有关。身体活动可以提高胰岛素敏感性，但运动对胰岛素抵抗组织中脂质处理的影响仍有待阐明。本研究通过磁共振波谱（MRS）来描述急性运动对瘦型和糖尿病大鼠肝脏和骨骼肌中脂质含量和饮食脂质分配的影响。在基线测量后，大鼠被随机分为运动或不运动组。一部分动物在跑步机跑步 1 小时后直接进行 MRS，以测量肝细胞内总脂质（IHCL）和肌内脂质（IMCL）含量（n=7 只瘦型和糖尿病大鼠）。另一部分动物在跑步机访问后口服 13C 标记的脂质（有或没有运动），然后在 4 小时和 24 小时后进行 MRS 测量，以确定 IHCL 和 IMCL 的 13C 丰度（每组 n=8）。与瘦型大鼠相比，糖尿病大鼠的总 IHCL 和 IMCL 含量高五倍（P<0.001）。运动对 IHCL 含量没有显著影响，但使瘦型和糖尿病大鼠的 IMCL 分别减少了 25±7%和 33±4%（P<0.05）。与瘦型大鼠相比，糖尿病大鼠肝脏和肌肉对饮食脂质的摄取增加了两倍（P<0.05）。运动前运动并没有显著调节肌肉对饮食脂质的摄取，但在瘦型和糖尿病大鼠的肝脏中，急性运动后脂质摄取减少了 44%（P<0.05）。综上所述，在瘦型和糖尿病大鼠中，IMCL 而不是 IHCL 是运动时的一种可行的底物来源，运动对肌肉和肝脏中饮食脂质的摄取有不同的影响。
