Lau R, Blinn W D, Bonen A, Dyck D J
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, Canada N2L 3G1.
Am J Physiol Endocrinol Metab. 2001 Jul;281(1):E122-9. doi: 10.1152/ajpendo.2001.281.1.E122.
Leptin has been shown to acutely stimulate fatty acid oxidation and triacylglycerol hydrolysis in skeletal muscle. These effects are similar to those induced by muscle contraction alone. Several studies have demonstrated that, during aerobic exercise, plasma leptin concentrations are well maintained; however, none has examined whether the stimulatory effects of leptin and contraction on muscle lipid metabolism are additive. This is the first study to examine the direct effect of leptin on lipid and carbohydrate (CHO) metabolism in isolated oxidative muscle over a range of contraction intensities. We examined the effect of leptin (10 microg/ml) on the synthesis and degradation of muscle lipid pools [phospholipid (PL), diacylglycerol (DG), triacylglycerol (TG)] and palmitate oxidation in isolated resting and contracting (2, 8, and 20 tetani/min) soleus muscles. At rest, leptin increased fatty acid oxidation (+ 40%, P < 0.05) and TG hydrolysis (+ 47%, P < 0.05), while blunting TG esterification (-20%, P < 0.05). Glucose oxidation was unaffected at rest in the presence of leptin. During tetanic contraction, fatty acid oxidation (+20-114%, P < 0.05) and TG esterification (+ 19-33%, P < 0.05) as well as net TG utilization (+ 23%, P < 0.05) were all significantly increased. However, leptin was without further effect on any of these parameters during contraction. Net utilization of intramuscular glycogen, as well as glucose oxidation, was unaffected during contraction by leptin. The findings of the present study indicate that leptin has an important influence on lipid metabolism in resting muscle, but not during contraction.
已证实，瘦素可急性刺激骨骼肌中的脂肪酸氧化和三酰甘油水解。这些作用类似于仅由肌肉收缩所诱导的作用。多项研究表明，在有氧运动期间，血浆瘦素浓度能得到良好维持；然而，尚无研究考察瘦素和收缩对肌肉脂质代谢的刺激作用是否具有相加性。这是第一项在一系列收缩强度下，考察瘦素对离体氧化型肌肉脂质和碳水化合物（CHO）代谢直接影响的研究。我们研究了瘦素（10微克/毫升）对离体静止和收缩（2、8和20次强直收缩/分钟）的比目鱼肌中肌肉脂质池[磷脂（PL）、二酰甘油（DG）、三酰甘油（TG）]的合成与降解以及棕榈酸氧化的影响。在静止状态下，瘦素增加了脂肪酸氧化（+40%，P<0.05）和TG水解（+47%，P<0.05），同时减弱了TG酯化（-20%，P<0.05）。在有瘦素存在的情况下，静止时葡萄糖氧化未受影响。在强直收缩期间，脂肪酸氧化（+20 - 114%，P<0.05）、TG酯化（+19 - 33%，P<0.05）以及TG净利用率（+23%，P<0.05）均显著增加。然而，在收缩期间，瘦素对这些参数均无进一步影响。在收缩期间，瘦素未影响肌内糖原的净利用率以及葡萄糖氧化。本研究结果表明，瘦素对静止肌肉中的脂质代谢有重要影响，但对收缩期间的脂质代谢无影响。
