Human Performance Laboratory, The College of Health & Human Performance, East Carolina University, Greenville, North Carolina, USA.
Obesity (Silver Spring). 2012 Jun;20(6):1174-8. doi: 10.1038/oby.2011.91. Epub 2011 Apr 14.
Mounting evidence suggests there is a reduced mobilization of stored fat in obese compared to lean women. It has been suggested that this decreased lipid mobilization may lead to, or perpetuate, the obese state; however, there may be a beneficial effect of reduced lipolysis, either by allowing for a sink of excess fatty acids, or by limiting a potentially harmful rise in interstitial and circulating fatty acid concentration. Nitric oxide (NO) may be responsible for a portion of the reduced in vivo rates of lipolysis in obese women because NO reduces adipose tissue lipolysis and adipose tissue nitric oxide synthase (NOS) mRNA is higher in obese than lean individuals. The purpose of this study was to determine if the inhibition of NOS by L-N(g)-monomethyl-L-arginine (L-NMMA) in the absence and presence of lipolytic stimulation would result in a larger increase in lipolytic rate in obese (OB) than lean (LN) women. Microdialysis probes were inserted into the subcutaneous abdominal adipose tissue of seven obese and six lean women to monitor lipolysis. Dialysate glycerol concentration increased in response to L-NMMA in OB (basal 125 ± 26 µmol/l; L-NMMA 225 ± 35 µmol/l) to a greater extent than in LN (basal 70 ± 18 µmol/l; L-NMMA 84 ± 20 µmol/l) women (P < 0.05). Dialysate glycerol increased to a similar extent in OB and LN in response to adrenergic stimulation by isoprenaline or norepinephrine in the presence of L-NMMA. The differential glycerol responses to L-NMMA between obese and lean could not be explained by differential blood flow responses. It can be concluded that NO suppresses basal lipolysis in obese women to a greater extent than in lean women.
越来越多的证据表明，与瘦人相比，肥胖者储存脂肪的动员减少。有人认为，这种脂质动员减少可能导致或维持肥胖状态；然而，脂肪分解减少可能有有益的效果，无论是通过提供多余脂肪酸的汇，还是通过限制间质和循环脂肪酸浓度的潜在有害升高。一氧化氮 (NO) 可能是肥胖女性体内脂肪分解率降低的部分原因，因为 NO 降低脂肪组织脂肪分解，并且肥胖个体的脂肪组织一氧化氮合酶 (NOS) mRNA 高于瘦个体。本研究的目的是确定在不存在和存在脂肪分解刺激的情况下，NOS 的抑制（用 L-N（g）-单甲基-L-精氨酸（L-NMMA））是否会导致肥胖（OB）女性的脂肪分解率增加幅度大于瘦（LN）女性。将微透析探针插入肥胖（OB）和瘦（LN）女性的腹部皮下脂肪组织中，以监测脂肪分解。与 LN 女性（基础 125 ± 26 µmol/l；L-NMMA 225 ± 35 µmol/l）相比，OB 女性（基础 125 ± 26 µmol/l；L-NMMA 225 ± 35 µmol/l）的透析液甘油浓度在 L-NMMA 作用下增加幅度更大（P < 0.05）。在 L-NMMA 存在下，通过异丙肾上腺素或去甲肾上腺素刺激肾上腺素能，OB 和 LN 女性的透析液甘油均增加到相似程度。OB 和 LN 女性对 L-NMMA 的甘油反应差异不能用血流反应的差异来解释。可以得出结论，NO 对肥胖女性的基础脂肪分解的抑制作用大于瘦女性。
