1 Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts.
Metab Syndr Relat Disord. 2014 Feb;12(1):56-61. doi: 10.1089/met.2013.0100. Epub 2013 Nov 19.
Mitochondrial dysfunction plays a role in the development of muscle insulin resistance (IR) and the accumulation of intramyocellular lipid (IMCL) in skeletal muscle that can, in turn, interfere with insulin signaling. The purpose of this study was to assess mitochondrial function (MF) and IMCL in obese adolescent girls with and without IR to determine whether: (1) Girls with IR have impaired MF, and (2) impaired MF in girls with IR is related to higher IMCL.
We examined 22 obese girls aged 13-21 years old for IR [defined as a homeostasis model assessment of insulin resistance (HOMA-IR) value >4. Phosphorus magnetic resonance spectroscopy (31P-MRS) and proton magnetic resonance spectroscopy (1H-MRS), respectively, were used to determine MF and IMCL of the soleus muscle along with magnetic resonance imaging (MRI) measures of visceral, subcutaneous, and total adipose tissue (VAT, SAT, and TAT) in girls with HOMA-IR >4 (insulin-resistant group) versus HOMA-IR ≤ 4 (insulin-sensitive group). Serum lipids and waist-to-hip ratio (W/H) were also measured.
Girls with IR (n=8) did not differ from the insulin-sensitive group (n=14) for age, bone age, weight, VAT, SAT, TAT, or IMCL. However, the insulin-resistant group had higher W/H. Additionally the insulin-resistance group had a lower log rate of postexercise phosphocreatine (PCr) recovery (ViPCr) and a higher log PCr recovery constant (tau), indicative of impaired MF.
Obese girls with increased IR have impaired mitochondrial function. This association is not mediated by alterations in IMCL or adipose tissue. Further studies are necessary to determine whether there is a causal relation between impaired mitochondrial function and IR in obesity and mediators of such a relationship.
线粒体功能障碍在肌肉胰岛素抵抗（IR）的发展和骨骼肌中细胞内脂质（IMCL）的积累中起作用，这反过来又会干扰胰岛素信号。本研究的目的是评估肥胖青少年女孩中存在和不存在 IR 的情况下的线粒体功能（MF）和 IMCL，以确定：（1）存在 IR 的女孩是否存在 MF 受损，以及（2）存在 IR 的女孩的 MF 受损是否与更高的 IMCL 相关。
我们对 22 名年龄在 13-21 岁的肥胖女孩进行了 IR 检查[定义为稳态模型评估的胰岛素抵抗（HOMA-IR）值>4。磷磁共振波谱（31P-MRS）和质子磁共振波谱（1H-MRS）分别用于确定 HOMA-IR >4（胰岛素抵抗组）的比目鱼肌的 MF 和 IMCL，以及磁共振成像（MRI）测量的内脏、皮下和总脂肪组织（VAT、SAT 和 TAT），与 HOMA-IR≤4（胰岛素敏感组）的女孩进行比较。还测量了血清脂质和腰臀比（W/H）。
IR 组（n=8）与胰岛素敏感组（n=14）在年龄、骨龄、体重、VAT、SAT、TAT 或 IMCL 方面没有差异。然而，胰岛素抵抗组的 W/H 更高。此外，胰岛素抵抗组的运动后磷酸肌酸（PCr）恢复的对数速率（ViPCr）较低，PCr 恢复常数（tau）较高，表明 MF 受损。
IR 增加的肥胖女孩存在线粒体功能障碍。这种关联不受 IMCL 或脂肪组织变化的影响。需要进一步的研究来确定肥胖中存在的线粒体功能障碍与 IR 之间是否存在因果关系，以及这种关系的中介因素。
