Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Obesity (Silver Spring). 2012 May;20(5):972-7. doi: 10.1038/oby.2011.355. Epub 2011 Dec 15.
Excessive metabolism of glucose and/or fatty acids may impair insulin signaling by increasing oxidative stress. The objective of this study was to examine the association between insulin sensitivity and protein carbonyls, a systemic marker of oxidative stress, in healthy, nondiabetic women, and to determine if the relationship differed with race. Subjects were 25 African-Americans (AA, BMI 28.4 ± 6.2 kg/m(2), range 18.8-42.6 kg/m(2); age 33.1 ± 13.5 years, range 18-58 years) and 28 European-Americans (EA, BMI 26.2 ± 5.9 kg/m(2), range 18.7-48.4 kg/m(2); age 31.6 ± 12.4 years, range 19-58 years). Insulin sensitivity was determined using an intravenous glucose tolerance test incorporating [6,6-(2)H(2)]-glucose, and a two-compartment mathematical model. Multiple linear regression results indicated that insulin sensitivity was inversely associated with protein carbonyls in AA (standardized regression coefficient -0.47, P < 0.05) but not EA (0.01, P = 0.945), after adjusting for %body fat. In contrast, %body fat was significantly and positively associated with insulin sensitivity in EA (-0.54, P < 0.01) but not AA (-0.24, P = 0.196). Protein carbonyls were associated with free fatty acids (FFA) in AA (r = 0.58, P < 0.01) but not EA (r = -0.11, P = 0.59). When subjects were divided based on median levels of fasting glucose and FFA, those with higher glucose/FFA concentrations had a significantly greater concentration of circulating protein carbonyls compared to those with lower glucose/FFA concentrations (P < 0.05). These results suggest that oxidative stress independently contributes to insulin sensitivity among AA women. Further, this association in AA may be mediated by circulating FFA and/or glucose.
葡萄糖和/或脂肪酸的过度代谢可能通过增加氧化应激来损害胰岛素信号。本研究的目的是在健康的非糖尿病女性中检查胰岛素敏感性与蛋白质羰基（一种全身性氧化应激标志物）之间的关系，并确定这种关系是否因种族而异。研究对象为 25 名非裔美国人（AA，BMI 为 28.4 ± 6.2 kg/m²，范围为 18.8-42.6 kg/m²；年龄 33.1 ± 13.5 岁，范围为 18-58 岁）和 28 名欧洲裔美国人（EA，BMI 为 26.2 ± 5.9 kg/m²，范围为 18.7-48.4 kg/m²；年龄 31.6 ± 12.4 岁，范围为 19-58 岁）。使用包含 [6,6-（2）H（2）]-葡萄糖的静脉葡萄糖耐量试验和双室数学模型来确定胰岛素敏感性。多元线性回归结果表明，在调整了体脂肪百分比后，AA 中胰岛素敏感性与蛋白质羰基呈负相关（标准化回归系数 -0.47，P < 0.05），而 EA 中则没有（0.01，P = 0.945）。相比之下，体脂肪百分比与 EA 中的胰岛素敏感性呈显著正相关（-0.54，P < 0.01），而与 AA 中的胰岛素敏感性则没有相关性（-0.24，P = 0.196）。AA 中的蛋白质羰基与游离脂肪酸（FFA）相关（r = 0.58，P < 0.01），而 EA 中则没有相关性（r = -0.11，P = 0.59）。当根据空腹血糖和 FFA 的中位数将受试者进行分组时，那些血糖/FFA 浓度较高的人比那些血糖/FFA 浓度较低的人循环蛋白质羰基的浓度明显更高（P < 0.05）。这些结果表明，氧化应激独立于 AA 女性的胰岛素敏感性。此外，AA 中的这种关联可能是由循环 FFA 和/或葡萄糖介导的。
