Faculties of Pharmacy and Medicine, Universidad San Pablo-CEU, Madrid, Spain.
Lipid Metabolism Research Laboratory, IIS-Fundación Jiménez Díaz, Madrid, Spain.
J Clin Lipidol. 2019 Mar-Apr;13(2):301-307. doi: 10.1016/j.jacl.2019.01.006. Epub 2019 Jan 23.
The regulation of adipose tissue metabolism in early childhood obesity is not well understood. Insulin levels are higher and insulin resistance seems to be present in prepubertal children with obesity but, differing from their behavior in adults with obesity, non-esterified fatty acid (NEFA) concentrations are not increased. Retinol-binding protein (RBP)-4 concentration is associated with obesity and insulin resistance conditions, but the means of this relationship remain unclear, and few studies have taken retinol values into account to evaluate it.
To analyze the relationship between RBP4 concentration and lipolytic products in plasma in 141 prepubertal children aged 6 to 8 years, with and without obesity.
Plasma glucose, insulin, triacylglycerols, NEFA, glycerol, leptin, RBP4, and retinol were analyzed in obese and in their normal-weight counterparts. Homeostatic model assessment, quantitative insulin sensitivity check index, and fasting glucose to insulin ratio were calculated as indicators of insulin resistance.
Fasted plasma NEFA concentrations were lower in children with obesity than in their normal weight counterparts, despite leptin, insulin resistance indices, RBP4, retinol, and RBP4/retinol (an index of free-RBP4) being higher. NEFA and glycerol concentrations were inversely correlated with RBP4/retinol in children with obesity but not in those without obesity. In normal weight children, total RBP4 correlated negatively with NEFA and glycerol concentrations and positively with insulin and homeostasis model assessment for insulin resistance. These results indicate that a low saturation of RBP4 with retinol, which implies a higher concentration of free-RBP4, may preserve the antilipolytic function of insulin in adipose tissue in children with obesity.
Our findings suggest that, in prepubertal children with obesity and insulin resistance, the amount of RBP4/retinol correlates with the antilipolytic response of the adipose tissue to insulin rather than the total RBP4 concentration.
儿童肥胖症早期脂肪组织代谢的调节机制尚不清楚。肥胖的青春期前儿童胰岛素水平较高，似乎存在胰岛素抵抗，但与肥胖成人的行为不同，非酯化脂肪酸（NEFA）浓度并未升高。视黄醇结合蛋白 4（RBP-4）浓度与肥胖和胰岛素抵抗有关，但这种关系的机制尚不清楚，且很少有研究考虑视黄醇值来评估它。
分析 141 名 6 至 8 岁肥胖和非肥胖青春期前儿童的 RBP4 浓度与血浆脂解产物之间的关系。
分析肥胖儿童和体重正常儿童的血浆葡萄糖、胰岛素、三酰甘油、NEFA、甘油、瘦素、RBP4 和视黄醇。稳态模型评估、定量胰岛素敏感性检查指数和空腹血糖与胰岛素比值作为胰岛素抵抗的指标。
尽管肥胖儿童的瘦素、胰岛素抵抗指数、RBP4、视黄醇和 RBP4/视黄醇（游离 RBP4 指数）较高，但他们的空腹血浆 NEFA 浓度低于体重正常的儿童。肥胖儿童的 NEFA 和甘油浓度与 RBP4/视黄醇呈负相关，但非肥胖儿童则无此相关性。在体重正常的儿童中，总 RBP4 与 NEFA 和甘油浓度呈负相关，与胰岛素和胰岛素抵抗的稳态模型评估呈正相关。这些结果表明，RBP4 与视黄醇的结合程度低，意味着游离 RBP4 浓度较高，可能会保护肥胖儿童脂肪组织中胰岛素的抗脂解作用。
我们的研究结果表明，在肥胖和胰岛素抵抗的青春期前儿童中，RBP4/视黄醇的量与脂肪组织对胰岛素的抗脂解反应相关，而与总 RBP4 浓度无关。
