Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Am J Physiol Endocrinol Metab. 2012 Nov 1;303(9):E1134-41. doi: 10.1152/ajpendo.00282.2012. Epub 2012 Sep 11.
Excess amounts of abdominal subcutaneous (SAT) and visceral (VAT) adipose tissue (AT) are associated with insulin resistance, even in normal-weight subjects. In contrast, gluteal-femoral AT (GFAT) is hypothesized to offer protection against insulin resistance. Dynamic PET imaging studies were undertaken to examine the contributions of both metabolic activity and size (volume) of these depots in systemic glucose metabolism. Nonobese, healthy volunteers (n = 15) underwent dynamic PET imaging uptake of [¹⁸F]FDG at a steady-state (20 mU·m⁻²·min⁻¹) insulin infusion. PET images of tissue [¹⁸F]FDG activity were coregistered with MRI to derive K values for insulin-stimulated rates of fractional glucose uptake within tissue. Adipose tissue volume was calculated from DEXA and MRI. VAT had significantly higher rates of fractional glucose uptake per volume than SAT (P < 0.05) or GFAT (P < 0.01). K(GFAT) correlated positively (r = 0.67, P < 0.01) with systemic insulin sensitivity [glucose disappearance rate (R(d))] and negatively with insulin-suppressed FFA (r = -0.71, P < 0.01). SAT (r = -0.70, P < 0.01) and VAT mass (r = -0.55, P < 0.05) correlated negatively with R(d), but GFAT mass did not. We conclude that rates of fractional glucose uptake within GFAT and VAT are significantly and positively associated with systemic insulin sensitivity in nonobese subjects. Furthermore, whereas SAT and VAT amounts are confirmed to relate to systemic insulin resistance, GFAT amount is not associated with insulin resistance. These dynamic PET imaging studies indicate that both quantity and quality of specific AT depots have distinct roles in systemic insulin resistance and may help explain the metabolically obese but normal-weight phenotype.
腹部皮下（SAT）和内脏（VAT）脂肪组织（AT）的过量与胰岛素抵抗有关，即使在正常体重的受试者中也是如此。相比之下，臀股部脂肪组织（GFAT）被认为可以预防胰岛素抵抗。进行了动态 PET 成像研究，以检查这些脂肪组织的代谢活性和大小（体积）对全身葡萄糖代谢的贡献。非肥胖、健康志愿者（n = 15）在稳定状态（20 mU·m⁻²·min⁻¹）胰岛素输注下进行了动态 PET 成像摄取 [¹⁸F]FDG。组织 [¹⁸F]FDG 活性的 PET 图像与 MRI 进行了核配准，以得出组织内胰岛素刺激的葡萄糖摄取分数的 K 值。使用 DEXA 和 MRI 计算脂肪组织体积。与 SAT（P < 0.05）或 GFAT（P < 0.01）相比，VAT 的葡萄糖摄取分数率明显更高。K(GFAT)与全身胰岛素敏感性呈正相关（r = 0.67，P < 0.01）[葡萄糖清除率（R(d)）]，与胰岛素抑制的 FFA 呈负相关（r = -0.71，P < 0.01）。SAT（r = -0.70，P < 0.01）和 VAT 质量（r = -0.55，P < 0.05）与 R(d)呈负相关，但 GFAT 质量与胰岛素抵抗无关。我们得出的结论是，非肥胖受试者中 GFAT 和 VAT 内的葡萄糖摄取分数率与全身胰岛素敏感性呈显著正相关。此外，尽管 SAT 和 VAT 量与全身胰岛素抵抗有关，但 GFAT 量与胰岛素抵抗无关。这些动态 PET 成像研究表明，特定 AT 储存库的数量和质量在全身胰岛素抵抗中具有独特的作用，并可能有助于解释代谢肥胖但体重正常的表型。
