Pituitary Research Unit, Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia.
J Clin Endocrinol Metab. 2011 Aug;96(8):2450-5. doi: 10.1210/jc.2011-0487. Epub 2011 May 25.
Positron emission tomography (PET)-computed tomography (CT) has identified metabolically active supraclavicular fat in adult humans based on uptake of labeled glucose and confirmed to be brown adipose tissue (BAT) histologically. However, PET-CT has estimated a prevalence of BAT as low as 5% in adult humans, casting doubt on its significance. The true prevalence of BAT is unknown because of the suboptimal sensitivity of standard PET-CT.
The objective of the study was to determine whether BAT is present in PET-negative supraclavicular fat.
This was a prospective cohort study.
The study was conducted at a tertiary referral hospital.
Seventeen patients who underwent preoperative PET-CT for staging of head and neck malignancy participated in the study.
The main outcome was signature BAT gene transcripts and protein in biopsies of supraclavicular fat with sc fat as negative control.
PET-CT was positive in three and negative in 14 patients. PET-positive fat harbored multilobulated lipid droplets and stained strongly for uncoupling protein 1 (UCP1). These features are absent in sc fat. By contrast, PET-negative fat contained a predominance of cells with unilobulated lipid droplets, with scattered cells containing multilobulated lipid droplets and variable UCP1 staining. Molecular analyses of fat biopsies showed lower but clear expression of UCP1, NDUFS3 (NADH dehydrogenase (ubiquinone) iron-sulfur protein 3), β₃-adrenoceptor, and PRDM16 (PR domain containing 16) transcripts.
BAT is present in supraclavicular fat, regardless of PET status. BAT is highly prevalent in adult humans, and its abundance determines PET status.
正电子发射断层扫描（PET）-计算机断层扫描（CT）根据标记葡萄糖的摄取，在成人中识别出代谢活跃的锁骨上脂肪，并通过组织学证实为棕色脂肪组织（BAT）。然而，PET-CT 估计成人 BAT 的患病率低至 5%，这对其意义提出了质疑。由于标准 PET-CT 的灵敏度不理想，BAT 的真实患病率尚不清楚。
本研究旨在确定 BAT 是否存在于 PET 阴性锁骨上脂肪中。
这是一项前瞻性队列研究。
该研究在一家三级转诊医院进行。
17 名患者因头颈部恶性肿瘤分期而行术前 PET-CT 检查，参与了这项研究。
主要结果是锁骨上脂肪活检中 BAT 特征性基因转录本和蛋白，锁骨上脂肪作为阴性对照。
14 例患者 PET-CT 阳性，3 例患者 PET-CT 阴性。PET 阳性脂肪含有多叶状脂滴，并强烈染色 UCP1（解偶联蛋白 1）。这些特征在 sc 脂肪中不存在。相比之下，PET 阴性脂肪中含有较多的单叶状脂滴细胞，散在的细胞含有多叶状脂滴和可变的 UCP1 染色。脂肪活检的分子分析显示 UCP1、NDUFS3（NADH 脱氢酶（泛醌）铁硫蛋白 3）、β₃-肾上腺素能受体和 PRDM16（PR 结构域包含 16）转录本的表达较低，但仍清晰。
无论 PET 状态如何，BAT 均存在于锁骨上脂肪中。BAT 在成人中普遍存在，其丰度决定了 PET 状态。
