讓脂肪細胞變活躍：白脂褐化的生理意義與應用

Activate your adipocytes: the physical relevance and applications of browning of white adipose tissue

陳思涵(Szu-Han Chen) ； 趙蓓敏(Pei-Min Chao)

《台灣營養學會雜誌》 44卷4期 (2020/12) Pp. 127-140

https://doi.org/10.6691/NSJ.202012_44(4).0003

摘要

肥胖與併發症盛行，科學家致力尋找對策，近來備受矚目的是白脂褐化在抗肥胖的應用。不同於白色脂肪組織主司能量庫存，棕色脂肪組織主司生熱並能促進能量支出。由^(18)F-FDG正子電腦斷層造影（^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography scan，^(18)F-FDG PET/CT scan）顯示成人體內仍具有（類）棕色脂肪組織，活性及數量因人而異。現今發現有一群存在於白色脂肪組織中可被誘導的米色脂肪細胞，源起不同於傳統棕或傳統白色脂肪細胞，也能表現UCP1促進生熱。在無外界刺激下米色脂肪細胞偽裝自己與白色脂肪細胞無異，透過冷、（正）腎上腺素或飲食因子刺激，轉變成具有米色脂肪細胞表型並有大量生熱基因表現，稱為白脂褐化。不論人體生理（季節）、病理（如嗜鉻細胞瘤、惡病質及燒燙傷）、基因轉殖還是藥物處理動物模式之白脂褐化，皆指向加速葡萄糖與脂肪酸的異化分解，可應用於改善肥胖、糖尿病及脂肪肝。新生小鼠有短暫自發白脂褐化現象，但目前代表的生理意義仍未清楚，包括是否可用於預測成年誘發白脂褐化能力，針對新生階段的白脂褐化是否可操弄及後續生理意義是一有趣值得探討的議題。

關鍵字

白脂褐化 ； 生熱作用 ； 肥胖 ； 米色脂肪細胞

並列摘要

Due to the global escalating rate and its comorbidities, researchers put great efforts on finding solutions to combat obesity. Recently, the browning of white adipose tissue (WAT) turns out to be an appealing strategy. In contrast to WAT serve as energy storage sites, brown adipose tissues function in thermogenesis, thus contributing to energy expenditure. Using ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography scan, the presence of brown (or brown-like) adipose tissue in adult human has been evidenced, though its amount and activity varied greatly among individuals. With distinct lineage from the traditional white or traditional brown fat cells, a third type of fat cells (i.e. beige cells), which is inducible, capable in expressing UCP1, and competent in thermogenesis, was found in the WAT. These cells are morphologically indistinguishable from the white fat cells at basal status. Upon stimulated by cold, (nor)adrenaline or dietary factors, these cells show their identity through morphological transformation and expression of thermogenic genes; a process called WAT browning. No matter occurred physiologically or pathologically in human or genetically or pharmacologically manipulated mice, all consistently indicate that WAT browning increases catabolism of glucose and fatty acids, thus having potentials in anti-obesity, anti-diabetes and anti-steatosis. A fascinating phenomenon is a transient and spontaneous WAT browning apparent in neonatal mice, which seems to be a predictor for the WAT browning ability at adulthood. Whether WAT browning at this early stage is manipulatable and consequently benefits the future metabolic health is an interesting but remains mostly unknown issue waiting to be explored.

並列關鍵字

browning of white adipose tissue ； thermogenesis ； obesity ； brite cells