Department of Medicine, Division of Diabetes, Helsinki, Finland.
Obesity (Silver Spring). 2010 May;18(5):937-44. doi: 10.1038/oby.2009.326. Epub 2009 Oct 1.
Ceramides may mediate saturated fat-induced insulin resistance, but there are no data comparing ceramide concentrations between human tissues. We therefore performed lipidomic analysis of human subcutaneous (SCfat) and intra-abdominal (IAfat) adipose tissue, the liver, and serum in eight subjects. The liver contained (nmol/mg tissue) significantly more ceramides (1.5-3-fold), sphingomyelins (7-8-fold), phosphatidylethanolamines (10-11-fold), lysophosphatidylcholines (7-12-fold), less ether-linked phosphatidylcholines (2-2.5-fold) but similar amounts of diacylglycerols as compared to SCfat and IAfat. The amounts of ceramides and their synthetic precursors, such as palmitic (16:0) free fatty acids and sphingomyelins, differed considerably between the tissues. The liver contained proportionally more palmitic, stearic (18:0), and long polyunsaturated fatty acids than adipose tissues. Stearoyl-CoA desaturase 1 (SCD1) activity reflected by serum, estimated from the 16:1/16:0-ratio, was closely related to that in the liver (r = 0.86, P = 0.024) but not adipose tissues. This was also true for estimated elongase (18:1/16:1, r = 0.89, P = 0.01), and Delta5 (20:4/20:3, r = 0.89, P = 0.012) and Delta6 (18:3[n-6]/18:2, r = 1.0, P < 0.001) desaturase activities. We conclude that the human liver contains higher concentrations of ceramides and saturated free fatty acids than either SCfat or IAfat.
神经酰胺可能介导饱和脂肪诱导的胰岛素抵抗，但目前尚无比较人体组织中神经酰胺浓度的相关数据。因此，我们对 8 名研究对象的皮下（SCfat）和内脏（IAfat）脂肪、肝脏和血清进行了脂质组学分析。与 SCfat 和 IAfat 相比，肝脏（nmol/mg 组织）中的神经酰胺（1.5-3 倍）、神经鞘磷脂（7-8 倍）、磷酸乙醇胺（10-11 倍）、溶血磷脂酰胆碱（7-12 倍）更多，醚连接的磷脂酰胆碱（2-2.5 倍）更少，但二酰甘油的含量相似。与其他组织相比，神经酰胺及其合成前体（如棕榈酸（16:0）游离脂肪酸和神经鞘磷脂）的含量差异较大。肝脏中饱和脂肪酸（如棕榈酸、硬脂酸（18:0）和长链多不饱和脂肪酸）的含量比例高于脂肪组织。通过血清中 16:1/16:0 比值估算的硬脂酰辅酶 A 去饱和酶 1（SCD1）活性与肝脏中的活性密切相关（r = 0.86，P = 0.024），但与脂肪组织无关。这也适用于估算的延伸酶（18:1/16:1，r = 0.89，P = 0.01）和 Delta5（20:4/20:3，r = 0.89，P = 0.012）和 Delta6（18:3[n-6]/18:2，r = 1.0，P < 0.001）去饱和酶活性。综上所述，与 SCfat 或 IAfat 相比，人类肝脏中的神经酰胺和饱和游离脂肪酸含量更高。
