Comparison of lipid and fatty acid composition of the liver, subcutaneous and intra-abdominal adipose tissue, and serum.
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.
Kotronen
Anna
A
Department of Medicine, Division of Diabetes, Helsinki, Finland. anna.kotronen@helsinki.fi
Seppänen-Laakso
Tuulikki
T
Westerbacka
Jukka
J
Kiviluoto
Tuula
T
Arola
Johanna
J
Ruskeepää
Anna-Liisa
AL
Yki-Järvinen
Hannele
H
Oresic
Matej
M
D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D050152:Intra-Abdominal Fat / Q000737:chemistry*; D008055:Lipids / Q000032:analysis* / Q000097:blood*; D008099:Liver / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D050151:Subcutaneous Fat / Q000737:chemistry*
D008055:Lipids