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.
Department of Medicine, Division of Diabetes, Helsinki, Finland. anna.kotronen@helsinki.fi
Anna
A
Kotronen
Tuulikki
T
Seppänen-Laakso
Jukka
J
Westerbacka
Tuula
T
Kiviluoto
Johanna
J
Arola
Anna-Liisa
AL
Ruskeepää
Hannele
H
Yki-Järvinen
Matej
M
Oresic
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