Acute modulation of rat hepatic lipid metabolism by sulphur-substituted fatty acid analogues.
A single oral dose of two 3-thia (3-thiadicarboxylic and tetradecylthioacetic acids) and of 4-thia (tetradecylthiopropionic acid) fatty acids were administered to normolipidemic rats and their effects on lipid metabolism over a 24 hr period were studied. All three thia fatty acids could be detected in plasma 2 hr after treatment. Tetradecylthioacetic and tetradecylthiopropionic acids were detected in different hepatic lipid fractions but were incorporated mainly into hepatic phospholipids. Two hours after administration hepatic mitochondrial beta-oxidation and the total liver level of long-chain fatty acyl-CoA increased with a concomitant decrease in saturated fatty acids, total hepatic malonyl-CoA and plasma triacylglycerol levels in the 3-thia fatty acid groups. Tetradecylthiopropionic acid administration caused a decrease in mitochondrial beta-oxidation and an increase in plasma triacylglycerol at 24 hr. The activities of key lipogenic enzymes were unaffected in all treatment groups. Plasma cholesterol level was reduced only at 8 hr in 3-thiadicarboxylic acid treated rats although 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase was suppressed already at 2, 4, 8 and 12 hr. The results show that thia fatty acids are rapidly absorbed and are systemically available after oral administration but the 3-thia fatty acids reached systemic circulation more slowly and less completely than the 4-thia fatty acid. Very low levels of the thia fatty acids are detected in plasma 24 hr after a single administration. They are incorporated into all hepatic lipid classes, especially phospholipids. Rapid incorporation of a non beta-oxidizable thia fatty acid into hepatic lipids may cause a diversion of other fatty acids from glycerolipid biosynthesis to mitochondrial beta-oxidation. Stimulation of mitochondrial beta-oxidation and suppression of HMG-CoA reductase are primary events, occurring within hours, after 3-thia fatty acid administration. The hypotriglyceridemic effect of the 3-thia fatty acids observed at 2-4 hr is independent of the activities of key lipogenic and triacylglycerol synthesising enzymes.
Asiedu
D K
DK
Institute of Clinical Biology, University of Bergen, Haukeland University Hospital, Norway.
Demoz
A
A
Skorve
J
J
Grav
H J
HJ
Berge
R K
RK
D000818:Animals; D003998:Dicarboxylic Acids / Q000097:blood; D004790:Enzyme Induction; D005227:Fatty Acids / Q000494:pharmacology*; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D011422:Propionates / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D013440:Sulfides / Q000097:blood; D013456:Sulfur Acids / Q000494:pharmacology*; D014280:Triglycerides / Q000097:blood
D003998:Dicarboxylic Acids; D005227:Fatty Acids; D008055:Lipids; D011422:Propionates; D013440:Sulfides; D013456:Sulfur Acids; D014280:Triglycerides; C062077:1-(carboxyethylthio)tetradecane; C062079:1,10-bis(carboxymethylthiodecane); C062078:1-(carboxymethylthio)tetradecane