Lipid Metabolism in Endotoxic Rats

Abstract

Studies were conducted to investigate the effect of E. coli endotoxin administration on hepatic triglyceride lipase (H-TGL) activity in rats, since H-TGL activity is known to behave differently from lipoprotein lipase (LPL) activity in various situations. Plasma triglyceride and free fatty acid concentrations were markedly elevated in animals after injection of endotoxin. Cholesterol and phospholipids were also increased significantly. Lipoprotein analysis by ultracentrifugation showed that the most pronounced increase of lipoproteins was in the VLDL and IDL fractions. Triglyceride lipase activities in post-heparin plasma were markedly decreased. A selective assay for H-TGL activity using a specific antibody revealed that this enzyme as well as LPL is significantly decreased (26% of control) in endotoxic animals. Thus, the increase of VLDL and IDL appears to result from the decrease of both of LPL and H-TGL.

Regulation of hepatic lipase activity by sphingomyelin in plasma lipoproteins

“…Since the activity of HL is known to be inversely correlated with the plasma HDL levels [2] the study of factors which regulate HL activity is important in understanding the regulation of HDL metabolism. Whereas the regulation of HL transcription, synthesis and secretion from the liver have been well studied [1,6–8], the physiological factors that regulate its activity in the plasma compartment are not well understood. Furthermore, while it is known that HL acts preferentially on HDL compared to VLDL and LDL [4], the reason for this specificity is unknown, since it does not require an apoprotein cofactor for its activity.…”

Endotoxin suppresses rat hepatic: Low density lipoprotein receptor expression

“…Administration of endotoxin results in profound effects on the metabolism of plasma lipoproteins. Thus, hyperlipidaemia occurs in endotoxin-treated animals ( [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], reviewed in [18,19]) and during infections with Gram-negative bacteria, parasites, or viruses [20][21][22][23][24][25][26][27][28]. Plasma triacylglycerols are increased in endotoxin-treated animals.…”

Endotoxin and cytokines decrease serum levels and extra hepatic protein and mRNA levels of cholesteryl ester transfer protein in syrian hamsters.

“…The activity of hepatic lipase is decreased by endotoxin and inflammation (7)(8)(9)(10). Hepatic lipase is responsible for metabolizing large triglyceride-rich HDL into smaller HDL 2 , which is more rapidly cleared from the circulation, and to pre ␤ 1 HDL, which is believed to play a key role in mediating the transfer of free cholesterol from cell membranes (11)(12)(13).…”