scholarly journals Comparison of the effects of dietary n−3 and n−6 polyunsaturated fatty acids on very-low-density lipoprotein secretion when delivered to hepatocytes in chylomicron remnants

2001 ◽  
Vol 357 (2) ◽  
pp. 481 ◽  
Author(s):  
Xiaozhong ZHENG ◽  
Michael AVELLA ◽  
Kathleen M. BOTHAM
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Secretion ◽  
Chylomicron Remnants

Comparison of the effects of dietary n−3 and n−6 polyunsaturated fatty acids on very-low-density lipoprotein secretion when delivered to hepatocytes in chylomicron remnants

2001 ◽  
Vol 357 (2) ◽  
pp. 481-487 ◽  
Author(s):  
Xiaozhong ZHENG ◽  
Michael AVELLA ◽  
Kathleen M. BOTHAM
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Fish Oil ◽  
Corn Oil ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Chylomicron Remnants

The effects of chylomicron remnants enriched in n-3 or n-6 polyunsaturated fatty acids (derived from fish or corn oil respectively) on the secretion of very-low-density lipoprotein (VLDL) lipid and apolipoprotein B (apoB) by rat hepatocytes in culture was investigated. Remnants were prepared in vivo from chylomicrons obtained from rats given an oral dose of fish or corn oil and incubated with cultured hepatocytes for up to 16h. The medium was then removed and the secretion of cholesterol and triacylglycerol into the whole medium or the ρ < 1.050g/ml fraction during the following 7–24h was determined. After exposure of the cells to fish-oil as compared with corn-oil remnants, secretion of both cholesterol and triacylglycerol into the whole medium was decreased by 25–35%, and secretion into the ρ < 1.050g/ml fraction was decreased by 20–25%. In addition, the levels of apoB48 found in the ρ < 1.050g/ml fraction were significantly lower in cells treated with fish-oil rather than corn-oil remnants, although the levels of apoB100 remained unchanged. The expression of mRNA for apoB, as determined by reverse-transcriptase PCR, however, was not significantly changed after exposure of the cells to both types of remnants. These results demonstrate that the effects of dietary n-3 polyunsaturated fatty acids in depressing hepatic VLDL secretion occur directly when they are delivered to the liver from the intestine in chylomicron remnants, and that the secretion, but not the synthesis, of apoB is targeted.

Comparison of the effects of dietary saturated, mono-unsaturated and polyunsaturated fatty acids on very-low-density lipoprotein secretion when delivered to hepatocytes in chylomicron remnant-like particles

2007 ◽  
Vol 35 (3) ◽  
pp. 440-441 ◽  
Author(s):  
I. Lopez-Soldado ◽  
M. Avella ◽  
K.M. Botham
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Olive Oil ◽  
Corn Oil ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Rat Hepatocytes ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Chylomicron Remnant

The effect of chylomicron remnant-like particles (CRLPs) enriched in saturated, mono-unsaturated or n−6 polyunsaturated fatty acids (derived from palm, olive or corn oil, respectively) on the secretion of VLDL (very-low-density lipoprotein) by rat hepatocytes in culture was investigated. CRLPs were incubated with cultured hepatocytes for 5 h. The medium was then removed and the secretion of cholesterol and triacylglycerol (TAG) into the whole medium during the following 16 h was determined. After exposure of the cells to olive oil as compared with corn and palm oil CRLPs, secretion of TAG into the medium was decreased. The TAG content of the cells was also lower in experiments with olive oil as compared with corn oil CRLPs. The levels of apoB48 (apolipoprotein B48) found in the medium remained unchanged after the exposure of the cells to the different types of remnants. These findings indicate that the type of fat in the diet directly affects VLDL lipid secretion on delivery to the liver in chylomicron remnants.

The Effects of Dietary n-3 Polyunsaturated Fatty Acids Delivered in Chylomicron Remnants on the Transcription of Genes Regulating Synthesis and Secretion of Very-Low-Density Lipoprotein by the Liver: Modulation by Cellular Oxidative State

2003 ◽  
Vol 228 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Kathleen M. Botham ◽  
Xiaozhong Zheng ◽  
Mariarosaria Napolitano ◽  
Michael Avella ◽  
Claudio Cavallari ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fish Oil ◽  
Corn Oil ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Vldl Secretion ◽  
Chylomicron Remnants ◽  
Oxidative State

The influence of chylomicron remnants enriched in n-3 or n-6 polyunsaturated fatty acids (PUFA) (derived from fish or corn oil, respectively) on the expression of mRNA for four genes Involved in the regulation of the synthesis, assembly, and secretion of very-low-density lipoprotein (VLDL) in the liver was investigated in normal rat hepatocytes and after manipulation of the cellular oxidative state by incubation with N-acetyl cysteine (NAC) or CuSO4. The four genes investigated were those encoding apolipoprotein B (apoB), the microsomal triacylglycerol transfer protein (MTP), and the enzymes acyl coenzyme A:diacylglycerol acyltransferase (DGAT) and acyl coenzyme A:cholesterol acyltransferase 2 (ACAT2), which play a role in the regulation of triacylglycerol and cholesteryl ester synthesis, respectively. mRNA levels for apoB, MTP, and DGAT were unaffected by either fish or corn oil chylomicron remnants, but the amount of ACAT2 mRNA was significantly reduced after Incubation of the hepatocytes with fish oil remnants as compared with corn oil remnants or without remnants. These findings indicate that the delivery of dietary n-3 PUFA to hepatocytes in chylomicron remnants downregulates the expression of mRNA for ACAT2, and this may play a role in their inhibition of VLDL secretion. However, when the cells were shifted into a prooxidizing or pro-reducing state by pretreatment with CuSO4 (1 mM) or NAC (5 mM) for 24 hr, levels of mRNA for MTP were increased by about 2- or 4-fold, respectively, by fish oil remnants, whereas corn oil remnants had no significant effect. Fish oil remnants also caused a smaller increase in apoB mRNA in comparison with com oil remnants in NAC-treated cells (+38%). These changes would be expected to lead to increased VLDL secretion rather than the decrease associated with dietary n-3 PUFA in normal conditions. These findings suggest that relatively minor changes in cellular redox levels can have a major influence on important liver functions such as VLDL synthesis and secretion.

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