Alteration of some inflammatory biomarkers by dietary oxysterols in rats.

Oxysterols are structurally similar to cholesterol, but are characterized by one or more additional oxygen-containing functional groups. These compounds are implicated in inflammation given their ability to cause irreversible damage to vascular cells. The aim of this study was to study the alteration of some inflammatory biomarkers in Wistar rats in response to dietary oxysterols. Eighteen rats were randomly divided into three groups of six rats each. A standard diet supplemented with 1% (w/w) pure cholesterol (Chol group) or 1% (w/w) of an oxidized cholesterol mixture (COPs group) was fed for 8 weeks. Blood serum was separated; abdominal, pericardial, and epididymal adipose tissue was removed carefully. The COPs subjects exhibited significant increase in blood pressure and serum triacylgycerols as well as increased body fat index and pericardic, abdominal, and epididymal adipose tissue. These effects were accompanied by elevated circulating levels of plasma high-sensitivity C-reactive protein, tumor necrosis factor alpha, and resistin. We suggest that dietary oxysterols have an important pro-inflammatory effect.

Dietary n-3 polyunsaturated fatty acids modify fatty acid composition in hepatic and abdominal adipose tissue of sucrose-induced obese rats.

The fatty acid profile of hepatocytes and adipocytes is determined by the composition of the dietary lipids. It remains unclear which fatty acid components contribute to the development or reduction of insulin resistance. The present work examined the fatty acid composition of both tissues in sucrose-induced obese rats receiving fish oil to determine whether the effect of dietary (n-3) polyunsaturated fatty acids (PUFAs) on the reversion of metabolic syndrome in these rats is associated to changes in the fatty acid composition of hepatocyte and adipocyte membrane lipids. Animals with metabolic syndrome were divided into a corn-canola oil diet group and a fish oil diet group, and tissues fatty acids composition were analyzed after 6 weeks of dietary treatment. Fatty acid profiles of the total membrane lipids were modified by the fatty acid composition of the diets fed to rats. N-3 PUFAs levels in animals receiving the fish oil diet plus sucrose in drinking water were significantly higher than in animals under corn-canola oil diets. It is concluded that in sucrose-induced obese rats, consumption of dietary fish oil had beneficial effects on the metabolic syndrome and that such effects would be conditioned by the changes in the n-3 PUFAs composition in hepatic and adipose tissues because they alter membrane properties and modify the type of substrates available for the production of active lipid metabolites acting on insulin resistance and obesity.

Effect of conjugated linoleic acid on body fat, tumor necrosis factor alpha and resistin secretion in spontaneously hypertensive rats.

Conjugated linoleic acid (CLA) is a naturally occurring group of dienoic derivaties of linoleic acid found mainly in beef and dairy products. CLA has been reported to reduce body fat, as well as to possess anticarcinogenic, antiatherogenic and procatabolic activities in animals. The objective of this study was to evaluate the effect of CLA supplementation to spontaneously hypertensive rats (SHR) on body fat, biochemical parameters of serum related tumor necrosis factor alpha (TNF-alpha) and resistin secretion. Thirty rats were divided in three groups, the first group of spontaneously hypertensive rats received a standard diet (V-SHR group, n=10), a second group of SHR was fed 1.5% of conjugated linoleic acid (CLA-SHR group, n=10) and the third was the control, non-hypertensive group (KW, n=10) also on a standard diet including 7.5% of sunflower oil during eight weeks. After CLA diet administration, spontaneously hypertensive rats showed a significant reduction in blood pressure, serum glucose, cholesterol and triacylglycerols, together with reduction of index of body fat, pericardic, abdominal and epididymal adipose tissue. These effects were accompanied by a decrease in the secretion of TNF-alpha and resistin.

Induction of Cd36 expression elicited by fish oil PUFA in spontaneously hypertensive rats.

Cd36 is an integral membrane glycoprotein expressed on the surface of cells active in fatty acid metabolism (adipocytes, muscle cells, platelets, monocytes, heart and intestine cells). This protein plays diverse functions including uptake of long-chain fatty acids and oxidized low-density lipoproteins. A recent report demonstrates that Cd36 deficiency underlies insulin resistance, defective fatty acid metabolism and hypertriglyceridemia in spontaneously hypertensive rats (SHRs). Cd36 is a tightly regulated protein whose expression is modulated through peroxisome proliferator-activated receptor (PPAR) transcription factors, by conditions that alter lipid metabolism such as diabetes mellitus and high-fat feeding. The purpose of this study was to evaluate the effect of dietary fish oil, rich in n-3 polyunsaturated fatty acids (PUFAs), on metabolic parameters and on the expression levels of Cd36 in adipose tissue in the SHR. Spontaneously hypertensive rats showed lower Cd36 mRNA levels when compared to Kyoto-Wistar (KW) rats (control). After 6 weeks of fish oil (FO) administration, this group of SHRs (FO-SHR) presented increased levels of Cd36 mRNA, concomitantly with decreased insulin, free fatty acids (FFAs), triglycerides, cholesterol, LDL, HDL, total lipids and blood pressure, in comparison to control rats that received a corn-canola oil diet. The study confirmed the beneficial effects of fish oil administration on the metabolic syndrome, suggesting that the induction of Cd36 expression could be one of the molecular mechanisms elicited by fish oil PUFAs.