Dietary Fat Composition Influences Tissue Lipid Profile and Gene Expression in Fischer‐344 Rats

Abstract

The AIN-76A diet causes fatty liver in rodents when fed for long periods of time. The aim of this study was to utilize fatty acid analysis and transcriptomics to investigate the effects of different fat sources in the AIN-76A diet on tissue lipid profiles and gene expression in male, weanling Fischer-344 rats. Animals were fed isocaloric diets that differed only in the fat source: (1) corn oil (CO) (2) anhydrous milk fat (AMF), and (3) AMF supplemented with 10% phospholipids from the milk fat globule membrane (AMF-MFGM). There were no differences in food intake, body weight, growth rate, or body fat composition among the groups, and the fatty acid compositions of red blood cells (RBC), plasma, muscle, and visceral adipose tissues reflected the dietary fat sources. Modifying the fat source resulted in 293 genes differentially regulated in skeletal muscle, 1,124 in adipose, and 831 in liver as determined by analysis of variance (ANOVA). Although tissue fatty acid profiles mostly reflected the diet, there were several quantitative differences in lipid classes in the liver and plasma. The AMF diet resulted in the highest level of hepatic triacylglycerols, but the lowest level in plasma. The CO diet resulted in significant accumulation of hepatic unesterified fatty acids and decreased DGAT expression and activity, a potential trigger for steatohepatitis. These results indicate that the fatty acid composition and presence of polar lipids in the AIN-76A diets have significant effects on lipid partitioning, gene expression, and potentially the development of liver pathology.

Potential role of milk fat globule membrane in modulating plasma lipoproteins, gene expression, and cholesterol metabolism in humans: a randomized study

“…The results from our current study are in accord with previous animal studies that showed fewer adverse effects on plasma lipids by MFGM or its components (17)(18)(19)(20)(21)(22) than with other milk fats. Note that the current differences between the 2 milkfat diets in regard to lipoprotein response occurred despite high intakes of SFA.…”

“…Some of these effects have also been associated with hepatic accumulation of phospholipids (33). Besides the effects on hepatic gene expression, milk phospholipids also seem to effect the partitioning of lipids in classes both within and between organs (17). Although data from the current study did not show a differential effect on plasma cholesterol mediated by differences in cholesterol synthesis or absorption, as assessed by the surrogate markers lathosterol, sitosterol, and campesterol, this possibility cannot be excluded until more-direct measurements in humans have been performed.…”

“…Bovine MFGM consists of w70% lipids and w20% proteins (16). Animal studies showed that MFGM and sphingolipids could lower plasma cholesterol partly by modulating hepatic gene expression (17)(18)(19)(20)(21)(22). The content and physical structure of MFGM are differentially preserved in dairy products.…”

Liver phospholipids fatty acids composition in response to different types of diets in rats of both sexes

“…Consumption of fish oil significantly increased EPA and n-3 docosapentaenoic acid (DPA) in liver PL of male rats [6]. On the other side, the milk-fat-based diet which had both, significant contributions of saturated fatty acids (SFA) and low PUFA content, also reflected on plasma and tissue FA composition in rats [7]. …”

Milk Polar Lipids Affect In Vitro Digestive Lipolysis and Postprandial Lipid Metabolism in Mice

“…In mice, 2 wt% of a ''dairy PL-rich extract'' (containing PLs as a milk fat globule membrane isolate), added to a 21 wt% fat diet containing 0.15 wt% cholesterol, reduced liver and plasma lipids (14). Rats fed during 12 wk with an anhydrous milk fat diet supplemented with 10% of MPLs, compared with an anhydrous milk fat diet only, had more plasma TGs and PLs but less hepatic cholesterol esters (15). Moreover, 2 studies investigated the ability of milk sphingomyelin to inhibit intestinal absorption of cholesterol (16,17).…”