Conjugated linoleic acids alter bone fatty acid composition and reduce ex vivo prostaglandin E₂ biosynthesis in rats fed n‐6 or n‐3 fatty acids

Abstract

This study evaluated the effects of conjugated linoleic acids (CLA) on tissue fatty acid composition and ex vivo prostaglandin E2 (PGE2) production in rats given diets varying in n-6 and n-3 fatty acids. Four groups of rats were given a basal semipurified diet (AIN-93G) containing 70 g/kg of added fat for 42 d. The fat treatments were formulated to contain CLA (0 vs. 10 g/kg of diet) and n-6 (soybean oil having an n-6/n-3 ratio of 7.3) and n-3 fatty acids (menhaden oil + safflower oil having an n-6/n-3 ratio of 1.8) in different ratios in a 2 x 2 factorial design. Fatty acids in liver, serum, muscle, heart, brain, spleen, and bone (cortical, marrow, and periosteum) were analyzed by capillary gas-liquid chromatography. The various dietary lipid treatments did not affect growth; however, CLA improved feed efficiency. The CLA isomers were found in all rat tissues analyzed although their concentrations varied. Dietary CLA decreased the concentrations of 16:1n-7, 18:1, total monounsaturates and n-6 fatty acids, but increased the concentrations of n-3 fatty acids (22:5n-3 and 22:6n-3), and saturates in the tissues analyzed. Ex vivo PGE2 production in bone organ culture was decreased by n-3 fatty acids and CLA. We speculate that CLA reduced the concentration of 18:1 fatty acids by inhibiting liver delta9-desaturase activity. The fact that CLA lowered ex vivo PGE2 production in bone organ culture suggests that these conjugated fatty acids have the potential to influence bone formation and resorption.

Effects of conjugated linoleic acid or betaine on the growth performance and fatty acid composition in backfat and belly fat of finishing pigs fed dried distillers grains with solubles

“…The lipids extracted from all of the samples were methylated (sodium methoxide) as described by Li and Watkins (1998): sample was dissolved in dry toluene (1 ml) in a capped test tube, 0.5 M sodium methoxide in anhydrous methanol (2 ml) was added, the solution was maintained at 50°C for 10 min, and glacial acetic acid (0.1 ml) was added followed by deionized water (5 ml). The fatty acid methyl esters (FAME) were extracted into hexane (2 × 3 ml) and dried over anhydrous sodium sulfate.…”

Feeding dried distillers grains with solubles to lactating beef cows: impact of excess protein and fat on cow performance, milk production and pre-weaning progeny growth

“…Fatty acid analysis Total lipid was extracted from milk with a solution of chloroform and methanol (2 : 1) according to the procedures of Folch et al (1957) and derivatized to fatty acid methyl esters according to Li and Watkins (1998). Fatty acid methyl ethers were analyzed by gas chromatography on a gas chromatograph (model 3900; Varian Inc., Palo Alto, CA, USA) equipped with a 30 m column (CP-WAX 52 CB; Varian Inc.) and a flame ionization detector.…”

Fatty acid analysis of wild ruminant tissues: evolutionary implications for reducing diet-related chronic disease

“…Fatty acid methyl esters (FAME) were prepared from the tissue lipids using boron trifluoride (BF 3 ) in methanol (14%, w=w; Supelco Inc., Bellefonte, PA, USA) following the procedure of Watkins et al, (1997). For quantification of conjugated linoleic acid (CLA) isomers, lipids extracted from tissue samples were methylated (sodium methoxide) following the method of Li and Watkins (1998). Lipids were dissolved in dry toluene (1 ml) in a test tube with a teflon-lined screw cap, 0.5 M sodium methoxide in anhydrous methanol (2 ml) added, the solution maintained at 50 C for 10 min, and glacial acetic acid (0.1 ml) added followed by deionized water (5 ml).…”