Effects of moderate fat intake with different n-3 fatty acid sources and n-6/n-3 ratios on serum and structural lipids in rats

Abstract

Summary &horbar; The aim of this study was to compare the effects of dietary polyunsaturated fatty acids (PUFA) on serum and membrane lipids in rats fed diets containing moderate levels of fats (6% by weight). Control rats received enough PUFA to prevent any deficiency. Experimental rats were fed linseed oil, salmon oil, or sunflower oil. After 8 weeks of feeding, fasting serum triacylglycerol and cholesterol levels were not altered in the linseed oil group. In contrast, in the salmon oil group, serum cholesterol was lowered by 58% (P < 0.05) and the specific binding of heterologous LDL to liver plasma membrane was reduced by 31 % (P < 0.05). Unexpectedly, serum triacylglycerol levels were not significantly lowered (-14%) whereas they decreased (-32%; P < 0.05) in the sunflower oil group. Oleic acid, which has a stimulating effect on triacylglycerol synthesis and secretion, was less incorporated in serum and liver plasma membrane in rats fed sunflower oil than in rats fed other dietary lipids. This finding suggests that the effect of dietary sunflower oil was partly mediated by the reduction of oleic acid available for triacylglycerol synthesis. polyunsaturated fatty acid (n-6, n-3) / triacylglycerol / cholesterol / LDL receptor activity / liver plasma membrane Résumé &horbar; Effets de l'ingestion de quantités modérées de lipides différant par l'origine des acides gras de la série n-3 et par le rapport n-6/n-3 sur les lipides sériques et structuraux chez le rat. Ce travail a pour but de comparer les effets des acides gras polyinsaturés (AGPI) sur les lipides sériques et membranaires chez des rats ayant reçu des régimes contenant une quantité modérée de lipides (6% de l'aliment). Les rats témoins ont reçu les quantités dAGPI requises pour éviter la carence. Les rats expérimentaux ont reçu i) de l'huile de lin, ii) de l'huile de saumon, iii) de l'huile de tournesol. Après 8 sem de régime, les concentrations des triglycérides et du cholestérol du sérum à jeun n'ont pas été modifiées dans le groupe «huile de lin». En revanche, dans le groupe «huile de saumon» la concentration du cholestérol sérique a été réduite de 58% (P < 0,05) et la fixation spécifique de LDL hétérologues sur la membrane plasmique du foie a été réduite de 31 % (P < 0,05). De façon inattendue, les triglycérides du sérum n'ont diminué que de 14 % (non significatif) alors que, dans le groupe «huile de tournesol», une réduction de 32% (P < 0,05) a été observée. Dans le sérum et la membrane plasmique du foie, l'acide oléique, qui a la capacité d'augmenter la synthèse et la sécrétion des triglycérides, était incorporé en proportions plus faibles chez les rats «huile de tournesol&dquo; que chez les rats des autres groupes. Cette observation suggère que l'effet de l'huile de tournesol est en partie dû à la diminution de la quantité d'acide oléique disponible pour la synthèse des triglycérides.acide gras polyinsaturé (n-6, n-3) / triglycéride / cholestérol / activité récepteur LDL / membrane plasmique du foie

Effect of different dietary fats on the content of fatty acids in the the blood serum and in the <i>longissimus dorsi</i> muscle of rats

“…lipids in PUFA in response to the inclusion of linseed oil and, to a lesser extent, fish oil, was most likely a result of replacing MUFA by PUFA. Similarly as in this paper (Table 5), Fremont (1995) also observed a negative correlation between PUFA and MUFA. The synthesis of endogenous monounsaturated fatty acids classified as MUFA increases under a deficit of PUFA.…”

Effect of endurance training and/or fish oil supplemented diet on cytoplasmic fatty acid binding protein in rat skeletal muscles and heart

“…Similar to previous studies (Nelson et al 1997), we found that x-3 fatty acids had a lowering effect on plasma total-cholesterol and triglyceride concentrations. The cholesterol-HDL was also reduced, as reported by others in rodents (Fremont et al 1995). Because skeletal muscle is one of the most important organs involved in fatty acid metabolism in healthy humans it is very likely that it would be affected by the hypolipideamic properties of fish oil.…”

Influence of dietary lecithin and oils rich in n-3 polyunsaturated fatty acids (PUFA) on the fatty acid content of rat muscle and serum

“…Increased incorporation of n-3 polyunsatu-rated fatty acids (n-3 PUFA) into tissues using a diet containing n-3 fatty acids has been demonstrated in rats (Fremont et al, 1995). The beneficial effect of n-3 PUFA is related to changes in the structure of membranes and to modulation of eicosanoid synthesis.…”