Rat liver mitochondrial membrane characteristics and mitochondrial functions are more profoundly altered by dietary lipid quantity than by dietary lipid quality: effect of different nutritional lipid patterns

Abstract

Dietary lipids are known to affect the composition of the biological membrane and functions that are involved in cell death and survival. The mitochondrial respiratory chain enzymes are membrane protein complexes whose function depends on the composition and fluidity of the mitochondrial membrane lipid. The present study aimed at investigating the impact of different nutritional patterns of dietary lipids on liver mitochondrial functions. A total of forty-eight Wistar male rats were divided into six groups and fed for 12 weeks with a basal diet, lard diet or fish oil diet, containing either 50 or 300 g lipid/kg. The 30 % lipid intake increased liver NEFA, TAG and cholesterol levels, increased mitochondrial NEFA and TAG, and decreased phospholipid (PL) levels. SFA, PUFA and unsaturation index (UI) increased, whereas MUFA and trans-fatty acids (FA) decreased in the mitochondrial membrane PL in 30 % fat diet-fed rats compared with 5 % lipid diet-fed rats. PL UI increased with fish oil diet v. basal and lard-rich diets, and PL trans-FA increased with lard diet v. basal and fish oil diets. The 30 % lipid diet intake increased mitochondrial membrane potential, membrane fluidity, mitochondrial respiration and complex V activity, and decreased complex III and IV activities. With regard to lipid quality effects, b-oxidation decreased with the intake of basal or fish oil diets compared with that of the lard diet. The intake of a fish oil diet decreased complex III and IV activities compared with both the basal and lard diets. In conclusion, the characteristics and mitochondrial functions of the rat liver mitochondrial membrane are more profoundly altered by the quantity of dietary lipid than by its quality, which may have profound impacts on the pathogenesis and development of non-alcoholic fatty liver disease. Key words: High-fat diet: Lipid metabolism: Mitochondrial functions: Mitochondrial membrane: Respiratory complexes: RatsIncreasing consumption of fat-rich diets and reduced physical activity are the major contributors to the observed increase in body weight, diabetes and fatty liver diseases in many developed and developing countries, and have become a major public health concern (1 -4) . Lipids play varied and critical roles in cellular metabolism, with functions dramatically modulated by the individual fatty acid (FA) moieties in complex lipid entities. Moreover, biological membranes are composed of more than 50 % of lipids, and the quantity and quality of dietary lipids are known to have an impact on the composition, characteristics and functions of the biological membrane (5 -7) . FA as components of biological membranes strongly influence membrane fluidity, which, in turn, may influence many physiological processes involved in cell death and survival such as signal transduction, protein import, membrane receptor function and metabolite transport (8) . Moreover, the quality of administered lipid seems to play a crucial role in the occurrence (or not) of these alterations and their severity (9) . The...

Increased palmitate intake: higher acylcarnitine concentrations without impaired progression of β-oxidation

“…However, studies of the liver in pigs ( 11 ), rats ( 12 ), and mice ( 13,14 ) suggest that the PA and OA composition of neutral or "total" lipids, but not phospholipids, are directly affected by PA and OA intake ( 11 ). Moreover, in mice, it appears that a high OA intake cannot mitigate the OA-lowering effects of inhibition of stearoyl-CoA desaturase on the OA content of LDL.…”

“…Thus, we also sought to correlate serum ACs with the LPS-stimulated production of cytokines by peripheral blood mononuclear cells (PBMCs) isolated from the same subjects ( 15 ). an equal dose of PA tracer with each feeding, either [1][2][3][4][5][6][7][8][9][10][11][12][13] C]PA or C]PA in random order on two consecutive days. On day 20, at approximately 10:00 AM, the subject underwent an identical tracer study with the other PA isotope.…”

“…On day 21, the subjects underwent an identical feeding protocol, as on days 19 and 20, except [1][2][3][4][5][6][7][8][9][10][11][12][13] C]acetate was administered During the baseline/control diet phases, as well as during experimental diet phases (HPA or HOA), of the study, all solid food and liquids, except water, were given to the subject to ingest, and they were requested to entirely ingest each meal, which consisted of one-third of daily energy needs and which contained approximately the same proportion of macronutrients, including FAs, as a proportion of energy as the entire daily diet. Total daily energy intake was varied, if necessary, to maintain constant body weight.…”

“…However, while we acknowledge that the use of [1][2][3][4][5][6][7][8][9][10][11][12][13] C]4-methyl-2-oxovaleric (2-ketoisocaproic acid), from which acetyl-CoA is generated within the mitochondria, may be ideal for assessing isotope exchange in the TCA cycle, we were uncertain of the absorption of this compound. Third, skeletal muscle oxidation of PA was based on blood sampling ( 22 ) and not intramyocellular palmitoyl-CoA enrichment .…”

“…However, on either diet, we overestimated retention to the degree that food-derived PA was not completely absorbed . Similarly, skeletal muscle PA retention was equated to net uptake of PA across the forearm muscle minus skeletal muscle PA OX, with both skeletal muscle PA uptake and skeletal muscle PA retention calculated from data using the [1][2][3][4][5][6][7][8][9][10][11][12][13] C]PA tracer. Thus, we constructed a model of PA balance that is analogous to the term "leucine balance" ( 37 ).…”