Diet supplementation with the cis-9,trans-11 conjugated linoleic acid isomer affects the size of adipocytes in Wistar rats

Previous reports have demonstrated that conjugated linoleic acid (CLA) acts on body fat accumulation in a variety of animal models. The aim of the present study was to investigate the effect of cis (c)-9,trans (t)-11 and t10,c12 CLA isomers on the number and size of adipocytes from the inguinal and retroperitoneal fats in Wistar male rats. A 5.1% palm oil–based diet was supplemented with CLA isomers as follows: 0.6% of c9,t11, 0.6% of t10,c12, 1.3% of c9,t11 and t10,c12 isomers in mixture, and a control nonsupplemented group for comparative purposes. Fat tissues were prepared on microscope slides for histologic examination using an image-analysis software to count the number of adipocytes and measure cell sizes. The results showed that CLA isomers did not affect (P > .05) either final body and fat depot weights or serum lipids (with the exception of triacylglycerols) and adipocytokines (leptin and adiponectin). Animals fed the c9,t11 CLA isomer diet showed larger adipocytes when compared to other groups. Independently of the CLA dietary treatment, retroperitoneal fat showed larger adipocytes (3319 μm²) and therefore a smaller number of adipocytes per unit of area, compared to inguinal fat (3055 μm²). Taken together, the data suggest that a palm oil–based diet supplemented with the c9,t11 CLA isomer in Wistar rats, in contrast to the t10,c12 isomer and the mixture of both isomers, increases adipocyte dimensions in inguinal and retroperitoneal fat depots, while having a minor effect in serum lipids and adipocytokines.     

Dietary conjugated linoleic acid isomers change the unsaturation degree of hepatic fatty acids in neutral lipids but not in polar lipids

The fatty acid composition of phospholipids plays a key role in the structural and functional properties of cellular membrane. In this study, it was hypothesized that conjugated linoleic acid (CLA) isomer supplementation changes the unsaturation degree of the fatty acids of neutral lipids (NLs) but not those of polar lipids (PLs). Thus, the main goal was to determine the pattern of fatty acid incorporation into hepatic PL and NL fractions. Wistar male rats were fed cis(c)9,trans(t)11 and t10,c12 CLA isomers, separately or as a mixture. Whereas the t10,c12 isomer incorporation in the PL fraction was similar when supplemented either individually or as a mixture, the c9,t11 isomer reached the highest values of incorporation when combined with t10,c12. In the PL fraction, the linoleic acid did not change; but the arachidonic acid decreased, especially in the rats given the mixture. Also in this fraction, the t10,c12 isomer, either separately or as a mixture, decreased the amounts of n-6 long-chain (LC) polyunsaturated fatty acids (PUFA) and increased those of the n-3 LC PUFA relative to the control. In the NL fraction, linoleic acid incorporation followed the diet composition, whereas the arachidonic acid was similar among treatments. Facing CLA isomer supplementation, the present study suggests that fatty acid incorporation into phospholipids, through the balance between n-6 and n-3 LC PUFA, is dependent upon maintaining the unsaturation degree of cellular membrane.     

trans-11 18:1 Vaccenic Acid (TVA) Has a Direct Anti-Carcinogenic Effect on MCF-7 Human Mammary Adenocarcinoma Cells

Trans vaccenic acid (TVA; trans-11 18:1) is a positional and geometric isomer of oleic acid and it is the predominant trans isomer found in ruminant fats. TVA can be converted into cis-9, trans-11 conjugated linoleic acid (c9, t11-CLA), a CLA isomer that has many beneficial effects, by stearoyl CoA desaturase 1 (SCD1) in the mammary gland. The health benefits associated with CLA are well documented, but it is unclear whether trans fatty acids (TFAs) from ruminant products have healthy effects. Therefore, the effects of TVA on the proliferation of MCF-7 human breast adenocarcinoma cells and MCF-10A human breast epithelial cells were investigated in the present study. Results showed that TVA inhibited the proliferation of MCF-7 cells but not MCF-10A cells by down-regulating the expression of Bcl-2 as well as procaspase-9. In addition, the suppressive effect of TVA was confirmed in SCD1-depleted MCF-7 cells. Our results suggested that TVA exerts a direct anti-carcinogenic effect on MCF-7 cells. These findings provided a better understanding of the research on the anti-carcinogenic effects of TVA and this may facilitate the manufacture of TVA/c9, t11-CLA fortified ruminant products.     

Conjugated linoleic acid is related to bone mineral density but does not affect parathyroid hormone in men

The relationships between conjugated linoleic acid (CLA) status, bone, body composition, and the effect of CLA on calciotropic hormones are unclear. A cross-sectional study was designed to examine the association between c9, t11 CLA status in erythrocyte membranes (RBC) and body composition. This preceded a dose-response trial investigating if c9, t11 CLA affected parathyroid hormone (PTH). It was hypothesized that (1) higher c9, t11 CLA status in RBC will be associated with a lower fat and higher bone mass and that (2) PTH will be reduced by 30% after supplementation of c9, t11 CLA. Fifty-four men (age, 19-53 years) were included in the cross-sectional analysis, of which 31 were studied in the dose-response trial and randomized to 1 of 3 groups: placebo (n = 10), 1.5 g/d (n = 11), or 3.0 g/d (n = 10) of c9, t11 CLA for 16 weeks. Men with RBC c9, t11 CLA status above the median had higher whole body bone mineral density (BMD) (1.359 ± 0.024 vs 1.287 ± 0.023 g/cm²; P = .04) and whole body lean mass (WBL) percentage (78.8% ± 0.9% vs 75.3% ± 1.0%; P = .01), whereas body mass index (24.8 ± 0.5 kg/m² vs 27.3 ± 0.9 kg/m²; P = .01) and whole body fat mass percentage (17.3% ± 0.9% vs 21.3% ± 1.1%; P = .007) were lower. In regression analysis, RBC c9, t11 CLA status accounted for a significant proportion (r² = 0.10) of the variation in whole body BMD (P = .03). There were no time or treatment differences among any bone or biomarkers of bone metabolism including PTH. These findings indicate that RBC c9, t11 CLA status, a reflection of long-term (~4 months) dietary CLA intake, positively relates to BMD. However, c9, t11 CLA supplementation does not appear to affect PTH in healthy men.     

Quantitative determination of conjugated linoleic acid isomers by silver ion HPLC in ewe milk fat

The aim of this research was to validate a method for the quantification of conjugated linoleic acid (CLA) isomers in the fat of ewe's milk. The isomers in the form of methyl ester (FAME) are separated by silver ion high performance liquid chromatography (Ag⁺HPLC) and the quantification was based on the measurement of the integrated area under the 231 nm peaks, using external CLA reference standards. The response linearity is maintained in a wide range of concentrations and the quantification limit estimated was of 0.005 μg/injection for the cis-9,trans-11 and trans-10,cis-12 isomers. Referred to the samples this limit would be 0.008 mg/g of fat in the usual working conditions. In the precision assay an RSDr of 2.14% for the isomer cis-9,trans-11 was calculated and for the rest of the CLA isomers varied between 2.08 and 7.5%. The recovery assays were performed adding CLA cis-9,trans-11 triglyceride and the mean recovery was 96%. The method proposed allows the determination of the individual content of different CLA isomers using one single technique, HPLC and supposes saving time and resources.     

Dietary supplementation with conjugated linoleic acid plus n-3 polyunsaturated fatty acid increases food intake and brown adipose tissue in rats

The effect of supplementation with 1% conjugated linoleic acid and 1% n-3 long chain polyunsaturated fatty acids (CLA/n-3) was assessed in rats. Food intake increased with no difference in body weights. White adipose tissue weights were reduced whereas brown adipose tissue and uncoupling protein-1 expression were increased. Plasma adiponectin, triglyceride and cholesterol levels were reduced while leptin, ghrelin and liver weight and lipid content were unchanged. Hypothalamic gene expression measurements revealed increased expression of orexigenic and decreased expression of anorexigenic signals. Thus, CLA/n-3 increases food intake without affecting body weight potentially through increasing BAT size and up-regulating UCP-1 in rats.     

Total dietary fat and fatty acid content modifies plasma phospholipid fatty acids,desaturase activity indices,and urinary prostaglandin E in women

Compared with diets high in fat, low-fat diets are associated with reduced risk of cardiovascular disease. We hypothesized that a low-fat (LF) (20% fat) and an LF high–omega-3 (n-3) fatty acid diet (LFn3) (23% fat with 3% as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid [DHA]) would enhance n-3 composition of plasma phospholipid fatty acid and reduce urinary prostaglandin E₂ (PGE₂) relative to a high-fat diet (HF) (40% fat) and that these changes would be associated with alterations in δ5 desaturase (D5D) and δ6 desaturase (D6D) activity. Phospholipid fatty acids and urinary PGE₂ were measured, and D5D and D6D activity indices calculated in a crossover trial in 17 postmenopausal women fed each of 3 test diets (HF, LF, and LFn3) for 8-week feeding periods. Desaturase activity indices were calculated as D5D, 20:4n-6/20:3n-6, and D6D, 20:3n-6/18:2n-6. Plasma phospholipid fatty acid, α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid (DPA), DHA, and total n-3 fatty acids increased, whereas linoleic acid and arachidonic acid decreased with consumption of LFn3. The LF resulted in enhanced arachidonic acid and DHA. High fat reduced D6D, whereas both HF and LF increased D5D. Urinary PGE₂ was reduced in response to both the LF and LFn3 diets. Low-fat diets, with or without long-chain n-3 fatty acids, promote positive health effects due in part to favorable alteration of plasma phospholipid fatty acid profiles and modification in desaturase activity indices, suggesting that the type and amount of fat consumed are modifiable risk factors for the prevention of cardiovascular disease.     

Omega-3 fatty acid deficiency selectively up-regulates delta6-desaturase expression and activity indices in rat liver: prevention by normalization of omega-3 fatty acid status

This study investigated the effects of perinatal dietary omega-3 (n-3) fatty acid depletion and subsequent repletion on the expression of genes that regulate long-chain (LC) polyunsaturated fatty acid biosynthesis in rat liver and brain. It was hypothesized that chronic n-3 fatty acid deficiency would increase liver Fads1 and Fads2 messenger RNA (mRNA) expression/activity and that n-3 fatty acid repletion would normalize this response. Adult rats fed the n-3-free diet during perinatal development exhibited significantly lower erythrocyte, liver, and frontal cortex LCn-3 fatty acid composition and reciprocal elevations in LC omega-6 (n-6) fatty acid composition compared with controls (CONs) and repleted rats. Liver Fads2, but not Fads1, Elovl2, or Elovl5, mRNA expression was significantly greater in n-3-deficient (DEF) rats compared with CONs and was partially normalized in repleted rats. The liver 18:3n-6/18:2n-6 ratio, an index of delta6-desturase activity, was significantly greater in DEF rats compared with CON and repleted rats and was positively correlated with Fads2 mRNA expression among all rats. The liver 18:3n-6/18:2n-6 ratio, but not Fads2 mRNA expression, was also positively correlated with erythrocyte and frontal cortex LCn-6 fatty acid compositions. Neither Fads1 or Fads2 mRNA expression was altered in brain cortex of DEF rats. These results confirm previous findings that liver, but not brain, delta6-desaturase expression and activity indices are negatively regulated by dietary n-3 fatty acids.     

Capsaicin attenuates palmitate-induced expression of macrophage inflammatory protein 1 and interleukin 8 by increasing palmitate oxidation and reducing c-Jun activation in THP-1 (human acute monocytic leukemia cell) cells

Capsaicin, a spicy component of hot peppers, has been shown to improve inflammatory disease and obesity. In this study, we tested the hypothesis that the anti-inflammatory activity of capsaicin can be used to improve free fatty acid (FFA)-induced inflammation by reducing gene expression of macrophage inflammatory protein 1 (MIP-1) and interleukin 8 (IL-8) in THP-1 (human acute monocytic leukemia cell) macrophages. To investigate whether capsaicin ameliorates palmitate-induced MIP-1 and IL-8 gene expressions, we treated THP-1 cells with palmitate in the presence or absence of capsaicin and measured MIP-1 and IL-8 by real-time polymerase chain reaction. To elucidate the mechanism by which capsaicin effects on palmitate-induced MIP-1 and IL-8 gene expressions, we performed immunoblotting with stress kinase-related antibodies and measured palmitate oxidation and palmitate oxidation-related gene expression. Palmitate and stearate but not the unsaturated FFA oleate significantly increased MIP-1 and IL-8 expressions in THP-1 macrophages. Treatment with capsaicin or FFA oxidation stimulators inhibited palmitate-induced MIP-1 and IL-8 expressions in THP-1 macrophages. Capsaicin increased the gene expression of carnitine palmitoyltransferase 1 and the β-oxidation of palmitate. Furthermore, capsaicin significantly reduced palmitate-stimulated activation of c-Jun N-terminal kinase, c-Jun, and p38. Our data suggest that the attenuation of palmitate-induced MIP-1 and IL-8 gene expressions by capsaicin is associated with reduced activation of c-Jun N-terminal kinase, c-Jun, and p38 and preserved β-oxidation activity.