Enriched functional milk fat ameliorates glucose intolerance and triacylglycerol accumulation in skeletal muscle of rats fed high-fat diets.

PURPOSE: We examined the effect of a functional milk fat (FMF) on the glucose metabolism and its association with the intramuscular triacylglycerol (TAG) content in rats fed high-fat diets. METHODS: Male Wistar rats were fed for 60 days with S7 (soybean oil 7%), S30 (soybean oil 30%), MF30 (soybean oil 3% + milk fat 27%), or FMF30 (soybean oil 3% + FMF 27%) diets. An oral glucose tolerance test was performed. The levels of key metabolites in gastrocnemius muscle and mRNA levels of genes involved in glucose and lipid metabolism in muscle, epididymal white adipose tissue (EWAT), and serum were assessed. RESULTS: The S30 diet induced glucose intolerance and led to TAG, citrate, and glucose accumulation in muscle. Moreover, we observed a downregulation of uncoupling proteins (Ucp2 and Ucp3) and insulin receptor substrate-1 (Irs1) genes, lower carnitine palmitoyl transferase-1b (CPT-1b), and phosphofructokinase-1 (PFK1) activities in muscle and lower expression of adiponectin (Adipoq) in EWAT. The FMF30 diet ameliorated the glucose intolerance and normalized the glucose and TAG levels in muscle, preventing the accumulation of citrate and enhancing glucose utilization by the PFK1. The beneficial effects might also be related to the higher expression of Adipoq in EWAT, its receptor in muscle (Adipor1), and the expression of Ucp2, Ucp3, and Irs1 in muscle, restoring the alterations observed with the S30 diet. CONCLUSIONS: FMF30 modulated key genes involved in glucose and lipid metabolism in skeletal muscle, improving the glucose utilization and preventing TAG, glucose, and citrate accumulation.

Maternal conjugated linoleic acid consumption prevented TAG alterations induced by a high-fat diet in male adult rat offspring.

Maternal nutritional programming by a high-fat (HF) diet is related to hepatic lipid accumulation and steatosis in offspring. Conjugated linoleic acid (CLA) might ameliorate impaired hepatic lipid homoeostasis; therefore, the aim was to investigate the potential preventive effect of maternal CLA consumption on TAG metabolism alterations induced by HF diets in adult male rat offspring receiving or not receiving CLA. Female Wistar rats were fed a control (C) diet, HF diet or HF diet supplemented with CLA (HF+CLA) for 4 weeks before mating and throughout pregnancy and lactation. After weaning, for 9 weeks, male offspring of C or HF rats continued with the same diets as their mothers (C/C or HF/HF groups, respectively) and male offspring of HF+CLA rats were fed HF or HF+CLA diets (HF+CLA/HF or HF+CLA/HF+CLA groups, respectively). Nutritional parameters, serum and liver TAG levels, the TAG secretion rate (TAG-SR) and the activities as well as gene expression of key hepatic enzymes involved in TAG regulation were assessed. The most interesting results were that maternal CLA decreased epididymal white adipose tissue weight and prevented serum and liver TAG accumulation induced by a HF diet in adult male offspring receiving or not receiving CLA. The prevention of liver steatosis in HF+CLA/HF+CLA and HF+CLA/HF offspring was associated with an increased hepatic TAG-SR. Overall, this study provides evidence that maternal CLA consumption programmes TAG regulation and in this way contributes to lowering lipid levels in tissues and preventing liver steatosis in particular.

Dietary fatty acids and the time elapsed from their intake are related to their composition in rat submandibular gland and salivary flow rates.

OBJECTIVES: The aim of this study was to analyze the influence of dietary fatty acids (FAs) and the time elapsed from their intake on FA tissue profile of rat submandibular gland (SG) and on its salivary flow rate (SFR). Do dietary FAs depending on the intake time modify their profile in SG and consequently the SFR? MATERIALS AND METHODS: Thirty-six adult male Wistar rats were fed on control diet (corn oil, CD, 18:2 n-6 FA) for 7 days and then divided into CD and two groups with replacement of corn oil by olive (OD, 18:1 n-9 FA) or chia (ChD, 18:3 n-3 FA) oils (1 and 30 day intake). Submandibular ducts were canalized to collect saliva for 20 min (µL/min). SG were examined (optical/electron microscopy; ImageJ 1.48 software). RESULTS: SFR values were 6.18 ± 0.34 (CD1), 6.04 ± 0.31 (OD1), and 6.00 ± 0.50 (ChD1) (p > 0.05). At 30-day intake, higher SFR values in ChD (7.82 ± 0.7) with respect to CD (4.68 ± 0.44; p < 0.001) and OD (6.08 ± 0.2; p = 0.038) were found. ChD30 showed a higher serous acinous area percentage than CD30 and OD30, whereas mucous acinous density was greater in CD30 than in OD30 and ChD30 (p < 0.05). α-Linolenic (ALA) and eicosapentaenoic and docosahexaenoic acid levels were only detected in SG of ChD30, while arachidonic acid was lower in this group as compared with CD30 and OD30 (p < 0.05). CONCLUSIONS: SG FA composition and its SFR appear to be modulated by dietary FAs and the time elapsed from their consumption. SFR is highest with n-3 ALA-rich ChD at 30-day intake. CLINICAL RELEVANCE: Diet could contribute to improve secretory dysfunctions.

Influence of trans fatty acids on glucose metabolism in soleus muscle of rats fed diets enriched in or deprived of linoleic acid.

PURPOSE: Industrial trans fatty acid (TFA) intake leads to impaired glucose metabolism. However, the overall effects reported are inconsistent and vary with the dietary FA composition and TFA isomer type and levels. We investigated TFA effects on glucose uptake, incorporation and oxidation, and glycogen synthesis in incubated soleus muscle under basal conditions or after treatment with insulin and/or palmitate. METHODS: Male Wistar rats were fed either linoleic acid (LA)-enriched (+LA) or LA-deprived (-LA) diet, supplemented (+LA + TFA or -LA + TFA) or not with TFA, for 60 days. Soleus muscle glucose metabolism was assessed in the absence or presence of insulin and/or palmitic acid. RESULTS: Under basal conditions, TFA enhanced glucose uptake and oxidation regardless of the LA status. Both TFA-supplemented groups had lower insulin response to glucose metabolism. Under insulin-stimulated conditions, TFA prevented the palmitate inhibition of muscle glucose uptake and metabolism in the +LA + TFA group. CONCLUSION: Dietary TFA enhanced glucose utilization in incubated soleus muscle under basal conditions and prevented the palmitate-induced inhibition in insulin-stimulated conditions. However, TFA reduced the insulin response to glucose uptake and metabolism. The effects mentioned above were influenced by the FA profile modifications induced by the dietary LA levels, suggesting that lipid metabolization and incorporation into plasma membrane are important determining factors of glucose metabolism and insulin sensitivity.

Maternal conjugated linoleic acid modulates TAG metabolism in adult rat offspring.

Conjugated linoleic acid (CLA) might regulate the lipid depots in liver and adipose tissue. As there is an association between maternal nutrition, fat depots and risk of offspring chronic disease, the aim was to investigate the effect of maternal CLA consumption on TAG regulation and some inflammatory parameters in adult male rat offspring receiving or not receiving CLA. Female Wistar rats were fed control (C) or CLA-supplemented (1 %, w/w) diets during 4 weeks before and throughout pregnancy and lactation. After weaning, male offspring of CLA rats were fed C or CLA diets (CLA/C and CLA/CLA groups, respectively), whereas C male rat offspring were fed a C diet (C/C group) for 9 weeks. Serum TAG levels were increased in the CLA/CLA and CLA/C groups, associated with a reduction of lipoprotein lipase activity and weights of adipose tissue. The liver TAG levels were decreased in the CLA/CLA group, related to a significant reduction of fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC) and glucose-6-phosphate dehydrogenase enzyme activities, as well as to the mRNA levels of FAS, ACC, stearoyl-CoA desaturase-1 and sterol regulatory element-binding protein-1c. Even though normal TAG levels were found in the liver of CLA/C rats, a reduction of lipogenesis was also observed. Thus, these results demonstrated a programming effect of CLA on the lipid metabolic pathways leading to a preventive effect on the TAG accretion in adipose tissue and the liver of male rat offspring. This knowledge could be important to develop some dietary strategies leading to a reduced incidence of obesity and fatty acid liver disease in humans.

N-3 fatty acids reduced trans fatty acids retention and increased docosahexaenoic acid levels in the brain.

INTRODUCTION: The levels of docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) are critical for the normal structure and function of the brain. Trans fatty acids (TFA) and the source of the dietary fatty acids (FA) interfere with long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis. OBJECTIVES: The aim of this study was to investigate the effect of TFA supplementation in diets containing different proportions of n-9, n-6, and n-3 FA on the brain FA profile, including the retention of TFA, LC-PUFA levels, and n-6/n-3 PUFA ratios. These parameters were also investigated in the liver, considering that LC-PUFA are mainly bioconverted from their dietary precursors in this tissue and transported by serum to the brain. Also, stearoyl-CoA desaturase-1 (SCD1) and sterol regulatory element-binding protein-1c (SREBP-1c) gene expressions were evaluated. METHODS: Male CF1 mice were fed (16 weeks) diets containing different oils (olive, corn, and rapeseed) with distinct proportions of n-9, n-6, and n-3 FA (55.2/17.2/0.7, 32.0/51.3/0.9, and 61.1/18.4/8.6), respectively, substituted or not with 0.75% of TFA. FA composition of the brain, liver, and serum was assessed by gas chromatography. RESULTS: TFA were incorporated into, and therefore retained in the brain, liver, and serum. However, the magnitude of retention was dependent on the tissue and type of isomer. In the brain, total TFA retention was lower than 1% in all diets. DISCUSSION: Dietary n-3 PUFA decreased TFA retention and increased DHA accretion in the brain. The results underscore the importance of the type of dietary FA on the retention of TFA in the brain and also on the changes of the FA profile.

Progress towards elimination of trans-fatty acids in foods commonly consumed in four Latin American cities.

OBJECTIVE: To assess progress towards the elimination of trans-fatty acids (TFA) in foods after the 2008 Pan American Health Organization (PAHO) recommendation of virtual elimination of TFA in Latin America. DESIGN: A descriptive, comparative analysis of foods that were likely to contain TFA and were commonly consumed in four cities in Latin America. SETTING: San José (Costa Rica), Mexico City (Mexico), Rio de Janeiro (Brazil), Buenos Aires (Argentina). SUBJECTS: Foods from each city were sampled in 2011; TFA content was analysed using GC. TFA of selected foods was also monitored in 2016. RESULTS: In 2011-2016, there was a significant decrease in the content of TFA in the sampled foods across all sites, particularly in Buenos Aires (from 12·6-34·8 % range in 2011-2012 to nearly 0 % in 2015-2016). All sample products met the recommended levels of TFA content set by the PAHO. TFA were replaced with a mixture of saturated and unsaturated fats. CONCLUSIONS: Our results indicate a virtual elimination of TFA from major food sources in the cities studied. This could be due to a combination of factors, including recommendations by national and global public health authorities, voluntary and/or mandatory food reformulation made by the food industry.

Saturated and trans fatty acids content in unpackaged traditional bakery products in Santa Fe city, Argentina: nutrition labeling relevance.

Studies have reported the relationship between the excessive intake of saturated fatty acids (SFA) and trans fatty acids (t-FA) and an increased risk of cardiovascular disease. Since 2006, the MERCOSUR countries require that the mandatory nutrition labeling should include information not only about the content of SFA but also about the content of t-FA. This does not apply to fractionated products at the point of retail, such as bakery products. This paper aimed to determine the total fat content and the fatty acid profile in unpackaged traditional bakery products (breads, biscuits and pastries) in Santa Fe, Argentina. Except for French bread, the contribution of t-FA and SFA to the total FA consumption from baked products was high. On the other hand, due to the high variability detected in the FA composition of bakery products between bakeries, it would be necessary to implement regulations making nutrition labeling mandatory in these products.

The effects of trans-fatty acids on TAG regulation in mice depend on dietary unsaturated fatty acids.

The aim of this study was to investigate the effects of trans-fatty acids (TFA) on liver and serum TAG regulation in mice fed diets containing different proportions of n-3, n-6 and n-9 unsaturated fatty acids (UFA) from olive (O), maize (C) or rapeseed (R) oils partially substituted or not with TFA (Ot, Ct and Rt, respectively). Male CF1 mice were fed (30 d) one of these diets. The effects of the partial substitution (1 %, w/w) of different UFA with TFA on the activity and expression of hepatic enzymes involved in lipogenesis and fatty acids oxidation were evaluated, as well as their transcription factor expressions. Some of the mechanisms involved in the serum TAG regulation, hepatic VLDL rich in TAG (VLDL-TAG) secretion rate and lipoprotein lipase (LPL) activity were assessed. In liver, TFA induced an increase in TAG content in the Ot and Rt groups, and this effect was associated with an imbalance between lipogenesis and ß-oxidation. In the Ot group, exacerbated lipogenesis may be one of the mechanisms responsible for the liver steatosis induced by TFA, whereas in Rt it has been related to a decreased ß-oxidation, compared with their respective controls. The enhanced hepatic VLDL-TAG secretion in the Ot and Rt groups was compensated with a differential removal of TAG by LPL enzyme in extrahepatic tissues, leading to unchanged serum TAG levels. In brief, the effects of low levels of TFA on liver and serum TAG regulation in mice depend on the dietary proportions of n-3, n-6 and n-9 UFA.

Nutriomic effects of precision lipids on murine hepatic triacylglycerol alterations induced by high-fat diets.

INTRODUCTION: This study aims to investigate if a mixture of functional lipids (FL), containing conjugated linoleic acid (CLA), tocopherols (TP) and phytosterols (PS) prevents some lipid alterations induced by high-fat (HF) diets, without adverse effects. METHODS: Male CF1 mice (n=6/group) were fed (4 weeks) with: control (C), HF or HF+FL diets. RESULTS: FL prevented the overweight induced by the HF diet, and reduced the adipose tissues (AT) weight, associated with lower energy efficiency. After the intervention period, the serum triacylglycerol (TAG) levels, in both HF diets underwent a decrease associated with an enhanced LPL activity (mainly in muscle). The beneficial effect of the FL mixture on body weight gain and AT weight, might be attributed to the decreased lipogenesis, denoted by the lower mRNA levels of SREBP1-c and ACC in AT, as well as, by an exacerbated lipid catabolism, reflected by increased mRNA levels of PPARα, ATGL, HSL and UCP2 in adipose tissue. Liver TAG levels were reduced in the HF+FL group due to an elevated lipid oxidation associated with a higher CPT-1 activity and mRNA levels of PPARα and CPT-1a. Moreover, genes linked to fatty acid biosynthesis (SREBP1-c and ACC) showed decreased mRNA levels in both HF diets, this finding being more pronounced in the HF+FL group. CONCLUSION: The administration of a FL mixture (CLA+TP+PS) prevented some lipid alterations induced by a HF diet, avoiding frequent deleterious effects of CLA in mice through the modulation of gene expression related to the regulation of lipid metabolism.

Effects of trans-fatty acids on liver lipid metabolism in mice fed on diets showing different fatty acid composition.

AIM: Our aim was to investigate the effects of trans-fatty acids (TFA) on liver lipid metabolism in mice fed on experimental diets rich in either oleic or linoleic acid. METHODS: Twenty-two male CF1 mice (22.0 ± 0.1 g) were fed with diets rich in corn oil or olive oil, supplemented or not with TFA (0.75 g TFA/100 g diet), for 4 weeks. Changes in triacylglycerol content, the activity and expression of enzymes involved in lipogenesis and fatty acid oxidation were measured. RESULTS: Supplementation of an olive oil-rich diet with TFA increased liver triacylglycerols, the activity and expression of lipogenic enzymes and sterol regulatory element-binding protein SREBP-1a expression. By contrast, when TFA were added to a corn oil-rich diet, they did not modify these parameters. No significant differences were observed among the experimental groups in the activity and expression of carnitine palmitoyltransferase-Ia, body and liver weights or serum triacylglycerol concentrations. CONCLUSIONS: The effect of TFA on liver fat accumulation depends on the dietary fatty acid composition. Steatosis induced by TFA when included in an olive oil diet (but not in a corn oil diet) was associated with an increased lipogenesis but not with a decreased fatty acid oxidation in animals fed on the olive oil diet. This metabolic change is mediated by SREBP-1a but not by SREBP-1c, and seems to be independent of insulin.

Fatty acid metabolism in liver and muscle is strongly modulated by photoperiod in Fischer 344 rats.

Circadian and seasonal variations produce variations in physiological processes throughout the day and the year, respectively. In this sense, both the light and the moment of feeding are strong modulators of the central and peripheral clocks. However, little is known about its influence on certain metabolic parameters and on the composition of liver and muscle fatty acids (FA). In the present study, 24 Fischer 344 rats were exposed for 11 weeks to different photoperiods, L6, L12 and L18, with 6, 12 and 18 h of light/day, respectively. They were fed a standard diet. Serum metabolic parameters, gene expression of liver enzymes and gastrocnemius muscle involved in the synthesis, elongation, desaturation and ß-oxidation of FA were analyzed. We have found that exposure to different hours of light has a clear effect on FA composition and gene expression in the liver. Mainly, the biosynthesis of unsaturated FA was altered in the L18 animals with respect to those exposed to L12, while the L6 did not show significant changes. At the muscle level, differences were observed in the concentration of mono and polyunsaturated FA. A multivariate analysis confirmed the differences between L12 and L18 in a significant way. We conclude that exposure to long days produces changes in the composition of liver and muscle FA, as well as changes in the gene expression of oxidative enzymes compared to exposure to L12, which could be a consequence of different seasonal eating patterns.

Spatio-temporal patterns of the crustacean demersal fishery discard from the south Humboldt Current System, based on scientific observer program (2014-2019).

This study summarises six years of spatio-temporal patterns of the discarded demersal community fauna recorded by onboard scientific observer program for both artisanal and industrial crustacean fisheries between 2014 and 2019, from mesophotic to aphotic depths (96 to 650 m) along the southern Humboldt Current System (28-38°S). In this period, one cold and two warm climatic events were observed during the austral summer 2014, 2015-2016 (ENSO Godzilla), and 2016-2017 (coastal ENSO), respectively. Satellite information showed that Chlorophyll-a concentration varied seasonally and latitudinally, associated with upwelling centres, while equatorial wind stress decreased southward of 36°S. Discards were composed of 108 species, dominated by finfish and molluscs. The Chilean hake Merluccius gayi was dominant and ubiquitous (occurrence, 95% of 9104 hauls), being the most vulnerable species of the bycatch. Three assemblages were identified: assemblage 1 (~200 m deep), dominated by flounders Hippoglossina macrops and lemon crabs Platymera gaudichaudii, assemblage 2 (~260 m deep), dominated by squat lobsters Pleuroncodes monodon and Cervimunida johni and assemblage 3 (~320 m depth), dominated by grenadiers Coelorinchus aconcagua and cardinalfish Epigonus crassicaudus. These assemblages were segregated by depth, and varied by year, and geographic zone. The latter represented changes in the width of the continental shelf, increasing southward of 36°S. Alpha-diversity indexes (richness, Shannon, Simpson, and Pielou) also varied with depth and latitude, with higher diversity in deeper continental waters (>300 m), between 2018-2019. Finally, at a spatial scale of tens of kilometres, and a monthly basis, interannual variations of biodiversity occurred in the demersal community. Surface sea temperature, chlorophyll-a, or wind stress did not correlate with discarded demersal fauna diversity of the crustacean fishery operating along central Chile.

Functional milk fat enriched in conjugated linoleic acid prevented liver lipid accumulation induced by a high-fat diet in male rats.

The aim was to investigate the potential effect of functional milk fat (FMF), naturally enriched in conjugated linoleic acid, on the prevention of liver lipid accumulation and some biochemical mechanisms involved in the liver triacylglycerol (TAG) regulation in high-fat (HF) fed rats. Male Wistar rats were fed (60 days) with S7 (soybean oil, 7%) or HF diets: S30 (soybean oil, 30%), MF30 (soybean oil, 3% + milk fat -MF-, 27%) or FMF30 (soybean oil, 3% + FMF, 27%). Nutritional parameters, hepatic fatty acid (FA) composition, liver and serum TAG levels, hepatic TAG secretion rate (TAG-SR), lipoprotein lipase (LPL) activity in adipose tissue and muscle, activities and/or mRNA levels of lipogenic and ß-oxidative enzymes, and mRNA levels of transcription factors and FA transport proteins were assessed. The hepatic lipid accumulation induced by the S30 diet was associated with increased mRNA levels of FA transporters; and it was prevented by FMF through an increase in the hepatic TAG-SR, carnitine palmitoyltransferase-1a activity and peroxisome proliferator-activated receptor alpha mRNA levels, as well as by a reduction of the mRNA levels of FA transporters. The hypotriacylglyceridaemia observed in S30 was related with an increased LPL activity in adipose tissue and it was reverted by FMF through the increased hepatic TAG-SR. In brief, FMF prevented the liver lipid accumulation induced by HF diets by increasing the hepatic TAG-SR and ß-oxidation, and reducing the hepatic FA uptake. The increased hepatic TAG-SR induced by FMF could be responsible for the attenuation of serum TAG alterations.

Optimization of oil extraction from caiman fat. Characterization for use as food supplement.

The leather of Caiman latirostris is highly appreciated in the fashion industry and the meat is valued as an important food but its fat are usually discarded because it has no commercial value. However it is an alternative source of essential fatty acids and could be used for human consumption. The aim was to optimize the oil extraction from Caiman latirostris fat and to carry out the chemical and microbiological characterization for its use as food supplement. The oil obtained by fusion method contains fatty acids with high nutritional quality such as oleic acid (34%), linoleic acid (30%) and α-linolenic acid (2%). The atherogenicity index was 0.29 and the thrombogenicity index 0.47. The presence of mesophilic aerobic bacteria, coliform bacteria, Escherichia coli and Salmonella were not observed, and the oil is stable for 4 months at 25 °C and for at least 8 months in an inert atmosphere at 25 °C.

Effects of dietary conjugated linoleic acid at high-fat levels on triacylglycerol regulation in mice.

OBJECTIVE: Our aim was to investigate the effects of dietary conjugated linoleic acid (CLA) at high-fat (HF) levels on parameters related to triacylglycerol (TG) regulation and some potential impacts on liver damage. METHODS: Growing mice were fed a control diet (7% corn oil), an HF diet containing 20% corn oil, or an HF diet containing 3% CLA (HF + CLA) for 30 d. Tissue and organ weights, plasma and tissue TG levels, and parameters related to their regulation were evaluated. Liver oxidative status was also assessed. RESULTS: Dietary CLA showed detrimental and beneficial effects. CLA added to the HF diet caused hepatomegaly (+32%) and exacerbated the hepatic TG accumulation (+168%) observed with the HF diet without inducing liver damage; however, it significantly reduced plasma TG concentrations (-37%) and normalized muscular TG content. An increase in glutathione was associated with total normalization of liver lipid peroxidation. In addition, HF + CLA caused dystrophy of epididymal fat pads, even when the HF diet had increased the adipose tissue mass (30%). The biochemical mechanisms involved in the regulation of lipid levels were related to reduced (-20%) hepatic very low-density lipoprotein-TG secretion and decreased muscle (-35%) and adipose (-49%) tissue contributions to the removal of plasma TG by lipoprotein lipase enzymes. CONCLUSION: Examination of CLA at HF levels showed hepatomegaly and exacerbation of lipid accretion as a negative impact; however, some positive aspects such as hypotriglyceridemia and protection against oxidative stress were also induced. Even the fat reduction is nutritionally important for weight control; the biochemical mechanisms whereby CLA mediates the potential effects could produce undesirable metabolic alterations.

An Experimental and Numerical Analysis of the Compression of Bimetallic Cylinders.

This paper investigates the upsetting of bimetallic cylinders with an aluminum alloy center and a brass ring. The influence of the center-ring shape factor and type of assembly fit (interference and clearance), and the effect of friction on the compression force and ductile damage are comprehensively analyzed by means of a combined numerical-experimental approach. Results showed that the higher the shape factor, the lower the forces required, whereas the effect of friction is especially important for cylinders with the lowest shape factors. The type of assembly fit does not influence the compression force. The accumulated ductile damage in the compression of bimetallic cylinders is higher than in single-material cylinders, and the higher the shape factor, the lower the damage for the same amount of stroke. The highest values of damaged were found to occur at the middle plane, and typically in the ring. Results also showed that an interference fit was more favorable for preventing fracture of the ring than a clearance fit. Microstructural analysis by scanning electron microscopy revealed a good agreement with the finite element predicted distribution of ductile damage.

Effects of CLA at different dietary fat levels on the nutritional status of rats during protein repletion.

OBJECTIVE: Protein depletion is associated with decreased body weight gain, low nitrogen balance, intrahepatic lipid accumulation, and hypoalbuminemia. Because conjugated linoleic acid (CLA) can increase lean body mass, enhance feed efficiency, and modulate lipid metabolism, this study investigated the effects of CLA at two levels of dietary fat on energy efficiency, nitrogen retention, and plasmatic and hepatic lipid levels in rats during dietary protein repletion. METHODS: The animals were subjected to a moderate protein restriction for 14 d. After that, they were fed a protein repletion diet for 30 d, supplemented or not with CLA at recommended and high-fat levels. Energy efficiency, nitrogen balance, and nutritional parameters in serum and tissues were evaluated. RESULTS: Protein repletion improved most of the nutritional parameters evaluated independently of CLA supplementation at both fat levels. At recommended fat levels, CLA did not have any effect. At high-fat levels, energy efficiency increased more than 20% by fat accumulation in carcasses and epididymal pads, serum cholesterol increased (two-fold), and liver triacylglycerol accumulation remained elevated. However, at high-fat levels, CLA prevented lipid accumulation in liver and adipose tissue. CONCLUSION: Protein repletion improved the nutritional status of protein-restricted rats with minor effects of CLA at both dietary fat levels. However, when high-fat diets were given, CLA-enriched oil showed preventive effects on liver and adipose tissue lipid accumulation and no deleterious effects were observed. Because there are no studies dealing with CLA effects on protein repletion, this experimental model could improve nutritional interventions to overcome the protein-deficit stage.

Study of iron homeostasis following partial hepatectomy in rats with chronic aluminum intoxication.

Effects of both chronic aluminum (Al) exposure and partial hepatectomy on iron (Fe) homeostasis were studied. Male Wistar rats were intraperitoneally administered either 27 mg Al/kg body weight (as aluminum hydroxide) or the vehicle saline, three times a week for 3 mo. After this time, half of the rats of each group was sham operated (SH) and the other half was partially hepatectomized (PH). Animals of the four experimental groups (vehicle+SH [SH]; Al+SH; vehicle+PH [PH], and Al+PH) were killed 48 h after the surgical procedure. Serum, hepatic, and intestinal Al levels were found to be increased both for Al+SH and Al+PH. The serum Fe concentration and transferrin saturation percentage were significantly diminished in the rats of the Al+PH group, thus showing interaction between Al administration and PH. The 59Fe mucosal-to-serosal transport, studied in the intestinal loop in situ, was not affected by Al or PH. The malregulation of intestinal Fe absorption in Al exposure and/or PH when the serum Fe concentration was diminished could be the result of the increased lipid peroxidation (thiobarbituric acid-reactive substances [TBARS]) observed in this tissue. Mucosal TBARS were increased by Al exposure (+26%) and PH (+37%) and interaction between Al and PH was observed (+44%). These results show that when liver surgery is performed after prolonged Al exposure, it leads to impairment of Fe homeostasis. We underline the importance of the exposure to Al, a potentially toxic element, in the study of risk assessment in patients who must be submitted to major liver resection.

Involvement of oxidative stress in the impairment in biliary secretory function induced by intraperitoneal administration of aluminum to rats.

We have shown that aluminum (Al) induces cholestasis associated with multiple alterations in hepatocellular transporters involved in bile secretory function, like Mrp2. This work aims to investigate whether these harmful effects are mediated by the oxidative stress caused by the metal. For this purpose, the capability of the antioxidant agent, vitamin E, to counteract these alterations was studied in male Wistar rats. Aluminum hydroxide (or saline in controls) was administered ip (27 mg/kg body weight, three times a week, for 90 d). Vitamin E (600 mg/kg body weight) was coadministered, sc. Al increased lipid peroxidation (+50%) and decreased hepatic glutation levels (-43%) and the activity of glutation peroxidase (-50%) and catalase (-88%). Vitamin E counteracted these effects total or partially. Both plasma and hepatic Al levels reached at the end of the treatment were significantly reduced by vitamin E (-40% and -44%, respectively; p<0.05). Al increased 4 times the hepatic apoptotic index, and this effect was fully counteracted by vitamin E. Bile flow was decreased in Altreated rats (-37%) and restored to normality by vitamin E. The antioxidant normalized the hepatic handling of the Mrp2 substrates, rose bengal, and dinitrophenyl-S-glutathione, which was causally associated with restoration of Mrp2 expression. Our data indicate that oxidative stress has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage, and the impairment in liver transport function induced by Al and that vitamin E counteracts these harmful effects not only by preventing free-radical formation but also by favoring Al disposal.