Three dissimilar high fat diets differentially regulate lipid and glucose metabolism in obesity-resistant Slc:Wistar/ST rats

Fatty acids composition and in vivo biochemical effects of Aleurites moluccana seed (Candlenut) in obese wistar rats

BACKGROUND

Candlenut (CN) has been used indiscriminately for weight loss. In vivo effects of CN in different doses are scarce.

OBJECTIVE

To evaluate the effects of CN ingestion in obese rats.

DESIGN

Thirty animals (obese and non-obese) received one of three different types of treatments: placebo, CN ingestion in a popular therapeutic regimen (8 days with oral administration of 0.2 mg/kg followed by 20 days with doses of 0.4 mg/kg), and ingestion of a doubled popular dose-called 2CN. Treatment was maintained for 28 days.

RESULTS

The fatty acid profile of CN indicated mainly linolelaidic and palmitoleic acids. Rats receiving CN and 2CN showed reduced plasmatic levels of glucose and lipoproteins (p < 0.05). A dose-dependent carcass fat reduction was observed (p < 0.05). Blood levels of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) reduced with CN and increased with 2CN doses (p < 0.05). Alanine aminotransferase (ALT) and the atherogenic index remained similar among all treatments (p > 0.05). Hepatic vacuolation decreased with CN, but the 2CN dose produced mononuclear leucocyte infiltrate.

CONCLUSIONS

Although CN presented beneficial effects on the metabolism of rats, it also caused increased risk of liver damage.

Different Effects of Lard and Vegetable Blend Oil on Intestinal Microorganisms, Enzyme Activity and Blood Routine in Mice

The intake of moderate oils and fats is necessary to maintain the body's energy balance, and the fatty acid composition of different oils and fats varies in their nutrition and function. The study aimed to investigate the effects of lard and vegetable blend oil on gut microbiota, intestinal enzyme activities, and blood routine. Kunming mice were assigned to the three groups: (1) Control group (CK) was gavage administration with distilled water, (2) Plant oil group (ZWY) was gavage administration with edible vegetable blend oil, (3) Lard group (DWY) was gavage administration with lard. After 42 days, microbiological, digestive enzymes, and blood routine were performed. Compared with the CK group, Escherichia coli, Lactobacilli, and Bifidobacteria were significantly decreased (p < 0.05), the activities of protease, cellulase, amylase, and xylanase were markedly reduced (p < 0.05), the hemoglobin was significantly increased (p < 0.05) in the ZWY group and DWY groups, and the hematocrit was increased in the ZWY group (p < 0.05), while other routine blood indices were increased (p > 0.05). Compared to the ZWY group, the activity of cellulase and amylase were significantly increased (p < 0.05), the intestinal microorganism and the routine blood indexes had no significant difference in the DWY group. Lard and vegetable blend oil diet affected the composition of the intestinal microorganisms, and the functions of digestive enzymes. Meanwhile, the levels of digestive enzymes may be correlated with the intestinal microbiota.

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 β-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 β-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.

Excesive consumption of unsaturated fatty acids leads to oxidative and inflammatory instability in Wistar rats

Lifestyle modifications such as increase in high-fat food consumption importantly increases the risks for cardiovascular disease. The principal objective of this study is to analyze effects of different high fat diet (HFD) sources on haemodynamic parameters, lipid and oxidative profile, myeloperoxidase activity, and markers of inflammation (IL-6/pentraxin-3). HFD containing 20% of fat, provided by lard (saturated) or soybean oil (unsaturated), as well as control diet were administering to three groups (L, SO and C). Food efficiency ratio and plasma lipids were significantly elevated in both HFD groups. However, only SO group showed an increase in systolic arterial pressure, oxidative stress index, myeloperoxidase activity, liver lipids as well as markers of inflammation: IL-6 and pentraxin-3 (PTX3). In summary, these results indicate inflammogenic potential of excessive soybean oil consumption in triggering liver damage.

Fish oil and corn oil induced differential effect on beiging of visceral and subcutaneous white adipose tissue in high-fat-diet-induced obesity

Obesity is characterised by excessive accumulation of fat in white adipose tissue (WAT) which is compartmentalised into two anatomically and functionally diverse depots - visceral and subcutaneous. Advice to substitute essential polyunsaturated fatty acids (PUFAs) for saturated fatty acids is a cornerstone of various obesity management strategies. Despite an array of reports on the role of essential PUFAs on obesity, there still exists a lacuna on their mode of action in distinct depots i.e. visceral (VWAT) and subcutaneous (SWAT). The present study aimed to evaluate the effect of fish oil and corn oil on VWAT and SWAT in high-fat-diet-induced rodent model of obesity. Fish oil (FO) supplementation positively ameliorated the effects of HFD by regulating the anthropometrical and serum lipid parameters. FO led to an overall reduction in fat mass in both depots while specifically inducing beiging of adipocytes in SWAT as indicated by increased UCP1 and PGC1α. We also observed an upregulation of AMPKα and ACC1/2 phosphorylation on FO supplementation in SWAT suggesting a role of AMPK-PGC1α-UCP1 axis in beiging of adipose tissue. On the other hand, corn oil supplementation did not show any improvements in adipose tissue metabolism in both the depots of adipose tissue. The results were analysed using one-way ANOVA followed by Tukey's test in Graphpad Prism 5.0. Combined together our results suggest that n-3 PUFAs exert their anti-obesity effect by regulating adipokine secretion and inducing beiging of SWAT, hence increasing energy expenditure via thermogenic upregulation.

Fish oil diet effects on alveolar bone loss, in hypercholesterolemic rats

This study evaluated the effects of replacing a saturated fat diet by n-3 polyunsaturated fatty acids (n-3PUFA), on alveolar bone loss in hypercholesterolemic rats with experimental periodontitis (PD).

METHODS

Eight week old Wistar rats were assigned according to dietary intake. Control group (C, n = 15) fed a commercial diet throughout the experiment. Atherogenic group (AT, n = 30) fed AT diet for 3 weeks; thereafter, AT was randomized to receive either a n-3PUFA (n = 15) or to continue with AT (n = 15) diet. Subsequently, PD was induced in all groups by unilateral ligature (L) of the first molar (M1) of the left mandible, non-ligated contralateral molars served as controls. After every week of PD induction, 5 rats per group were euthanized. Serum was collected for lipids assays and hemi-mandibles were subjected to histomorphometric (% upper and lower interradicular bone volume and periodontal ligament height, hPDL) and radiographic analyses (periodontal bone support, PBS, in ligated teeth, between M1-M2).

RESULTS

Rats fed n-3PUFA diet rapidly induced a significant reduction in the serum lipids (p < 0.001). In all rats the ligated teeth showed a greater bone loss as compared with the unligated molars. At the end of the experiment the AT + L was the worst in % lower bone volume (p < 0.01), hPDL and PBS (p < 0.05). In contrast, rats fed n-3PUFA + L was similar to those rats fed C diet (p > 0.05).

CONCLUSION

Alveolar bone and dyslipidemia improved by substituting saturated fat intake for a n-3PUFA rich diet, in hypercholesterolemic rats with PD.

Benefits of Fish Oil Consumption over Other Sources of Lipids on Metabolic Parameters in Obese Rats

This study evaluated the effect of the consumption of different levels and sources of lipids on metabolic parameters of Wistar rats. Animals were fed with high-fat diet (HFD) containing 20% of lard for 12 weeks to cause metabolic obesity. Subsequently, the animals were divided into six groups and were fed diets with lipid concentrations of 5% or 20% of lard (LD), soybean oil (SO) or fish oil (FO), for 4 weeks. Data were submitted to analysis of variance (two-way) followed by Tukey post hoc test (p < 0.05). The groups that consumed FO showed less weight gain and lower serum levels of triacylglycerol (TAG), total cholesterol and fractions, aspartate aminotransferase (AST) activity, atherogenic index, less amount of fat in the carcass, decreased Lee index and lower total leukocyte counting (p < 0.05). These same parameters were higher in LD treatment (p < 0.05). In the concentration of 20%, carcass fat content, blood glucose levels, as well as alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) decreased in FO groups (p < 0.05). The SO group had intermediate results regarding the other two treatments (FO and LD). We concluded that fish oil intake was able to modulate positively the metabolic changes resulting from HFD.

Transcriptomic responses of the liver and adipose tissues to altered carbohydrate-fat ratio in diet: an isoenergetic study in young rats

Background

To elucidate the effects of altered dietary carbohydrate and fat balance on liver and adipose tissue transcriptomes, 3-week-old rats were fed three kinds of diets: low-, moderate-, and high-fat diets (L, M, and H) containing a different ratio of carbohydrate-fat (C-F) (65:15, 60:20, and 35:45 in energy percent, respectively).

Methods

The rats consumed the diets for 9 weeks and were subjected to biochemical and DNA microarray analyses.

Results

The rats in the H-group exhibited lower serum triacylglycerol (TG) levels but higher liver TG and cholesterol content than rats in the L-group. The analysis of differentially expressed genes (DEGs) between each group (L vs M, M vs H, and L vs H) in the liver revealed about 35% of L vs H DEGs that were regulated in the same way as M vs H DEGs, and most of the others were L- vs H-specific. Gene ontology analysis of these L vs H DEGs indicated that those related to fatty acid synthesis and circadian rhythm were enriched. Interestingly, about 30% of L vs M DEGs were regulated in a reverse way compared with L vs H and M vs H DEGs. These reversed liver DEGs included M-up/H-down genes (Sds for gluconeogenesis from amino acids) and M-down/H-up genes (Gpd2 for gluconeogenesis from glycerol, Agpat9 for TG synthesis, and Acot1 for beta-oxidation). We also analyzed L vs H DEGs in white (WAT) and brown (BAT) adipose tissues and found that both oxidation and synthesis of fatty acids were inhibited in these tissues.

Conclusions

These results indicate that the alteration of dietary C-F balance differentially affects the transcriptomes of metabolizing and energy-storing tissues.

Electronic supplementary material

The online version of this article (doi:10.1186/s12263-017-0558-2) contains supplementary material, which is available to authorized users.

Potential Role of Omega-3 Fatty Acids on the Myogenic Program of Satellite Cells

Skeletal muscle loss is associated with aging as well as pathological conditions. Satellite cells (SCs) play an important role in muscle regeneration. Omega-3 fatty acids are widely studied in a variety of muscle wasting diseases; however, little is known about their impact on skeletal muscle regeneration. The aim of this review is to evaluate studies examining the effect of omega-3 fatty acids, α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid on the regulation of SC proliferation and differentiation. This review highlights mechanisms by which omega-3 fatty acids may modulate the myogenic program of the stem cell population within skeletal muscles and identifies considerations for future studies. It is proposed that minimally three myogenic transcriptional regulatory factors, paired box 7 (Pax7), myogenic differentiation 1 protein, and myogenin, should be measured to confirm the stage of SCs within the myogenic program affected by omega-3 fatty acids.

Soybean Oil Is More Obesogenic and Diabetogenic than Coconut Oil and Fructose in Mouse: Potential Role for the Liver

The obesity epidemic in the U.S. has led to extensive research into potential contributing dietary factors, especially fat and fructose. Recently, increased consumption of soybean oil, which is rich in polyunsaturated fatty acids (PUFAs), has been proposed to play a causal role in the epidemic. Here, we designed a series of four isocaloric diets (HFD, SO-HFD, F-HFD, F-SO-HFD) to investigate the effects of saturated versus unsaturated fat, as well as fructose, on obesity and diabetes. C57/BL6 male mice fed a diet moderately high in fat from coconut oil and soybean oil (SO-HFD, 40% kcal total fat) showed statistically significant increases in weight gain, adiposity, diabetes, glucose intolerance and insulin resistance compared to mice on a diet consisting primarily of coconut oil (HFD). They also had fatty livers with hepatocyte ballooning and very large lipid droplets as well as shorter colonic crypt length. While the high fructose diet (F-HFD) did not cause as much obesity or diabetes as SO-HFD, it did cause rectal prolapse and a very fatty liver, but no balloon injury. The coconut oil diet (with or without fructose) increased spleen weight while fructose in the presence of soybean oil increased kidney weight. Metabolomics analysis of the liver showed an increased accumulation of PUFAs and their metabolites as well as γ-tocopherol, but a decrease in cholesterol in SO-HFD. Liver transcriptomics analysis revealed a global dysregulation of cytochrome P450 (Cyp) genes in SO-HFD versus HFD livers, most notably in the Cyp3a and Cyp2c families. Other genes involved in obesity (e.g., Cidec, Cd36), diabetes (Igfbp1), inflammation (Cd63), mitochondrial function (Pdk4) and cancer (H19) were also upregulated by the soybean oil diet. Taken together, our results indicate that in mice a diet high in soybean oil is more detrimental to metabolic health than a diet high in fructose or coconut oil.

Effects of a diet rich in n-3 polyunsaturated fatty acids on hepatic lipogenesis and beta-oxidation in mice

Here, we investigate whether a diet rich in fish oil can lead to the development of hepatic alterations associated with non-alcoholic fatty liver disease (NAFLD). To achieve this goal, we provided, for 8 weeks, four different diets to 3-month-old C57BL/6 mice: (a) standard-chow diet (SC; 40 g soybean oil/kg diet, 10 % of the total energy content from lipids), (b) fish oil diet (FO; 4 g soybean oil and 36 g fish oil/kg diet, 10 % of the total energy content from lipids), (c) high-fat diet (HF; 40 g soybean oil and 238 g lard/kg diet, 50 % of the total energy content from lipids), and (d) high-fish oil diet (HFO; 40 g soybean oil and 238 g fish oil/kg diet, 50 % of the total energy content from lipids). Biochemical analyses, stereology, western-blotting and RT-qPCR were used. In the HF group, we found evidence of obesity, metabolic syndrome, and liver damage, along with hypertriglyceridemia, hepatic insulin resistance, and steatosis. On the other hand, the HFO group did not present these alterations and remained similar to the controls. The changes observed in the animals fed the HF diet were accompanied by an increase in hepatic lipogenesis and a decrease in beta-oxidation; meanwhile, in the HFO group, the opposite results were found, that is, reduced lipogenesis and elevated beta-oxidation, were most likely responsible for the prevention of deleterious hepatic alterations and liver damage. In conclusion, a diet rich in fish oil has beneficial effects on hepatic insulin resistance, lipogenesis and beta-oxidation and prevents hepatic tissue from liver damage and NAFLD.

A high-fat diet differentially affects the gut metabolism and blood lipids of rats depending on the type of dietary fat and carbohydrate

The aim of this model study was to investigate how selected gut functions and serum lipid profile in rats on high-fat diets differed according to the type of fat (saturated vs. unsaturated) and carbohydrate (simple vs. complex). The experiment was conducted using 32 male Wistar rats distributed into 4 groups of 8 animals each. For 4 weeks, the animals were fed group-specific diets that were either rich in lard or soybean oil (16% of the diet) as the source of saturated or unsaturated fatty acids, respectively; further, each lard- and soybean oil-rich diet contained either fructose or corn starch (45.3% of the diet) as the source of simple or complex carbohydrates, respectively. Both dietary factors contributed to changes in the caecal short-chain fatty acid concentrations, especially to the butyrate concentration, which was higher in rats fed lard- and corn starch-rich diets compared to soybean oil- and fructose-rich diets, respectively. The lowest butyrate concentration was observed in rats fed the soybean oil- and fructose-rich diet. On the other hand, the lard- and fructose-rich diet vs. the other dietary combinations significantly increased serum total cholesterol concentration, to more than two times serum triglyceride concentration and to more than five times the atherogenic index. In conclusion, a high-fat diet rich in fructose can unfavorably affect gut metabolism when unsaturated fats are predominant in the diet or the blood lipids when a diet is rich in saturated fats.