Hepatic Energy Metabolism Underlying Differential Lipidomic Responses to High-Carbohydrate and High-Fat Diets in Male Wistar Rats

α-Lipoic acid - a promising agent for attenuating inflammation and preventing steatohepatitis in rats fed a high-fat diet

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver disorder affecting a significant part of the global population. This study aimed to investigate the potential therapeutic effects of α-lipoic acid (α-LA) on the inflammatory response during simple steatosis development and progression into steatohepatitis. The study used the MASLD model in male Wistar rats that were fed a standard diet or a high-fat diet (HFD) for 8 weeks. Throughout the entire experiment, half of the animals received α-LA supplementation. The hepatic activity of pro-inflammatory n-6 and anti-inflammatory n-3 polyunsaturated fatty acid (PUFA) pathways and the concentration of arachidonic acid (AA) in selected lipid fractions were determined by the gas-liquid chromatography (GLC). The hepatic expression of proteins from inflammatory pathway was measured by the Western blot technique. The level of eicosanoids, cytokines and chemokines was assessed by the ELISA or multiplex assay kits. The results showed that α-LA supplementation attenuated the activity of n-6 PUFA pathway in FFA and DAG and increased the activity of n-3 PUFA pathway in PL, TAG and DAG. In addition, the administration of α-LA decreased the concentration of AA in DAG and FFA, indicating its potential protective effect on the deterioration of simple hepatic steatosis. The supplementation of α-LA also increased the expression of COX-1 and COX-2 with the lack of significant changes in prostaglandins profile. We observed an increase in the expression of 12/15-LOX, which was reflected in an increase in lipoxin A4 (LXA4) level. A decrease in pro-inflammatory cytokines and an increase in anti-inflammatory cytokines was also noticed in the liver of rats treated with HFD and α-LA. Our observations confirm that α-LA treatment has potential protective effects on inflammation development in the MASLD model. We believe that α-LA has a preventive impact when it comes to the progression of simple steatosis lesions to steatohepatitis.

A very high-carbohydrate diet differentially affects whole-body glucose tolerance and hepatic insulin resistance in rats

OBJECTIVES

This study was performed to assess the effects of long-term intake of a very high carbohydrate (VHCHO) diet (76% of total energy from carbohydrate [CHO]) on whole-body glucose tolerance and hepatic insulin resistance.

METHODS AND MATERIALS

Male Sprague Dawley rats were fed either a control high-CHO diet (59% total energy from CHO; n = 8) or a VHCHO diet (76% total energy from CHO; n = 8) for 17 wk. At 4, 8, 12, and 16 wk of the dietary intervention, oral glucose tolerance test and homeostasis model assessment of insulin resistance (HOMA-IR) measurements were taken to assess whole-body glucose tolerance and hepatic insulin resistance, respectively. The triacylglycerol concentration in the liver was measured at the end of the 17-wk intervention period.

RESULTS

The VHCHO diet group showed significantly higher muscle glucose transporter 4 content and a smaller area under the curve for plasma glucose, but not insulin, in the oral glucose tolerance test compared with the control group. On the other hand, the VHCHO diet group had a significantly higher hepatic triacylglycerol concentration and HOMA-IR measurement compared with the control group. The hepatic triacylglycerol concentration was significantly and positively correlated with HOMA-IR.

CONCLUSIONS

The results of the present study suggest that long-term intake of a VHCHO diet exerts differential effects on whole-body glucose tolerance and hepatic insulin resistance.

Nucleoside diphosphate kinases 1 and 2 regulate a protective liver response to a high-fat diet

The synthesis of fatty acids from acetyl-coenzyme A (AcCoA) is deregulated in diverse pathologies, including cancer. Here, we report that fatty acid accumulation is negatively regulated by nucleoside diphosphate kinases 1 and 2 (NME1/2), housekeeping enzymes involved in nucleotide homeostasis that were recently found to bind CoA. We show that NME1 additionally binds AcCoA and that ligand recognition involves a unique binding mode dependent on the CoA/AcCoA 3' phosphate. We report that Nme2 knockout mice fed a high-fat diet (HFD) exhibit excessive triglyceride synthesis and liver steatosis. In liver cells, NME2 mediates a gene transcriptional response to HFD leading to the repression of fatty acid accumulation and activation of a protective gene expression program via targeted histone acetylation. Our findings implicate NME1/2 in the epigenetic regulation of a protective liver response to HFD and suggest a potential role in controlling AcCoA usage between the competing paths of histone acetylation and fatty acid synthesis.

Effect of virgin coconut oil on body weight, white fat depots, and biochemical and morphological parameters in mice fed standard or high-fat diets

This study investigated the effects of virgin coconut oil (VCO) on body weight, white fat depots, and biochemical and morphological parameters in male Swiss mice fed standard (SD) or high-fat (HFD) diets. Thirty-three adult animals were assigned to one of four groups, as follows: SD, SD plus VCO (SDCO), HFD, and HFD plus VCO (HFDCO). VCO had no effects on the Lee index, subcutaneous fat, periepididymal fat, retroperitoneal fat, area under the curve for glucose, or pancreas weight, all of which were increased by HFD. Low-density lipoprotein cholesterol increased in the SDCO group compared with the SD group and decreased in the HFDCO group compared with the HFD group. VCO increased total cholesterol only in the SDCO group compared with the SD group, with no differences between the HFD and HFDCO groups. In conclusion, low-dose VCO supplementation did not improve obesity, had no effects on hepatic or renal function, and had beneficial effects on the lipid profile only in animals fed HFD.

Metabolomics Reveal the Regulatory Effect of Polysaccharides from Fermented Barley Bran Extract on Lipid Accumulation in HepG2 Cells

Barley bran has potential bioactivities due to its high content of polyphenols and dietary fiber, etc. Fermentation has been considered as an effective way to promote the functional activity of food raw materials. In this study, polysaccharides from barley bran extract fermented by Lactiplantibacillus plantarum dy-1 (FBBE-PS) were analyzed, and its effects on lipid accumulation and oxidative stress in high-fat HepG2 cells induced by sodium oleate were evaluated. The results showed that the molecular weight decreased and monosaccharide composition of polysaccharides changed significantly after fermentation. In addition, 50 μg/mL FBBE-PS could reduce the triglyceride (TG) content and reaction oxygen species (ROS) level in high-fat HepG2 cells by 21.62% and 30.01%, respectively, while increasing the activities of superoxide dismutase (SOD) and catalase (CAT) represented by 64.87% and 22.93%, respectively. RT-qPCR analysis revealed that FBBE-PS could up-regulate the lipid metabolism-related genes such as ppar-α, acox-1 and cpt-1α, and oxidation-related genes such as nrf2, ho-1, nqo-1, sod1, cat, etc. The metabolomics analysis indicated that FBBE-PS could alleviate lipid deposition by inhibiting the biosynthesis of unsaturated fatty acids, which is consistent with the downregulation of scd-1 expression. It is demonstrated that fermentation can alter the properties and physiological activities of polysaccharides in barley bran, and FBBE-PS exhibited an alleviating effect on lipid deposition and oxidative stress in high-fat cells.

The hypolipidemic mechanism of chrysanthemum flavonoids and its main components, luteolin and luteoloside, based on the gene expression profile

In this study, the following four groups of mice with hyperlipidemia were involved: the model control group (MC), the Chrysanthemum flavonoids group (CF), the luteolin group, and the luteoloside group. The whole gene expression profile was detected in the liver tissues of each group. Differential genes significantly enriched in the biological process of gene ontology (GO) items and Kyoto Encyclopedia of Genes and Genomes (KEGG) were selected, and 4 differential genes related to lipid metabolism were selected for further real-time quantitative PCR verification. Compared with the MC, 41 differential genes such as Sqle, Gck, and Idi1 were screened in the CF intervention group; 68 differential genes such as Acsl3, Cyp7a1, and Lpin1 were screened in the luteolin intervention group (CF); and 51 differential genes such as Acaca, Cyp7a1, and Lpin1 were screened in the luteoloside group. The mechanism of CF to improve hyperlipidemia is very complex, mainly involving biological processes such as cholesterol and fatty acid metabolism and glycolysis, luteolin mainly involves the synthesis and transport of cholesterol, and luteoloside mainly involves fatty acid metabolism. The functional pathways of CF may not be completely the same as luteolin and luteoloside, and further study is needed on the mechanism of action of other components.

Lipidomics Reveals That Rice or Flour as a Single Source of Carbohydrates Cause Adverse Health Effects in Rats

The type of diet is very important for the maintenance of health and nutrition. How the sole source of carbohydrates from rice- or flour-based diet affect blood sugar has not been elucidated for a long time. In order to explore the effects of these diets, sixty SD rats were randomly divided into three groups: control group (C group, AIN-93, standard diet), rice diet group (R group), and flour diet group (F group). All the rats were fed for 7 weeks in total by the assigned diets for 4 weeks (stage 1, S1) and all by the AIN-93 diet for 3 weeks (stage 2, S2). The body weights of all the rats were monitored and serum samples were taken for testing blood glucose, biochemical indicators and untargeted lipidome. It was found that both rice and flour-based diets caused weight gain, but the flour diet had a significant increase in blood sugar and low-density lipoprotein (LDL), while a significant decrease in albumin (ALB) and triglycerides (TG). Twenty-three and 148 lipids were changed by lipidomics in the rice diet group and flour diet group, respectively, and two lipids showed the same changes in the two groups, all belonging to TGs, namely TG (16:0/16:0/16:1) and TG (16:0/16:1/18:2), which showed that a single diet source had a significant effect on the health of rats. Fortunately, we can recover this effect through the subsequent standard diet, allowing the rats to return to normal blood sugar, weight and biochemical indicators. A model can predict the diet types through the logistic regression method. Finally, we proposed that a single diet increased blood sugar and weight through a decrease in TGs, and blood sugar and weight returned to normal after a standard diet. Taken together, the short-term negative effects caused by a single diet can be recovered by a standard diet and further proves the importance of diet types.