Hepatic Lipogenesis and Brain Fatty Acid Profile in Response to Different Dietary n6/n3 Ratios and DHA/EPA Supplementation in Streptozotocin Treated Rats

Beneficial effects of procyanidin B2 on adriamycin-induced nephrotic syndrome mice: the multi-action mechanism for ameliorating glomerular permselectivity injury

Despite considerable advances in prevention, diagnosis, and therapy, nephrotic syndrome (NS) remains a significant cause of high morbidity and mortality globally. As a result, there is an urgent need to identify novel effective preventative and therapeutic agents for NS. NS is implicated in glomerular permselectivity injury, which can be attributed to oxidative distress, inflammation, lipid nephrotoxicity, podocyte apoptosis, autophagy dysfunction, and slit diaphragm (SLD) dysfunction. In addition to its well-documented antioxidant potency, procyanidin B2 (PB2) may exhibit pleiotropic effects by targeting various canonical signaling events, such as NF-κB, PPARs, PI3K/Akt, mTOR, and the caspase family. As a result, PB2 may be a promising therapeutic target against NS. To test this hypothesis, we established an Adriamycin (ADR)-induced NS mouse model to evaluate the pleiotropic renoprotective effects of PB2 on NS. Here, we demonstrated that PB2 improves podocyte injury via inhibition of NOX4/ROS and Hsp90/NF-κB to exhibit antioxidant and anti-inflammatory potency, respectively. We also show that PB2 indirectly activates the PI3K/Akt axis by regulating SLD protein levels, resulting in normalized podocyte apoptosis and autophagy function. Further, loss of albumin (ALB) induces lipid nephrotoxicity, which we found to be alleviated by PB2 via activation of PPARα/β-mediated lipid homeostasis and the cholesterol efflux axis. Interestingly, our results also suggested that PB2 reduces electrolyte abnormalities and edema. In addition, PB2 may contribute protective effects against trace element dys-homeostasis, which, through alleviating serum ALB loss, leads to a protective effect on glomerular permselectivity injury. Taken together, our results reveal that the identified mechanisms of PB2 on NS are multifactorial and involve inhibition of oxidative distress and inflammatory responses, as well as improvements in podocyte apoptosis and autophagy dysfunction, amelioration of lipid nephrotoxicity, and modulation of electrolyte abnormalities and edema. Thus, we provide a theoretical basis for the clinical application of PB2 against NS.

Foxtail Millet Improves Blood Glucose Metabolism in Diabetic Rats through PI3K/AKT and NF-κB Signaling Pathways Mediated by Gut Microbiota

Foxtail millet (FM) is receiving ongoing increased attention due to its beneficial health effects, including the hypoglycemic effect. However, the underlying mechanisms of the hypoglycemic effect have been underexplored. In the present study, the hypoglycemic effect of FM supplementation was confirmed again in high-fat diet and streptozotocin-induced diabetic rats with significantly decreased fasting glucose (FG), glycated serum protein, and areas under the glucose tolerance test (p < 0.05). We employed 16S rRNA and liver RNA sequencing technologies to identify the target gut microbes and signaling pathways involved in the hypoglycemic effect of FM supplementation. The results showed that FM supplementation significantly increased the relative abundance of Lactobacillus and Ruminococcus_2, which were significantly negatively correlated with FG and 2-h glucose. FM supplementation significantly reversed the trends of gene expression in diabetic rats. Specifically, FM supplementation inhibited gluconeogenesis, stimulated glycolysis, and restored fatty acid synthesis through activation of the PI3K/AKT signaling pathway. FM also reduced inflammation through inhibition of the NF-κB signaling pathway. Spearman’s correlation analysis indicated a complicated set of interdependencies among the gut microbiota, signaling pathways, and metabolic parameters. Collectively, the above results suggest that the hypoglycemic effect of FM was at least partially mediated by the increased relative abundance of Lactobacillus, activation of the PI3K/AKT signaling pathway, and inhibition of the NF-κB signaling pathway.

Fatty Acids and Cardiovascular Risk. Evidence, Lack of Evidence, and Diligence

One of the most controversial areas of nutrition research relates to fats, particularly essential fatty acids, in the context of cardiovascular disease risk. A critical feature of dietary fatty acids is that they incorporate into the plasma membrane, modifying fluidity and key physiological functions. Importantly, they can reshape the bioavailability of eicosanoids and other lipid mediators, which direct cellular responses to external stimuli, such as inflammation and chronic stress conditions. This paper provides an overview of the most recent evidence, as well as historical controversies, linking fat consumption with human health and disease. We underscore current pitfalls in the area of fatty acid research and critically frame fatty acid intake in the larger context of diet and behavior. We conclude that fundamental research on fatty acids and lipids is appropriate in certain areas, but the rigor and reproducibility are lacking in others. The pros and cons are highlighted throughout the review, seeking to guide future research on the important area of nutrition, fat intake, and cardiovascular disease risk.

Cafeteria Diet and High-Fructose Rodent Models of NAFLD Differ in the Metabolism of Important PUFA and Palmitoleic Acid without Additional Influence of Sex

The objective of this study was to evaluate the influence of high-fat (HF) and cafeteria diet (CAF) diets and sex on the metabolism of important fatty acids in the liver and perirenal fat tissue. Dietary treatments induced changes in the fatty acid profile in comparison to the untreated group, but the characteristic differences between treated groups were also observable. The HF diet induced an increase in the content of C16:1n-7 and C18:1n-7 in the liver phospholipids (PL) and triglycerides (TG) and perirenal fat tissue compared to the control and CAF diet. The CAF diet induced a more drastic decrease in both n-3 and n-6 polyunsaturated fatty acids (PUFA), including depletion of eicosapentaenoic acid (EPA). The CAF diet also increased the content of n-6 docosapentaenoic acid (DPAn-6) in the liver and decreased it in the perirenal fat. Sex also had a significant influence on the fatty acid profile, but the variables with the highest differences between the CAF and HF treatments were identical in the male and female rats. In this study, we have established that two dietary models of non-alcoholic fatty liver disease (NAFLD) led to characteristic changes in the hepatic and perirenal fat fatty acid profile, in contrast to the control diet and in comparison with each other. These differences could play an important role in the interpretation of the experimental results of nutritional studies.

Effects of Different n6/n3 PUFAs Dietary Ratio on Cardiac Diabetic Neuropathy

We studied the influence of experimentally induced DM1, in combination with different dietary n6:n3 polyunsaturated fatty acid (PUFA) ratios on different types of nerve fibers in rat myocardium, in order to reveal whether protective/unfavorable effects of different PUFAs on myocardial function in diabetic patients could be a (partial) repercussion of their effect on the changes in cardiac innervation. The control group (c) and diabetic group (stz) were fed with an n6/n3 ratio of ≈7; the diet of the stz+n6 group had an n6/n3 ratio ≈60, while the diet for the stz+DHA group contained 2.5% of fish oil (containing 16% eicosapentaenoic acid—EPA and 19% docosahexaenoic acid—DHA), n6/n3 ratio of ≈1. DM1 was induced by i.p. injection of streptozotocin (55 mg/kg) and rats were euthanized 30 days after induction. Immunohistochemistry was used for the detection and quantification of different types of neuronal fibers in the cardiac septum. We found changes in cardiac innervations characteristics for the initial phase of experimental DM1, which manifested as an increase in total number and area density of all neuronal fibers, measured by Pgp9.5 immunoreactivity. By detailed analysis, we found that this increase consisted mostly of heavy myelinated NF200 immunoreactive fibers and TH immunoreactive sympathetic fibers, while the density of ChAT immunoreactive parasympathetic fibers decreased. In the deep (middle) part of the myocardium, where rare fibers (of all studied types) were found, significant differences were not found. Surprisingly, we found a more consistent protective effect of n6 PUFAs, in comparison to n3 PUFAs supplementation. These results may provide a better understanding of the potential impacts of different PUFA ratios in the diet of diabetic patients on cardiac innervation and genesis and outcome of diabetic autonomic cardiomyopathy.

Dietary fatty acids and CD36-mediated cholesterol homeostasis: potential mechanisms

Currently, the prevention and treatment of CVD have been a global focus since CVD is the number one cause of mortality and morbidity. In the pathogenesis of CVD, it was generally thought that impaired cholesterol homeostasis might be a risk factor. Cholesterol homeostasis is affected by exogenous factors (i.e. diet) and endogenous factors (i.e. certain receptors, enzymes and transcription factors). In this context, the number of studies investigating the potential mechanisms of dietary fatty acids on cholesterol homeostasis have increased in recent years. As well, the cluster of differentiation 36 (CD36) receptor is a multifunctional membrane receptor involved in fatty acid uptake, lipid metabolism, atherothrombosis and inflammation. CD36 is proposed to be a crucial molecule for cholesterol homeostasis in various mechanisms including absorption/reabsorption, synthesis, and transport of cholesterol and bile acids. Moreover, it has been reported that the amount of fatty acids and fatty acid pattern of the diet influence the CD36 level and CD36-mediated cholesterol metabolism principally in the liver, intestine and macrophages. In these processes, CD36-mediated cholesterol and lipoprotein homeostasis might be impaired by dietary SFA and trans-fatty acids, whereas ameliorated by MUFA in the diet. The effects of PUFA on CD36-mediated cholesterol homeostasis are controversial depending on the amount of n-3 PUFA and n-6 PUFA, and the n-3:n-6 PUFA ratio. Thus, since the CD36 receptor is suggested to be a novel nutrient-sensitive biomarker, the role of CD36 and dietary fatty acids in cholesterol metabolism might be considered in medical nutrition therapy in the near future. Therefore, the novel nutritional target of CD36 and interventions that focus on dietary fatty acids and potential mechanisms underlying cholesterol homeostasis are discussed in this review.

The Nootropic Drug Α-Glyceryl-Phosphoryl-Ethanolamine Exerts Neuroprotective Effects in Human Hippocampal Cells

Brain aging involves changes in the lipid membrane composition that lead to a decrease in membrane excitability and neurotransmitter release. These membrane modifications have been identified as contributing factors in age-related memory decline. In this sense, precursors of phospholipids (PLs) can restore the physiological composition of cellular membranes and produce valuable therapeutic effects in brain aging. Among promising drugs, alpha-glycerylphosphorylethanolamine (GPE) has demonstrated protective effects in amyloid-injured astrocytes and in an aging model of human neural stem cells. However, the compound properties on mature neuronal cells remain unexplored. Herein, GPE was tested in human hippocampal neurons, which are involved in learning and memory, and characterized by a functional cholinergic transmission, thus representing a valuable cellular model to explore the beneficial properties of GPE. GPE induced the release of the main membrane phospholipids and of the acetylcholine neurotransmitter. Moreover, the compound reduced lipid peroxidation and enhanced membrane fluidity of human brain cells. GPE counteracted the DNA damage and viability decrease observed in in vitro aged neurons. Among GPE treatment effects, the autophagy was found positively upregulated. Overall, these results confirm the beneficial effects of GPE treatment and suggest the compound as a promising drug to preserve hippocampal neurons and virtually memory performances.

Proliferation of C6 glioma cells requires the phospholipid remodeling enzyme tafazzin independent of cardiolipin composition

The mitochondrial phospholipid (CL) has been linked to mitochondrial and cellular functions. It has been postulated that the composition of CL is of impact for mitochondrial energy metabolism and cell proliferation. Although a correlation between CL composition and proliferation could be demonstrated for several cell types, evidence for a causal relationship remains obscure. Here, we applied two independent approaches, i) supplementation of fatty acids and ii) knock-out of the phospholipid remodeling enzyme tafazzin, to manipulate CL composition and analyzed the response on proliferation of C6 glioma cells. Both strategies caused substantial changes in the distribution of cellular fatty acids as well as in the distribution of fatty acids incorporated in CL that were accompanied by changes of the composition of molecular CL species. These changes did not correlate with cell proliferation. However, knock-out of tafazzin caused dramatic reduction in proliferation of C6 glioma cells independent of CL composition. The mechanism of tafazzin-dependent restriction of proliferation remains unclear. Among the various fatty acids administered only palmitic acid restricted cell proliferation by induction of cell death.

PUFAs supplementation affects the renal expression of pannexin 1 and connexins in diabetic kidney of rats

In diabetic nephropathy (DN), intercellular communication is disrupted. Connexins (Cx) have a crucial role in that process. Dietary ratios and supplementation with polyunsaturated fatty acids (PUFAs) can alleviate diabetic complications and cause alterations in Cx levels. Although pannexins (Panx) share similarities with members of the Cx family, their function in diabetic nephropathy has still not been fully determined. We studied the influence of PUFA supplementation on the immunoexpression of Px1 and Cx family members in diabetic kidneys of rats. Four groups of rats in experimental DM1 model were supplemented with different dietary n-6/n-3 ratios; ≈7 in control (C) and diabetic groups (STZ), ≈ 60 in the STZ + N6 group and ≈ 1 (containing 16% EPA and 19% DHA) in the STZ + N3 group. Immunoexpression of Cx40, Cx43, Cx45 and Panx1 was evaluated in the renal tissue of diabetic rats using immunohistochemistry. Diabetes significantly decreased the protein expression of Cx40 and Cx43 and increased Panx1 protein expression in the renal cortex (p < 0.05-p < 0.01). There was a significant impact of diet on Cx and Panx1 immunoexpression. Dietary supplementation with a high n-6/n-3 ratio downregulated the protein expression of Cx45 and Panx1 in diabetic rats (p < 0.05-p < 0.01), while Cx43 immunoexpression was increased in diabetic rats fed with high and low n-6/n-3 ratios (p < 0.01-p < 0.001). Hyperglycaemic conditions in DN interfere with cell-to-cell communication and disturb the connection between cells and their immediate environment due to variations in connexin and pannexin immunoexpression. These variations can be regulated by PUFA dietary intake, suggesting their beneficial effect and possible therapeutic option.

Degree of lipid saturation affects depressive-like behaviour and gut microbiota in mice

This study explored the effects of the degree of lipid saturation on depressive behaviour and gut microbiota in mice. Thirty-two mice were divided into normal (N), Prozac (NP), lard (L) and fish oil (F) groups. After a 12-week dietary intervention, the open field test (OFT) and the forced swim test (FST) were conducted before sacrifice. The mice in the L group exhibited anxiety-like behaviours in the OFT and depressive-like behaviours in the FST. A significant difference was observed in β-diversity indices between the L group and the F group. The abundance of Allobaculum and Bifidobacterium was significantly higher in the F group than in the L and N groups. The prefrontal cortex fatty acid composition was altered in various lipid-treated groups and was highly correlated with depressive-like behaviours. In conclusion, the degree of lipid saturation affects depressive-like behaviour, gut microbiota composition, and the prefrontal cortex fatty acid profile in mice.

High dietary n6/n3 ratio decreases eicosapentaenoic to arachidonic acid ratios and upregulates NFκB/p50 expression in short-term low-dose streptozotocin and high-fructose rat model of diabetes

We studied the influence of dietary n6/n3 ratio and docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids supplementation on fatty acid profile, lipid peroxidation and NFκ/p50 expression in diabetes type 2. Treatments consisted of three dietary n6/n3 ratios: 6 (Control), 50 (high n6) and 1 (DHA and EPA supplemented). Half of the rats in each of the dietary treatments were made diabetic using the fructose/low-streptozotocin model. The Control and high n6 diets decreased EPA/ARA (arachidonic acid) ratios in the plasma and in the hepatic tissue suggesting proinflammatory fatty acid profile. The high n6 diet additionally increased the 4-HNE and NFκ/p50 expression in the hepatic tissue. These changes were the consequence of a decrease in the plasma content of DHA and EPA and an increase in the content of arachidonic acid in the liver neutral lipids. The supplementation with the DHA and EPA attenuated the change in EPA/ARA ratios, which imply the importance of the n6/n3 ratio in diabetes type 2.

Dietary DHA/EPA supplementation ameliorates diabetic nephropathy by protecting from distal tubular cell damage

The aim was to explore the influence of experimental diabetes mellitus type 1 (DM1) and potential protective/deleterious effects of different dietary n-6/n-3 PUFA ratios on renal phospholipid composition and pathological changes caused by DM1. Male Wistar rats were injected with 55 mg/kg streptozotocin or citrate buffer (control group). Control (C) and diabetic groups (STZ) were fed with n-6/n-3 ratio of ≈ 7, STZ + N6 with n-6/n-3 ratio ≈ 60 and STZ + DHA with n-6/n-3 ratio of ≈ 1 containing 16% EPA and 19% DHA. Tissues were harvested 30 days after DM1 induction. Blood and kidneys were collected and analysed for phospholipid fatty acid composition, pathohystological changes, ectopic lipid accumulation and expression of VEGF, NF-kB and special AT-rich sequence-binding protein-1 (SATB1). Pathological changes were studied also by using transmission electron microscopy, after immunostaining for VEGF. Substantial changes in renal phospholipid fatty acid composition resulted from DM1 and dietary PUFA manipulation. Extensive vacuolization of distal tubular cells (DTCs) was found in DM1, but it was attenuated in the STZ + DHA group, in which the highest renal NF-kB expression was observed. The ectopic lipid accumulation was observed in proximal tubular cells (PTCs) of all diabetic animals, but it was worsened in the STZ + N6 group. In DM1, we found disturbance of VEGF-transporting vesicular PTCs system, which was substantially worsened in STZ + DHA and STZ + N6. Results have shown that the early phase of DN is characterized with extent damage and vacuolization of DTCs, which could be attenuated by DHA/EPA supplementation. We concluded that dietary fatty acid composition can strongly influence the outcomes of DN.

Mangiferin improves hepatic damage-associated molecular patterns, lipid metabolic disorder and mitochondrial dysfunction in alcohol hepatitis rats

This study was conducted to investigate the beneficial effects and possible mechanism of action of mangiferin (MF) in alcohol hepatitis (AH) rats. Building on our previous study, the damage-associated molecular patterns (DAMPs), lipid metabolic disorder and mitochondrial dysfunction were investigated. MF effectively regulated the abnormal liver function, the levels of alcohol, FFAs and metal elements in serum. More importantly, MF improved the expression levels of mRNA and protein of PPAR-γ, OPA-1, Cav-1, EB1, NF-κB p65, NLRP3, Cas-1 and IL-1β, and decreased the positive protein expression rates of HSP90, HMGB1, SYK, CCL20, C-CAS-3, C-PARP and STARD1. Additionally, MF decreased the levels of fumarate, cAMP, xanthurenic acid and d-glucurone-6,3-lactone, and increased the levels of hippuric acid and phenylacetylglycine, and then adjusted the changes of phenylalanine metabolism, TCA cycle and ascorbate and aldarate metabolic pathways. The above results suggested that MF can effectively prevent AH by modulating specific AH-associated genes, potential biomarkers and metabolic pathways in AH rats, etc.