Lipoic acid suppresses portal endotoxemia-induced steatohepatitis and pancreatic inflammation in rats

High Starch Induces Hematological Variations, Metabolic Changes, Oxidative Stress, Inflammatory Responses, and Histopathological Lesions in Largemouth Bass (Micropterus salmoides)

This study evaluated effects of high starch (20%) on hematological variations, glucose and lipid metabolism, antioxidant ability, inflammatory responses, and histopathological lesions in largemouth bass. Results showed hepatic crude lipid and triacylglycerol (TAG) contents were notably increased in fish fed high starch. High starch could increase counts of neutrophils, lymphocytes, monocytes, eosinophils, and basophils and serum contents of TAG, TBA, BUN, and LEP (p < 0.05). There were increasing trends in levels of GLUT2, glycolysis, gluconeogenesis, and LDH in fish fed high starch through the AKT/PI3K signal pathway. Meanwhile, high starch not only triggered TAG and cholesterol synthesis, but mediated cholesterol accumulation by reducing ABCG5, ABCG8, and NPC1L1. Significant increases in lipid droplets and vacuolization were also shown in hepatocytes of D3-D7 groups fed high starch. In addition, high starch could decrease levels of mitochondrial Trx2, TrxR2, and Prx3, while increasing ROS contents. Moreover, high starch could notably increase amounts of inflammatory factors (IL-1β, TNF-α, etc.) by activating NLRP3 inflammasome key molecules (GSDME, caspase 1, etc.). In conclusion, high starch could not only induce metabolic disorders via gluconeogenesis and accumulation of glycogen, TAG, and cholesterol, but could disturb redox homeostasis and cause inflammatory responses by activating the NLRP3 inflammasome in largemouth bass.

Pumpkin seed proteins (Cucurbita pepo L.) protect against diet-induced metabolic syndrome by improving insulin resistance and markers of oxidative stress and inflammation in rats

Pumpkin (Cucurbita pepo L.) seeds are enriched in bioactive compounds having functional properties. The aim of this study was to analyze the pumpkin seed proteins (PSP) effects on insulin resistance, oxidative stress damage and inflammation in rats with high fructose-induced metabolic syndrome.

Twenty four male Wistar rats, fed isoenergetic diets supplemented with: (1) 20% casein (C); (2) 20% casein and 1 g/kg/day PSP (P); (3) 20% casein and 64% D-fructose (C-HF); (4) 20% casein, 1 g/kg/day PSP and 64% D-fructose (P-HF). After 8 weeks of treatment, fructose supply impaired white adipose tissue (WAT) weight, deteriorated glucose tolerance and tAUC, plasma glucose, insulin, insulinogenic index, HOMA-IR and HOMA-β, antioxidant status, lipid and protein oxidation, plasma TNF-α and IL-6 as compared to control diets. Interestingly, rats assigned to the PSPs diet with or without fructose displayed lower plasma glucose, insulin and fructose, improved tolerance of glucose, tAUC, HOMA-IR and HOMA-β and increased insulinogenic index as compared to C diets. PSPs consumption lowered thiobarbituric acid reactive substances, hydroperoxides and carbonyls in WAT and carbonyls in muscle. Superoxide dismutase and glutathione peroxidase in WAT were significantly diminished in P-HF but increased in P as compared to C-HF and C. Rats fed P-HF diet had low catalase in WAT and high in muscle than those fed C-HF. Moreover, catalase activity increased in muscle but decreased in WAT in P group than in C group. In conclusion, pumpkin seed proteins exhibit favorable effects on metabolic disorders of fructose-induced metabolic syndrome, suggesting a key role in disease therapy.

The effect of lipoic acid on the content of SOD-1 and TNF-α in rat striated muscle

Background

The aim of the study was to present the effect of lipoic acid (LA) on oxidative stress induced by lipopolysaccharide (LPS).

Materials/Methods

The studies were conducted on male rats of the Wistar strain. The animals were divided into four groups. I: the controls received saline (0.2 ml); II: LPS, received LPS (Escherichia coli 026: B6) at a dose of 6 mg/kg body weight; III: LA, received LA at a dose of 60 mg/kg body weight; IV: LA + LPS, received LA (60 mg/kg b.w.) and after 30 min received LPS (6 mg/kg b.w.). All compounds were administered to the tail vein. After 5 hours of the experiment, the animals were anesthetized and striated muscle from the thigh was prepared. The isolated muscle was homogenized. Concentrations of superoxide dismutase-1 (SOD-1) and tumor necrosis factor alpha (TNF-α) were determined in the homogenates with the application of ELISA.

Results

The study showed a significant decrease in SOD-1 content and an increase in TNF-α in striated muscle after LPS administration. LA given 30 min before administration of LPS caused a significant increase in the level of SOD-1 and decreased levels of TNF-α in homogenates.

Conclusion

LA reduced the parameters of LPS oxidative stress, thus contributing to an increase in the body's antioxidant defense.

The Protective Role of Prenatal Alpha Lipoic Acid Supplementation against Pancreatic Oxidative Damage in Offspring of Valproic Acid-Treated Rats: Histological and Molecular Study

Background: Sodium valproate (VPA) is an antiepileptic drug (AED) licensed for epilepsy and used during pregnancy in various indications. Alpha-lipoic acid (ALA) is a natural compound inducing endogenous antioxidant production. Our study aimed to investigate the effect of prenatal administration of VPA on the pancreas of rat offspring and assess the potential protective role of ALA co-administration during pregnancy. Methods: Twenty-eight pregnant female albino rats were divided into four groups: group I (negative control), group II (positive control, ALA treated), group III (VPA-treated), and group IV (VPA-ALA-treated). The pancreases of the rat offspring were removed at the fourth week postpartum and prepared for histological, immune-histochemical, morphometric, molecular, and oxidative stress marker studies. Results: In group III, there were pyknotic nuclei, vacuolated cytoplasm with ballooning of acinar, α, and β cells of the pancreas. Ultrastructural degeneration of cytoplasmic organelles was detected. Additionally, there was a significant increase in oxidative stress, a decrease in insulin-positive cell percentage, and an increase in glucagon positive cells in comparison to control groups. Moreover, VPA increased the gene expression of an apoptotic marker, caspase-3, with a decrease in anti-apoptotic Bcl2 and nuclear factor erythroid 2-related factor 2 (Nrf2) transcriptional factor. Conversely, ALA improved oxidative stress and apoptosis in group VI, and a consequent improvement of the histological and ultrastructure picture was detected. Conclusion: ALA co-administration with VPA significantly improved the oxidative stress condition, histological and morphometric picture of the pancreas, and restored normal expression of related genes, including Nrf2, caspase-3, and Bcl-2. Administration of α-lipoic acid has a protective effect against VPA-induced pancreatic oxidative damage via its cytoprotective antioxidant effect.

HMGB1 is increased in adolescents with polycystic ovary syndrome (PCOS) and decreases after treatment with myo-inositol (MYO) in combination with alpha-lipoic acid (ALA)

PCOS treatment should be based on pathophysiology. High-mobility-group-box-1 (HMGB1) was shown to increase in PCOS patients as a consequence of reduced cystic-fibrosis-transmembrane-conductance-regulator (CFTR) expression in the ovary, and was associated with insulin resistance and inflammation, both features of PCOS. Inositols and ALA derivatives could have positive effects on insulin sensitivity, reduce androgens, and improve ovulation rhythm. The aim of this study was to verify changes in HMGB1, in metabolic and endocrine parameters in adolescents with PCOS compared with controls and after treatment with a combination of MYO + ALA. Twenty-three PCOS adolescents and 21 controls matched for age and BMI were enrolled. In all subjects, metabolic and hormonal parameters were assayed. Homeostatic index (HOMA-IR) and the triglyceride/HDL-cholesterol ratio were calculated. Ovarian volumes were evaluated. Patients were treated with MYO + ALA for 6 months. HMGB1 was measured using a specific ELISA assay. HMGB1 was increased in PCOS compared with controls (19.76 ± 5.99 versus 5.65 ± 1.88 ng/ml; p < .05) and normalized after treatment (2.27 ± 0.36 ng/ml, p < .05). Treatment significantly reduced insulin (24.0 ± 4.11 versus 12.13 ± 2.13 uU/ml), HOMA-IR (3.91 ± 0.41 versus 2.42 ± 0.45), and 17-hydroxyprogesterone (1.20 ± 0.15 versus 0.78 ± 0.11 ng/ml). Cholesterol, luteinizing hormone, 17-β-estradiol, delta 4-androstenedione, and testosterone were unchanged. Circulating HMGB1 was increased in PCOS adolescents, and treatment was effective in normalizing HMGB1.

Alpha-lipoic acid and its protective role in fructose induced endocrine-metabolic disturbances

In recent decades a worldwide increase has been reported in the consumption of unhealthy high calorie diets associated with marked changes in meal nutrient composition, such as a higher intake of refined carbohydrates, which leads to the speculatation that changes in food habits have contributed to the current epidemic of obesity and type 2 diabetes. Among these refined carbohydrates, fructose has been deeply investigated and murine models of high fructose diet have emerged as useful tools to study dietary-induced insulin resistance, impaired glucose tolerance, dyslipidemia and alterations in glucose metabolism. Since oxidative stress has been demonstrated to play a key pathogenic role in the alterations described above, several lines of research have focused on the possible preventive effects of antioxidant/redox state regulation therapy, among which alpha-lipoic acid has been extensively investigated. The following references discussed support the fact that co-administration of alpha-lipoic acid normalized the changes generated by fructose rich diets, thereby making this compound a good therapeutic tool, also administered as a food supplement, to prevent endocrine-metabolic disturbances triggered by high fructose associated with obesity and type 2 diabetes at an early stage of development (prediabetes).

High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions

High dietary fructose is a major contributor to insulin resistance and metabolic syndrome, disturbing tissue and organ functions. Fructose is mainly absorbed into systemic circulation by glucose transporter 2 (GLUT2) and GLUT5, and metabolized in liver to produce glucose, lactate, triglyceride (TG), free fatty acid (FFA), uric acid (UA) and methylglyoxal (MG). Its extrahepatic absorption and metabolism also take place. High levels of these metabolites are the direct dangerous factors. During fructose metabolism, ATP depletion occurs and induces oxidative stress and inflammatory response, disturbing functions of local tissues and organs to overproduce inflammatory cytokine, adiponectin, leptin and endotoxin, which act as indirect dangerous factors. Fructose and its metabolites directly and/or indirectly cause oxidative stress, chronic inflammation, endothelial dysfunction, autophagy and increased intestinal permeability, and then further aggravate the metabolic syndrome with tissue and organ dysfunctions. Therefore, this review addresses fructose-induced metabolic syndrome, and the disturbance effects of direct and/or indirect dangerous factors on the functions of liver, adipose, pancreas islet, skeletal muscle, kidney, heart, brain and small intestine. It is important to find the potential correlations between direct and/or indirect risk factors and healthy problems under excess dietary fructose consumption.

Alpha-lipoic acid prevents endotoxic shock and multiple organ dysfunction syndrome induced by endotoxemia in rats

Alpha-lipoic acid (ALA), a naturally occurring disulfide derivative of octanoic acid, serves as a strong antioxidant and has been reported to possess anti-inflammatory effects. The aim of the present study is to investigate the preventive and therapeutic effects of ALA on multiple organ dysfunction syndrome (MODS) caused by endotoxemia in rats. Male Wistar rats were intravenously infused with lipopolysaccharide (LPS) (10 mg/kg) to induce endotoxemia. Alpha-lipoic acid 10, 20, or 40 mg/kg was administered intravenously 60 min before (pretreatment) LPS challenge, and ALA 40 mg/kg was administered intravenously 30 min after (posttreatment) LPS challenge. Pretreatment and posttreatment with ALA significantly improved the deleterious hemodynamic changes 8 h after LPS challenge, including hypotension and bradycardia. Alpha-lipoic acid reduced the plasma levels of glutamic pyruvic transaminase, blood urea nitrogen, lactate dehydrogenase, tumor necrosis factor-α, nitric oxide metabolites, and thrombin-antithrombin complex, which increased markedly after LPS challenge. The induction of inducible nitric oxide synthase both in the liver and the lung and vascular superoxide anion production were also significantly suppressed by ALA. Moreover, ALA significantly attenuated LPS-induced caspase-3 activation in cardiomyocytes and improved survival rate. In conclusion, ALA effectively attenuated LPS-induced acute inflammatory response and improved MODS. The antioxidant and anti-inflammatory effects of ALA may contribute to these beneficial effects. Alpha-lipoic acid might be considered as a novel therapeutic strategy in the prevention of sepsis-induced MODS and inflammatory vascular diseases.

The protective effect of lipoic acid on selected cardiovascular diseases caused by age-related oxidative stress

Oxidative stress is considered to be the primary cause of many cardiovascular diseases, including endothelial dysfunction in atherosclerosis and ischemic heart disease, hypertension, and heart failure. Oxidative stress increases during the aging process, resulting in either increased reactive oxygen species (ROS) production or decreased antioxidant defense. The increase in the incidence of cardiovascular disease is directly related to age. Aging is also associated with oxidative stress, which in turn leads to accelerated cellular senescence and organ dysfunction. Antioxidants may help lower the incidence of some pathologies of cardiovascular diseases and have antiaging properties. Lipoic acid (LA) is a natural antioxidant which is believed to have a beneficial effect on oxidative stress parameters in relation to diseases of the cardiovascular system.

Refeeding with glucose rather than fructose elicits greater hepatic inflammatory gene expression in mice

OBJECTIVE

We previously reported that refeeding after a 48-h fast, used as a study model of starvation and refeeding, promotes acute liver inflammatory gene expression, which is at least partly mediated by toll-like receptor 2 (TLR2). We also previously demonstrated that dietary carbohydrates play critical roles in this process. The aim of this study was to compare the outcomes of refeeding with different carbohydrate sources.

METHODS

Mice were fasted for 46 h and then refed with 1.5% (w/w) agar gel containing 19% carbohydrate (sources: α-cornstarch, glucose, sucrose, or fructose). The liver expression of inflammatory and other specific genes was then sequentially measured for the first 14 h after refeeding initiation.

RESULTS

Fasting for 46 h up-regulated the liver expression of endogenous ligands for TLRs (HspA5, Hsp90 aa1, and Hspd1). Refeeding with agar gel containing α-cornstarch or glucose increased the liver expression of Tlr2, proinflammatory genes (Cxcl2, Cxcl10, Cxcl1, Nfkb1, Nfkb2, RelB, Sectm1α, Il1β), stress response genes (Atf3, Asns, Gadd45 a, Perk, Inhbe), detoxification genes (Hmox1, Gsta1, Abca8b), genes involved in tissue regeneration (Gdf15, Krt23, Myc, Tnfrsf12a, Mthfd2), and genes involved in tumor suppression (p53, Txnrd1, Btg2). This refeeding also moderately but significantly elevated the serum levels of alanine aminotransferase. These effects were attenuated in mice refed with agar gel containing sucrose or fructose.

CONCLUSION

Dietary glucose, rather than fructose, plays a critical role in refeeding-induced acute liver inflammatory gene expression and moderate hepatocyte destruction. Further studies are recommended regarding the role of these effects in liver inflammation and, consequently, liver dysfunction.

Brain, liver, and serum salusin-alpha and -beta alterations in Sprague-Dawley rats with or without metabolic syndrome

BACKGROUND

This metabolic syndrome (MetS) study was designed to investigate changes in expression of the neuropeptides salusin-α (Sal-α) and salusin-β (Sal-β) in brain and liver tissue in response to obesity and related changes induced by high-fructose diet and explored how these changes were reflected in the circulating levels of Sal-α and Sal-b, as well as revealing how the lipid profile and concentrations of glucose and uric acid were altered.

MATERIAL/METHODS

The study included 14 Sprague-Dawley rats. The control group was fed ad libitum on standard rat pellets, while the intervention group was given water with 10% fructose in addition to the standard rat pellet for 3 months. Sal-α and Sal-β concentrations in the serum and tissue supernatants were measured by ELISA, and immunohistochemical staining was used to demonstrate expression of the hormones in brain and liver.

RESULTS

Sal-α and Sal-β levels in both the serum and the brain and liver tissue supernatants were lower in the MetS group than the control group. Sal-α and Sal-β were shown by immunohistochemistry to be produced in the brain epithelium, the supraoptic nucleus of the hypothalamus, and the liver hepatocytes.

CONCLUSIONS

The decrease in Sal-α and Sal-β might be involved in the etiopathology of the metabolic syndrome induced by fructose.

Alpha-lipoic acid as a pleiotropic compound with potential therapeutic use in diabetes and other chronic diseases

Alpha-lipoic acid is a naturally occurring substance, essential for the function of different enzymes that take part in mitochondria's oxidative metabolism. It is believed that alpha-lipoic acid or its reduced form, dihydrolipoic acid have many biochemical functions acting as biological antioxidants, as metal chelators, reducers of the oxidized forms of other antioxidant agents such as vitamin C and E, and modulator of the signaling transduction of several pathways. These above-mentioned actions have been shown in experimental studies emphasizing the use of alpha-lipoic acid as a potential therapeutic agent for many chronic diseases with great epidemiological as well economic and social impact such as brain diseases and cognitive dysfunctions like Alzheimer disease, obesity, nonalcoholic fatty liver disease, burning mouth syndrome, cardiovascular disease, hypertension, some types of cancer, glaucoma and osteoporosis. Many conflicting data have been found concerning the clinical use of alpha-lipoic acid in the treatment of diabetes and of diabetes-related chronic complications such as retinopathy, nephropathy, neuropathy, wound healing and diabetic cardiovascular autonomic neuropathy. The most frequent clinical condition in which alpha-lipoic acid has been studied was in the management of diabetic peripheral neuropathy in patients with type 1 as well type 2 diabetes. Considering that oxidative stress, a imbalance between pro and antioxidants with excessive production of reactive oxygen species, is a factor in the development of many diseases and that alpha-lipoic acid, a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues we wrote this article in order to make an up-to-date review of current thinking regarding alpha-lipoic acid and its use as an antioxidant drug therapy for a myriad of diseases that could have potential benefits from its use.

Experimental models of non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the Western world, and it persists at a high prevalence. NAFLD is characterised by the accumulation of triglycerides in the liver and includes a spectrum of histopathological findings, ranging from simple fatty liver through non-alcoholic steatohepatitis (NASH) to fibrosis and ultimately cirrhosis, which may progress to hepatocellular carcinoma. The pathogenesis of NAFLD is closely related to the metabolic syndrome and insulin resistance. Understanding the pathophysiology and treatment of NAFLD in humans has currently been limited by the lack of satisfactory animal models. The ideal animal model for NAFLD should reflect all aspects of the intricate etiopathogenesis of human NAFLD and the typical histological findings of its different stages. Within the past several years, great emphasis has been placed on the development of an appropriate model for human NASH. This paper reviews the widely used experimental models of NAFLD in rats. We discuss nutritional, genetic and combined models of NAFLD and their pros and cons. The choice of a suitable animal model for this disease while respecting its limitations may help to improve the understanding of its complex pathogenesis and to discover appropriate therapeutic strategies. Considering the legislative, ethical, economical and health factors of NAFLD, animal models are essential tools for the research of this disease.