astaxanthine and Insulin-Resistance

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver disorders worldwide. It is associated with clinical states such as obesity, insulin resistance, and type 2 diabetes, and covers a wide range of liver changes, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. Metabolic disorders, such as lipid accumulation, insulin resistance, and inflammation, have been implicated in the pathogenesis of NAFLD, but the underlying mechanisms, including those that drive disease progression, are not fully understood. Both innate and recruited immune cells mediate the development of insulin resistance and NASH. Therefore, modifying the polarization of resident and recruited macrophage/Kupffer cells is expected to lead to new therapeutic strategies in NAFLD. Oxidative stress is also pivotal for the progression of NASH, which has generated interest in carotenoids as potent micronutrient antioxidants in the treatment of NAFLD. In addition to their antioxidative function, carotenoids regulate macrophage/Kupffer cell polarization and thereby prevent NASH progression. In this review, we summarize the molecular mechanisms involved in the pathogenesis of NAFLD, including macrophage/Kupffer cell polarization, and disturbed hepatic function in NAFLD. We also discuss dietary antioxidants, such as β-cryptoxanthin and astaxanthin, that may be effective in the prevention or treatment of NAFLD.

Topics: Antioxidants; Carotenoids; Cryptoxanthins; Humans; Insulin Resistance; Liver; Macrophages; Non-alcoholic Fatty Liver Disease; Oxidative Stress; Xanthophylls

Astaxanthin suppressed obesity in rats fed with high-fat diet (HFD) via the restriction of adipose tissue build-out, therefore, improving insulin sensitivity and inflammation. Metformin reduces insulin resistance and may reduce weight.. Investigation of the effects of astaxanthin and metformin in obesity prompted by a high-fat diet.. The present article investigates the effects of astaxanthin and metformin in obesity prompted by a high-fat diet in rats through measuring miRNA222 and 378.. The rats were classified into four classes containing ten albino rats each: Group I (Normal group): nourished with ordinary diet for 8weeks. Group II (Control positive): nourished with a high-fat diet for 8 weeks. Group III: nourished with astaxanthin (50mg/kg)(1/40 LD50) orally plus a high-fat diet for 8weeks. Group IV: nourished with metformin (500mg/kg) orally plus a high-fat diet for 8 weeks.. Leptin, adiponectin, calprotectin and interleukin 6 (IL-6) were assessed by rat-specific ELISA kits. Tumor necrosis factor-alpha (TNF-α), miRNA222 and miRNA378 expressions were quantified by quantitative real-time PCR.. Astaxanthin and metformin have anti-obesity and antioxidant actions and significantly decreased the weight of the body, glucose, insulin, triglycerides, total cholesterol, triglycerides and leptin, as well as plasma calprotectin & IL-6 and increased HDL-C and adiponectin. The liver TNF-α gene expression, adipose tissue miRNA222 and miRNA378 expression were decreased compared to HFD control rats.. Astaxanthin has regulated the aberrant expression of miRNA222 and 378 that may be related to hyperlipidemia and insulin resistance. Accordingly, astaxanthin deserves a clinical trial in the future due to its effects on miRNAs involved in obesity.

Topics: Adiponectin; Adipose Tissue; Animals; Diet, High-Fat; Insulin; Insulin Resistance; Leukocyte L1 Antigen Complex; Obesity; Rats; Xanthophylls

Recently, obesity-induced insulin resistance, type 2 diabetes, and cardiovascular disease have become major social problems. We have previously shown that Astaxanthin (AX), which is a natural antioxidant, significantly ameliorates obesity-induced glucose intolerance and insulin resistance. It is well known that AX is a strong lipophilic antioxidant and has been shown to be beneficial for acute inflammation. However, the actual effects of AX on chronic inflammation in adipose tissue (AT) remain unclear. To observe the effects of AX on AT functions in obese mice, we fed six-week-old male C57BL/6J on high-fat-diet (HFD) supplemented with or without 0.02% of AX for 24 weeks. We determined the effect of AX at 10 and 24 weeks of HFD with or without AX on various parameters including insulin sensitivity, glucose tolerance, inflammation, and mitochondrial function in AT. We found that AX significantly reduced oxidative stress and macrophage infiltration into AT, as well as maintaining healthy AT function. Furthermore, AX prevented pathological AT remodeling probably caused by hypoxia in AT. Collectively, AX treatment exerted anti-inflammatory effects via its antioxidant activity in AT, maintained the vascular structure of AT and preserved the stem cells and progenitor's niche, and enhanced anti-inflammatory hypoxia induction factor-2α-dominant hypoxic response. Through these mechanisms of action, it prevented the pathological remodeling of AT and maintained its integrity.

Topics: Adipose Tissue; Animals; Anti-Inflammatory Agents; Antioxidants; Cytokines; Dietary Supplements; Glucose; Inflammation; Inflammation Mediators; Insulin Resistance; Macrophages; Male; Mice, Inbred C57BL; Mitochondria; Oxidative Stress; Xanthophylls

Type 2 diabetes mellitus (T2DM), which is characterized by insulin resistance and relative insulin insufficiency, has become the most common chronic metabolic disease threatening global health. The preferred therapies for T2DM include lifestyle interventions and the use of anti-diabetic drugs. However, considering their adverse reactions, it is important to find a low-toxicity and effective functional food or drug for diabetes prevention and treatment. Astaxanthin is a potent antioxidant carotenoid found in marine organisms has been reported to prevent diet-induced insulin resistance and hepatic steatosis. To investigate the anti-diabetic effects of astaxanthin, male Wistar rats were fed a high-energy diet for 4 weeks, followed by a low dose streptozotocin (STZ) injection to induce the diabetes model, and the rats were then fed an astaxanthin-containing diet for another 3 weeks. Astaxanthin significantly decreased blood glucose and total cholesterol (TC) levels, and increased blood levels of high density lipoprotein cholesterol (HDL-C) in STZ-induced diabetic rats in a dose dependent manner. These results were associated with increased expression of insulin sensitivity related genes (adiponectin, adipoR1, and adipoR2) in vivo, thereby attenuating STZ-induced diabetes. In addition, we also compared the anti-diabetic effects of astaxanthin and monacolin K, which has been reported to downregulate hyperlipidemia and hyperglycemia. The results revealed that astaxanthin and monacolin K showed similar anti-diabetic effects in STZ-induced diabetic rats. Therefore, astaxanthin may be developed as an anti-diabetic agent in the future.

Topics: Animals; Blood Glucose; Cholesterol; Diabetes Mellitus, Experimental; Hypoglycemic Agents; Insulin Resistance; Male; Rats; Rats, Wistar; Xanthophylls

Skeletal muscle is mainly responsible for insulin-stimulated glucose disposal. Dysfunction in skeletal muscle metabolism especially during obesity contributes to the insulin resistance. Astaxanthin (AX), a natural antioxidant, has been shown to ameliorate hepatic insulin resistance in obese mice. However, its effects in skeletal muscle are poorly understood. The current study aimed to investigate the molecular target of AX in ameliorating skeletal muscle insulin resistance.. We fed 6-week-old male C57BL/6J mice with normal chow (NC) or NC supplemented with AX (NC+AX) and high-fat-diet (HFD) or HFD supplemented with AX for 24 weeks. We determined the effect of AX on various parameters including insulin sensitivity, glucose uptake, inflammation, kinase signaling, gene expression, and mitochondrial function in muscle. We also determined energy metabolism in intact C2C12 cells treated with AX using the Seahorse XFe96 Extracellular Flux Analyzer and assessed the effect of AX on mitochondrial oxidative phosphorylation and mitochondrial biogenesis.. AX-treated HFD mice showed improved metabolic status with significant reduction in blood glucose, serum total triglycerides, and cholesterol (p< 0.05). AX-treated HFD mice also showed improved glucose metabolism by enhancing glucose incorporation into peripheral target tissues, such as the skeletal muscle, rather than by suppressing gluconeogenesis in the liver as shown by hyperinsulinemic-euglycemic clamp study. AX activated AMPK in the skeletal muscle of the HFD mice and upregulated the expressions of transcriptional factors and coactivator, thereby inducing mitochondrial remodeling, including increased mitochondrial oxidative phosphorylation component and free fatty acid metabolism. We also assessed the effects of AX on mitochondrial biogenesis in the siRNA-mediated AMPK-depleted C2C12 cells and showed that the effect of AX was lost in the genetically AMPK-depleted C2C12 cells. Collectively, AX treatment (i) significantly ameliorated insulin resistance and glucose intolerance through regulation of AMPK activation in the muscle, (ii) stimulated mitochondrial biogenesis in the muscle, (iii) enhanced exercise tolerance and exercise-induced fatty acid metabolism, and (iv) exerted antiinflammatory effects via its antioxidant activity in adipose tissue.. We concluded that AX treatment stimulated mitochondrial biogenesis and significantly ameliorated insulin resistance through activation of AMPK pathway in the skeletal muscle.

Topics: AMP-Activated Protein Kinases; Animals; Fibrinolytic Agents; Humans; Insulin Resistance; Male; Mice; Mitochondria, Muscle; Organelle Biogenesis; Xanthophylls

Astaxanthin (AST) is a carotenoid with therapeutic values on hyperglycemia and diabetic complications. The mechanisms of action of AST remain incompletely understood. p70 S6 kinase 1 (S6K1) is a serine/threonine kinase that phosphorylates insulin receptor substrate 1 (IRS-1)

Topics: 3T3-L1 Cells; Adipocytes; Animals; Cell Line; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Mice; Molecular Targeted Therapy; Muscle Fibers, Skeletal; Phosphorylation; Rats; Receptor, Insulin; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Xanthophylls

With the constant failure of the clinical trials continuous exploration of a therapeutic target against Alzheimer's disease (AD) is the utmost need. Numerous studies have supported the hypothesis that central insulin resistance plays a significant role in AD. Serine phosphorylation of Insulin Receptor Substarte-1 (IRS-1) has been found to be a contributing factor in neuronal insulin resistance. Astaxanthin (ASX) is xanthophyll carotenoid which has previously demonstrated significant antidiabetic and neuroprotective actions. In the present study, AD was induced by i.c.v administration of Amyloid-β (1-42) peptides in Wistar rats. After 7 days of recovery, rats were treated with 0.5 mg/kg and 1 mg/kg of ASX orally for 28 days. Behavioral analysis was done in the last week of our experimental study. On the 36th day, rats were sacrificed and their hippocampus were separated from the whole brain, then homogenized and stored for biochemical estimations. ASX significantly and dose-dependently reversed the cognitive and memory impairment, assessed by Morris water maze test and Novel object Recognition test, Aβ (1-42) peptides infused Wistar rats. ASX also significantly attenuated soluble Aβ (1-42) level, IRS-S307 activity, GSK-3β activity, TNF-α level, AChE level, nitrite level and oxidative stress in the hippocampus. Histopathological evaluation, done through H&E and Congo red staining, also demonstrated neuroprotective and anti-amyloidogenic effects of ASX in hippocampus. Our study concludes preventive action of Astaxanthin against hippocampal insulin resistance and Alzheimer's disease complications, supporting potential role of hippocampal insulin resistance targeting against AD.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Hippocampus; Injections, Intraventricular; Insulin Resistance; Maze Learning; Neuroprotective Agents; Peptide Fragments; Random Allocation; Rats; Rats, Wistar; Xanthophylls

Diet-induced obesity, insulin resistance, impaired glucose tolerance, chronic inflammation, and oxidative stress represent the main features of type 2 diabetes mellitus. The present study was conducted to examine the efficacy and mechanisms of shrimp oil on glucose homeostasis in obese rats. Male CD rats fed a high-fat diet (52 kcal% fat) and 20% fructose drinking water were divided into 4 groups and treated with the dietary replacement of 0%, 10%, 15%, or 20% of lard with shrimp oil for 10 weeks. Age-matched rats fed a low-fat diet (10 kcal% fat) were used as the normal control. Rats on the high-fat diet showed impaired (p < 0.05) glucose tolerance and insulin resistance compared with rats fed the low-fat diet. Shrimp oil improved (p < 0.05) oral glucose tolerance, insulin response, and homeostatic model assessment-estimated insulin resistance index; decreased serum insulin, leptin, hemoglobin A1c, and free fatty acids; and increased adiponectin. Shrimp oil also increased (p < 0.05) antioxidant capacity and reduced oxidative stress and chronic inflammation. The results demonstrated that shrimp oil dose-dependently improved glycemic control in obese rats through multiple mechanisms.

Topics: Adiponectin; Animals; Anostraca; Biomarkers; Blood Glucose; Diet, High-Fat; Dietary Fats; Fatty Acids, Nonesterified; Glucose Intolerance; Glycated Hemoglobin; Insulin; Insulin Resistance; Leptin; Male; Obesity; Oils; Oxidative Stress; Rats; Shellfish; Vitamin A; Vitamin E; Xanthophylls

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Topics: Animals; Computational Biology; Diet; Insulin Resistance; Mice; Non-alcoholic Fatty Liver Disease; Vitamin E; Xanthophylls

Hepatic insulin resistance and nonalcoholic steatohepatitis (NASH) could be caused by excessive hepatic lipid accumulation and peroxidation. Vitamin E has become a standard treatment for NASH. However, astaxanthin, an antioxidant carotenoid, inhibits lipid peroxidation more potently than vitamin E. Here, we compared the effects of astaxanthin and vitamin E in NASH. We first demonstrated that astaxanthin ameliorated hepatic steatosis in both genetically (ob/ob) and high-fat-diet-induced obese mice. In a lipotoxic model of NASH: mice fed a high-cholesterol and high-fat diet, astaxanthin alleviated excessive hepatic lipid accumulation and peroxidation, increased the proportion of M1-type macrophages/Kupffer cells, and activated stellate cells to improve hepatic inflammation and fibrosis. Moreover, astaxanthin caused an M2-dominant shift in macrophages/Kupffer cells and a subsequent reduction in CD4(+) and CD8(+) T cell recruitment in the liver, which contributed to improved insulin resistance and hepatic inflammation. Importantly, astaxanthin reversed insulin resistance, as well as hepatic inflammation and fibrosis, in pre-existing NASH. Overall, astaxanthin was more effective at both preventing and treating NASH compared with vitamin E in mice. Furthermore, astaxanthin improved hepatic steatosis and tended to ameliorate the progression of NASH in biopsy-proven human subjects. These results suggest that astaxanthin might be a novel and promising treatment for NASH.

Topics: Animals; Antioxidants; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Diet, High-Fat; Disease Models, Animal; Female; Glucose Metabolism Disorders; Humans; Insulin Resistance; Kupffer Cells; Lipid Peroxidation; Liver; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Non-alcoholic Fatty Liver Disease; Sterol Regulatory Element Binding Protein 1; Vitamin E; Xanthophylls

Because oxidative stress promotes insulin resistance in obesity and type 2 diabetes, it is crucial to find effective antioxidant for the purpose of decreasing this threat. In this study, we explored the effect of astaxanthin, a carotenoid antioxidant, on insulin signaling and investigated whether astaxanthin improves cytokine- and free fatty acid-induced insulin resistance in vitro. We examined the effect of astaxanthin on insulin-stimulated glucose transporter 4 (GLUT4) translocation, glucose uptake, and insulin signaling in cultured rat L6 muscle cells using plasma membrane lawn assay, 2-deoxyglucose uptake, and Western blot analysis. Next, we examined the effect of astaxanthin on TNFα- and palmitate-induced insulin resistance. The amount of reactive oxygen species generated by TNFα or palmitate with or without astaxanthin was evaluated by dichlorofluorescein staining. We also compared the effect of astaxanthin on insulin signaling with that of other antioxidants, α-lipoic acid and α-tocopherol. We observed astaxanthin enhanced insulin-stimulated GLUT4 translocation and glucose uptake, which was associated with an increase in insulin receptor substrate-1 tyrosine and Akt phosphorylation and a decrease in c-Jun N-terminal kinase (JNK) and insulin receptor substrate-1 serine 307 phosphorylation. Furthermore, astaxanthin restored TNFα- and palmitate-induced decreases in insulin-stimulated GLUT4 translocation or glucose uptake with a concomitant decrease in reactive oxygen species generation. α-Lipoic acid enhanced Akt phosphorylation and decreased ERK and JNK phosphorylation, whereas α-tocopherol enhanced ERK and JNK phosphorylation but had little effect on Akt phosphorylation. Collectively these findings indicate astaxanthin is a very effective antioxidant for ameliorating insulin resistance by protecting cells from oxidative stress generated by various stimuli including TNFα and palmitate.

Topics: alpha-Tocopherol; Animals; Antioxidants; Blotting, Western; Cell Line; Deoxyglucose; Glucose Transporter Type 4; Hypoglycemic Agents; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; JNK Mitogen-Activated Protein Kinases; Myoblasts; Phosphorylation; Protein Transport; Proto-Oncogene Proteins c-akt; Rats; Reactive Oxygen Species; Signal Transduction; Thioctic Acid; Tumor Necrosis Factor-alpha; Xanthophylls

Astaxanthin (ASX), a xanthophyll carotenoid from the marine algae Hematococcus pluvialis, has anti-obesity and insulin-sensitivity effects. The specific molecular mechanisms of its actions are not yet established. The present study was designed to investigate the mechanisms underlying the insulin sensitivity effects of ASX in a non-genetic insulin resistant animal model. A group of male Swiss albino mice was divided into two and fed either a starch-based control diet or a high fat-high fructose diet (HFFD). Fifteen days later, mice in each dietary group were divided into two and were treated with either ASX (6 mg kg(-1) per day) in olive oil or olive oil alone. At the end of 60 days, glucose, insulin and pro-inflammatory cytokines in plasma, lipids and oxidative stress markers in skeletal muscle and adipose tissue were assessed. Further, post-receptor insulin signaling events in skeletal muscle were analyzed. Increased body weight, hyperglycemia, hyperinsulinemia and increased plasma levels of tumor necrosis factor-α and interleukin-6 observed in HFFD-fed mice were significantly improved by ASX addition. ASX treatment also reduced lipid levels and oxidative stress in skeletal muscle and adipose tissue. ASX improved insulin signaling by enhancing the autophosphorylation of insulin receptor-β (IR-β), IRS-1 associated PI3-kinase step, phospho-Akt/Akt ratio and GLUT-4 translocation in skeletal muscle. This study demonstrates for the first time that chronic ASX administration improves insulin sensitivity by activating the post-receptor insulin signaling and by reducing oxidative stress, lipid accumulation and proinflammatory cytokines in obese mice.

Topics: Adipose Tissue; Animals; Anti-Obesity Agents; Blood Glucose; Cytokines; Diet; Diet, High-Fat; Fructose; Glucose Transporter Type 4; Hyperglycemia; Hyperinsulinism; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Interleukin-6; Lipid Metabolism; Lipids; Male; Mice; Mice, Obese; Muscle, Skeletal; Oxidative Stress; Phosphatidylinositol 3-Kinases; Phosphorylation; Receptor, Insulin; Signal Transduction; Tumor Necrosis Factor-alpha; Volvocida; Xanthophylls

This study investigates the effects of astaxanthin (ASX) on insulin signaling and glucose metabolism in the liver of mice fed a high fat and high fructose diet (HFFD). Adult male Mus musculus mice of body mass 25-30 g were fed either normal chow or the HFFD. After 15 days, mice in each group were subdivided among 2 smaller groups and treated with ASX (2 mg·(kg body mass)⁻¹) in olive oil for 45 days. At the end of 60 days, HFFD-fed mice displayed insulin resistance while ASX-treated HFFD animals showed marked improvement in insulin sensitivity parameters. ASX treatment normalized the activities of hexokinase, pyruvate kinase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glycogen phosphorylase, and increased glycogen reserves in the liver. Liver tissue from ASX-treated HFFD-fed animals showed increased tyrosine phosphorylation and decreased serine phosphorylation of insulin receptor substrates (IRS)-1 and -2. ASX increased IRS 1/2 and phosphatidylinositol 3-kinase (PI3K) association and serine phosphorylation of Akt. In addition, ASX decreased HFFD-induced serine kinases (c-jun N-terminal kinase-1 and extracellular signal-regulated kinase-1). The results suggest that ASX treatment promotes the IRS-PI3K-Akt pathway of insulin signaling by decreasing serine phosphorylation of IRS proteins, and improves glucose metabolism by modulating metabolic enzymes.

Topics: Animals; Antioxidants; Dietary Supplements; Hyperglycemia; Hypoglycemic Agents; Insulin Receptor Substrate Proteins; Insulin Resistance; Liver; Liver Glycogen; Male; Mice; Phosphatidylinositol 3-Kinase; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Random Allocation; Serine; Signal Transduction; Tyrosine; Xanthophylls

The present investigation in Sprague-Dawley rats (SD) was designed to examine effects of astaxanthin (Asta) at different doses on elevated blood pressure (BP) and glucose-insulin perturbations produced by heavy sucrose ingestion. We also examined effects of Asta on BP during restraint stress. SD were divided into six groups each containing eight rats. All SD ate a basic diet of ground regular rat chow with sucrose added at 30% w/w. The Control group received only the basic diet containing added sucrose, while the other five groups each received the same diet with added test material: captopril, (30 mg/Kg), pioglitazone (15.0 mg/Kg), low Asta (25 mg/Kg), medium Asta (50 mg/kg) or high Asta (100 mg/Kg). Many tests were carried out to examine the mechanisms behind the effects of Asta on BP (serum ACE activity, losartan challenge, and LNAME challenge) and the glucose-insulin system (glucose tolerance, HOMA measurement, and insulin challenge). In SD, a relatively low dose of Asta decreased SBP, but produced no major changes in the glucose-insulin system simulating results from a previous study using Zucker Fatty Rats. Increasing the dose of Asta resulted in both a lowering of elevated systolic BP and enhanced insulin sensitivity determined by many different estimations. BP lowering was consistent with changes in the renin-angiotensin (RAS) and nitric oxide (NO) systems. At the examined doses of each, captopril lowered BP in SD without influencing glucose-insulin metabolism, whereas pioglitazone favorably affected glucose-insulin metabolism while showing essentially no effects on BP. Accordingly, Asta beneficially affects both sucrose-induced elevations of BP and insulin resistance at relatively high doses in SD. Also, Asta at higher doses lessens restraint stress, whereas, captopril and pioglitazone did not at the doses examined, even though they influenced the BP and glucose-insulin systems respectively.

Topics: Animals; Blood Pressure; Body Weight; Dose-Response Relationship, Drug; Drinking Behavior; Feeding Behavior; Glucose Tolerance Test; Insulin Resistance; Male; Rats; Rats, Sprague-Dawley; Xanthophylls

Glucose and lipid metabolic parameters play crucial roles in metabolic syndrome and its major feature of insulin resistance. This study was designed to investigate whether dietary astaxanthin oil (ASX-O) has potential effects on metabolic syndrome features in an SHR/NDmcr-cp (cp/cp) rat model. Oral administration of ASX (50 mg/kg/day) for 22 weeks induced a significant reduction in arterial blood pressure in SHRcp. It also significantly reduced the fasting blood glucose level, homeostasis index of insulin resistance (HOMA-IR), and improved insulin sensitivity. The results also showed an improved adiponectin level, a significant increase in high-density lipoprotein cholesterol, a significant decrease in plasma levels of triglycerides, and non-esterified fatty acids. Additionally, ASX showed significant effects on the white adipose tissue by decreasing the size of the fat cells. These results suggest that ASX ameliorates insulin resistance by mechanisms involving the increase of glucose uptake, and by modulating the level of circulating lipid metabolites and adiponectin.

Topics: Adiponectin; Adipose Tissue; Administration, Oral; Animals; Blood Cell Count; Blood Glucose; Blood Pressure; Body Weight; Cell Size; Heart Rate; Hypertension; Insulin; Insulin Resistance; Lipid Metabolism; Male; Metabolic Syndrome; Rats; Rats, Inbred SHR; Rats, Wistar; Xanthophylls