leptin and 4-hydroxy-2-nonenal

The aim of this study was to investigate the effects of medium-chain triglycerides (MCTs) on chemically-induced hepatic carcinogenesis (HCC) in mice.. In a first set of experiments, mice were treated with diethylnitrosoamine intraperitoneally at two weeks of age. They were fed chow containing MCT or a normal chow diet and sacrificed after 28 weeks. Incidence of hepatic tumor was compared between the two groups. Expression of oxidative stress, and inflammatory cytokines and chemokines in liver tissues were examined. In a second set of experiments, the histopathological findings of the intraperitoneal adipose tissue were assessed, and expression of adipocytokines in the fat tissue was measured. In a third set of experiments, plasma β-hydroxybutyrate (HB) concentration was measured in both animals fed chow containing MCT and a normal chow diet. Mouse HCC cells were co-cultured with β-HB, and the numbers of tumor cells were counted at days 3 and 7.. In the first set of experiments, the tumor count observed in the control group was significantly blunted in the MCT group. Maximum tumor diameter also decreased in the MCT group compared to the control group. The expression of inflammatory cytokines and chemokines was significantly decreased by MCT. Furthermore, expression of 4-hydroxynonenal was lower in the MCT group compared to the control group. In the second set of experiments, hypertrophy of the adipocytes was suppressed, and the concentration of adiponectin and leptin in the adipose tissue decreased by MCT. In the third set of experiments, plasma β-HB concentration increased in the MCT group as expected. β-HB significantly inhibited the proliferation of HCC cells.. MCT administration markedly suppresses the incidence of chemically-induced HCC by inhibition of inflammation and increase of ketone bodies.

Topics: 3-Hydroxybutyric Acid; Adipocytes; Adipokines; Adiponectin; Adipose Tissue; Aldehydes; Animal Feed; Animals; Carcinogens; Carcinoma, Hepatocellular; Cell Count; Cell Proliferation; Chemokines; Cytokines; Diethylnitrosamine; Hypertrophy; Inflammation; Leptin; Liver; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred C3H; Oxidative Stress; Triglycerides

Insensitivity to the antiobesity hormone, leptin, has been suggested to be involved in the pathogenesis of obesity. However, the pathological mechanisms underlying the development of leptin resistance are not well-understood. This study aimed to examine the pathological mechanisms of leptin resistance in obesity. In the present study, we found that 4-hydroxy-2-nonenal (4-HNE), an aldehyde, may be involved in the development of leptin resistance. The SH-SY5Y-Ob-Rb human neuroblastoma cell line, transfected to express the Ob-Rb leptin receptor stably, was treated with 4-HNE, and leptin-induced signal transduction was analyzed. We found that 4-HNE dose- and time-dependently inhibited leptin-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation, a major antiobesity signal of leptin. On the other hand, 4-HNE did not affect tyrosine phosphorylation of broad cellular proteins, suggesting that the inhibitory effect may be selective to leptin signaling. Mechanistically, 4-HNE induced the eukaryotic initiation factor 2α-CCAAT/enhancer-binding protein homologous protein arm of endoplasmic reticulum stress signaling, which may be involved in the pathogenesis of leptin resistance. Overall, these results suggest that 4-HNE may partly affect endoplasmic reticulum stress-induced unfolded protein response signaling and may be involved in the pathogenesis of leptin resistance.

Topics: Aldehydes; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Endoplasmic Reticulum Stress; Humans; Leptin; Obesity; Receptors, Leptin

The prevalence of obesity is increasing worldwide. Oxidative stress plays an etiological role in a variety of obesity-related metabolic disorders. 4-hydroxynonenal (4-HNE) is the most abundant and reactive aldehydic product derived from the peroxidation of n-6 polyunsaturated fatty acids with diverse biological effects that are not well detailed. Obesity is associated with decreased plasma adiponectin concentrations and increased production of lipid peroxidation products, including 4-HNE, in adipose tissue. There may be some association between the level of adipokines and 4-HNE.. To analyze the associations between 4-HNE and classical adipokines, namely, adiponectin and leptin in a Chinese population, the plasma 4-HNE, adiponectin and leptin levels of 160 non-diabetic obese (NDO) patients and 160 healthy subjects were determined by ELISA, and their associations with adiposity, glucose, lipid profiles, insulin secretion and insulin sensitivity were studied.. Plasma 4-HNE levels were significantly increased in patients with NDO compared with healthy controls (p < 0.01). 4-HNE was negatively correlated with adiponectin and positively correlated with leptin. The plasma levels of 4-HNE were significantly correlated to several parameters involved in body mass index (BMI) and insulin resistance (IR). The 4-HNE levels were positively correlated with BMI and negatively correlated with insulin sensitivity.. We conclude that 4-HNE is associated with the secretion of adiponectin and leptin and is correlated with IR in NDO humans. These findings indicate a pro-inflammatory role of 4-HNE in NDO patients, which supports the potential role of 4-HNE in the development of obesity-related disorders.

Topics: Adipokines; Adiponectin; Adult; Aged; Aldehydes; Asian People; Biomarkers; China; Female; Humans; Insulin Resistance; Leptin; Male; Middle Aged; Obesity

Insulin resistance, oxidative stress, inflammation and innate immune system activation contribute to the development of non-alcoholic fatty liver disease (NAFLD) through steatosis and inflammation in the liver. The powerful antioxidant α-lipoic acid (ALA) has been shown to improve insulin sensitivity and suppress inflammatory responses. This study explores how ALA administration protects against NAFLD.. Otsuka Long-Evans Tokushima Fatty (OLETF) rats were divided into two groups (treated with 200 mg/kg/day of ALA or untreated) at 12 weeks of age and sacrificed at 28 weeks of age.. Serum levels of insulin, free fatty acids, total cholesterol, triglyceride, leptin, IL-6 and blood glucose were decreased in ALA-treated rats. Serum adiponectin levels were higher in ALA-treated rats. ALA treatment decreased the expression of sterol regulatory element binding protein-1 and acetyl CoA carboxylase, and increased glucose transporter-4 expression in the livers of OLETF rats. Expression of the antioxidant enzymes heme oxygenase-1 and Cu/Zn-superoxide dismutase was increased in the livers of ALA-treated rats. The lipid peroxidation marker 4-hydroxynonenal was decreased in the liver of ALA-treated rats. Proteins associated with innate immune activation (Toll-like receptor-4 and high-mobility group protein box-1) and inflammatory markers (vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and cyclooxygenase-2) were decreased in the livers of ALA-treated rats.. Chronic ALA supplementation prevents NAFLD through multiple mechanisms by reducing steatosis, oxidative stress, immune activation and inflammation in the liver.

Topics: Acetyl-CoA Carboxylase; Adiponectin; Aldehydes; Animals; Azo Compounds; Blood Glucose; Blotting, Western; Cholesterol; Cyclooxygenase 2; Fatty Acids; Fatty Liver; Fluorescent Antibody Technique; Gene Expression Regulation; Glucose Transporter Type 4; Immunity, Innate; Immunohistochemistry; Insulin; Intercellular Adhesion Molecule-1; Interleukin-6; Leptin; Lipid Peroxidation; Liver; Non-alcoholic Fatty Liver Disease; Rats; Rats, Inbred OLETF; Sterol Regulatory Element Binding Protein 1; Thioctic Acid; Toll-Like Receptor 4; Triglycerides; Vascular Cell Adhesion Molecule-1

Most people with diabetes develop severe complications of the autonomic nervous system; yet, the underlying causes of many diabetic-induced dysautonomias are poorly understood. Here we explore the idea that these dysautonomias results, in part, from a defect in synaptic transmission. To test this idea, we investigated cultured sympathetic neurons and show that hyperglycemia inactivates nAChRs through a mechanism involving an elevation in reactive oxygen species and an interaction with highly conserved cysteine residues located near the intracellular mouth of the nAChR channel. Consistent with this, we show that diabetic mice have depressed ganglionic transmission and reduced sympathetic reflexes, whereas diabetic mice expressing mutant postsynaptic nAChRs that lack the conserved cysteine residues on the alpha3 subunit have normal synaptic transmission in sympathetic ganglia and normal sympathetic reflexes. Our work suggests a new model for diabetic-induced dysautonomias and identifies ganglionic nAChRs as targets of hyperglycemia-induced downstream signals.

Topics: Acetylcholine; Adenoviridae; Age Factors; Aldehydes; Animals; Animals, Newborn; Body Temperature; Cells, Cultured; Cysteine; Diabetes Mellitus, Experimental; Disease Models, Animal; Enzyme Inhibitors; Excitatory Postsynaptic Potentials; Glucose; Guanidines; Heart Rate; Hypoglycemic Agents; Insulin; Leptin; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mutation; Oxidative Stress; Patch-Clamp Techniques; Reactive Oxygen Species; Receptors, Leptin; Receptors, Nicotinic; Sensory Receptor Cells; Superior Cervical Ganglion; Synaptic Transmission

Adipokines such as leptin and adiponectin are adipocyte-specific secretory proteins that play important roles in the metabolic regulation of body weight, insulin resistance and cardiovascular complications. The relationship between the malnutrition-inflammation complex syndrome and high levels of some adipokines in peritoneal dialysis (PD) patients is still unclear. An association between high body mass index (BMI) and improved survival in PD patients has also been proposed. The purpose of this study was to investigate the levels of plasma adipokines and inflammation and oxidative stress markers in overweight and normal weight PD patients.. Thirty PD patients (12 M, 18 F; mean age 57.3 ± 16.6 years) were examined and 23 healthy volunteers were included as a control group. The levels of high-sensitivity C-reactive protein (hsCRP), tumour necrosis factor-α, interleukin-6, leptin, the leptin receptor, adiponectin, malondialdehyde/4-hydroxynonenal, oxidized low-density lipoprotein, carbonyl groups and asymmetric dimethylarginine (ADMA) were measured in both groups. The nutritional status of each patient was determined by albumin levels, BMI, percentage of body fat (%F), lean body mass (LBM) and the Subjective Global Assessment (SGA) score. The adequacy of dialysis was estimated by weekly Kt/V measurements.. According to the seven-point SGA scores and the albumin levels, the nutrition status of 15 patients was good (6-7 points), while 15 patients were mildly malnourished (3-5 points). The concentrations of hsCRP, leptin and adiponectin were statistically higher in the PD group than in the control group (p < 0.05). Markers of oxidative stress and inflammation were also higher in the PD group. The adiponectin level was inversely correlated with %F and BMI (Spearman's R = -0.3, p ≤ 0.05) and positively correlated with hsCRP level (R = -0.4). The level of leptin was positively correlated with %F, BMI and LBM (R = 0.4, p ≤ 0.05). Patients with normal BMI values had lower leptin concentrations (50.2 vs 242.8 μg/l) and higher adiponectin levels (30.0 vs 20.3 μg/ml) than overweight patients. The statistical analysis indicated that there were no differences in oxidative stress, inflammation and ADMA concentration between the lean and overweight PD patients.. The nutritional status of lean and overweight patients was comparable. Signs of malnutrition were detected in both groups. The severity of chronic inflammation and oxidative stress were not related to BMI in PD patients.

Topics: Adiponectin; Adult; Aged; Aldehydes; Arginine; Biomarkers; Body Mass Index; Body Weight; C-Reactive Protein; Cardiovascular Diseases; Endothelium; Female; Humans; Inflammation; Interleukin-6; Leptin; Lipoproteins, LDL; Male; Malnutrition; Malondialdehyde; Middle Aged; Nutritional Status; Oxidative Stress; Peritoneal Dialysis; Risk Factors; Tumor Necrosis Factor-alpha

Recent studies suggest that adipose tissue hormone, leptin, is involved in the pathogenesis of arterial hypertension. However, the mechanism of hypertensive effect of leptin is incompletely understood. We investigated whether antioxidant treatment could prevent leptin-induced hypertension. Hyperleptinemia was induced in male Wistar rats by administration of exogenous leptin (0.25 mg/kg twice daily s.c. for 7 days) and separate groups were simultaneously treated with superoxide scavenger, tempol, or NAD(P)H oxidase inhibitor, apocynin (2 mM in the drinking water). After 7 days, systolic blood pressure was 20.6% higher in leptin-treated than in control animals. Both tempol and apocynin prevented leptin-induced increase in blood pressure. Plasma concentration and urinary excretion of 8-isoprostanes increased in leptin-treated rats by 66.9% and 67.7%, respectively. The level of lipid peroxidation products, malonyldialdehyde + 4-hydroxyalkenals (MDA+4-HNE), was 60.3% higher in the renal cortex and 48.1% higher in the renal medulla of leptin-treated animals. Aconitase activity decreased in these regions of the kidney following leptin administration by 44.8% and 45.1%, respectively. Leptin increased nitrotyrosine concentration in plasma and renal tissue. Urinary excretion of nitric oxide metabolites (NO(x)) was 57.4% lower and cyclic GMP excretion was 32.0% lower in leptin-treated than in control group. Leptin decreased absolute and fractional sodium excretion by 44.5% and 44.7%, respectively. Co-treatment with either tempol or apocynin normalized 8-isoprostanes, MDA+4-HNE, aconitase activity, nitrotyrosine, as well as urinary excretion of NO(x), cGMP and sodium in rats receiving leptin. These results indicate that oxidative stress-induced NO deficiency is involved in the pathogenesis of leptin-induced hypertension.

Topics: Acetophenones; Aconitate Hydratase; Aldehydes; Animals; Antioxidants; Blood Pressure; Body Weight; Creatine; Cyclic GMP; Cyclic N-Oxides; Drinking; Eating; Hypertension; Isoprostanes; Kidney; Leptin; Male; Malondialdehyde; Natriuresis; Nitric Oxide; Rats; Rats, Wistar; Reactive Nitrogen Species; Sodium; Spin Labels; Tyrosine