thromboxane-b2 and Obesity

STUDY OBJECTIVE: Aspirin (ASA) has demonstrated inconsistent results in primary prevention of cardiovascular disease (CVD). Guidelines are also inconsistent in the recommendation of routine ASA use for primary prevention of CVD, but advocate dosing as a "one-size-fits-all" approach.. An intention-to-treat, double-blind, randomized, controlled, clinical trial comparing three treatment arms of ASA 81, 325, and 500 mg daily dosed for 14 days were evenly randomized across the dosing categories to measure the impact of dosing by body mass index (BMI) (20-24.9, 25-29.9, ≥30 kg/m. University Ambulatory Clinic.. Healthy volunteers defined as individuals who were medication free without acute or chronic significant health problems.. Change in ASA reactivity unit (ARU), salicylate levels, and thromboxane B2 (TxB2) levels were measured across BMI dosing categories and time. MAIN RESULTS: Fifty-four participants with a mean (±SD) age of 34.4 ± 10.9 years (M:F; 23:31) completed the study. Baseline ARU and TxB2 levels were not significantly different between obese and non-obese individuals. BMI was not a predictor of platelet inhibition. There was no interaction between gender and platelet activation at baseline or following ASA treatment. ASA 81 mg was associated with a lower ARU response (approximate 50% lower response) than either the 325-mg or the 500-mg doses of ASA. TxB2 and salicylate levels exhibited lower trends at 81 mg compared with higher doses.. In healthy male and female participants administered ASA for 14 days, obesity is not associated with increased basal platelet activation or ASA resistance. ASA 81 mg was significantly less effective in reducing platelet aggregation compared with ASA 325 and 500 mg, independent of BMI.

Topics: Adult; Aspirin; Body Mass Index; Cardiovascular Diseases; Female; Healthy Volunteers; Humans; Male; Middle Aged; Obesity; Platelet Aggregation Inhibitors; Prospective Studies; Thromboxane B2; Young Adult

Circulating pentraxin 3 (PTX3), the main regulator of the inflammatory response, rapidly increases following cardiovascular events, and low PTX3 is associated with high body mass index.. We conducted a 12-month longitudinal study, to test the hypothesis that laparoscopic adjustable gastric banding (LAGB)-induced weight loss was associated with changes in platelet activation markers and PTX3. Twelve obese patients, scheduled to undergo LAGB, were enrolled at the University Obesity Center. Urinary 11-dehydro-thromboxane (Tx)B2excretion rate was measured on radioimmunoassay, and PTX3 and CD40L were determined on immunoassay. Plasma PTX3 increased by 178.8 and 214.9% (P<0.0001), respectively, 6 and 12 months after LAGB. High-sensitivity CRP decreased by 24 and 29.7% (P<0.0001), whereas CD40L decreased by 64.3 and 58.6% (P=0.002), respectively. Urinary 11-dehydro-TxB2decreased from 1,443 to 715 and 564 pg/mg creatinine, respectively 6 months and 12 months after LAGB (P<0.0001). PTX3 was inversely related to platelet activation markers, 11-dehydro-TxB2and CD40L. Moreover, multiple regression analysis on pooled data showed that plasma PTX3 was an independent predictor of urinary 11-dehydro-TxB2.. There is an association between inflammation, platelet activation and metabolic dysfunction in obesity, and PTX3 is a key player within these circuits.

Topics: Adult; C-Reactive Protein; CD40 Ligand; Female; Follow-Up Studies; Gastric Bypass; Humans; Male; Middle Aged; Obesity; Platelet Activation; Serum Amyloid P-Component; Thromboxane B2

Low-dose aspirin prevents platelet aggregation by suppressing thromboxane A2 (TXA2 ) synthesis. However, in some individuals TXA2 suppression by aspirin is impaired, indicating suboptimal inhibition of platelet cyclooxygenase 1 (COX-1) by aspirin. Because patients with systemic lupus erythematosus (SLE) have increased risk of thrombotic events, many receive aspirin; however, the efficacy of aspirin in SLE has not been determined. We examined the hypothesis that aspirin response is impaired in SLE.. We assessed the effect of aspirin by measuring concentrations of the stable metabolite of TXA2 , serum thromboxane B2 (sTXB2 ), before and after treatment with daily aspirin (81 mg) for 7 days in 34 patients with SLE and 36 control subjects. The inability to suppress sTXB2 synthesis to <10 ng/ml represents suboptimal inhibition of platelet COX-1 by aspirin.. Aspirin almost completely suppressed sTXB2 in control subjects to median 1.5 ng/ml (interquartile range [IQR] 0.8-2.7) but had less effect in patients with SLE (median 3.1 ng/ml [IQR 2.2-5.3]) (P = 0.002). A suboptimal effect of aspirin was present in 15% (5 of 34) of the patients with SLE but not in control subjects (0 of 36) (P = 0.023). Incomplete responders were more likely to have metabolic syndrome (P = 0.048), obesity (P = 0.048), and higher concentrations of C-reactive protein (CRP) (P = 0.018).. The pharmacologic effect of aspirin is suboptimal in 15% of patients with SLE but in none of the control subjects, and the suboptimal response was associated with metabolic syndrome, obesity, and higher CRP concentrations.

Topics: Adult; Aspirin; Biomarkers; Blood Platelets; C-Reactive Protein; Chi-Square Distribution; Cyclooxygenase 1; Cyclooxygenase Inhibitors; Female; Humans; Lupus Erythematosus, Systemic; Male; Metabolic Syndrome; Middle Aged; Obesity; Prospective Studies; Thromboxane B2; Time Factors; Treatment Outcome

Walnut consumption produces beneficial cardiovascular effects. The aim of the present study is to compare the effects of meat enriched in walnut paste (WM) and low-fat meat (LM) consumptions on platelet aggregation, plasma thromboxane A2 (TXA2, measured as TXB2), prostacyclin I2 (PGI2, as 6-keto-PGF1alpha) and the thrombogenic ratio (TXB2/6-keto-PGF1alpha) in volunteers at high CVD risk. Twenty-two adults were placed on a random, non-blinded crossover study involving two test periods (five portions WM/week for 5 week; five portions LM/week for 5 week) separated by a 4- to 6-week washout period. The participants were asked to complete a diet record throughout the study. Platelet aggregation, plasma TXB2, 6-keto-PGF1alpha production and the TXB2/6-keto-PGF1alpha ratio were determined at baseline and at weeks 3 and 5 for the two dietary periods. The WM diet contains a lower SFA content, a higher concentration of PUFA and a more favourable n-6/n-3 ratio than the LM diet. Significant time x treatment interactions were observed for TXB2 (P = 0.048) and the TXB2/6-keto-PGF1alpha ratio (P = 0.028). The WM diet significantly increased the level of 6-keto-PGF1alpha (P = 0.037) and decreased the TXB2/6-keto-PGF1alpha ratio (P = 0.048). At week 5, significant differences (P < 0.05) between treatments were found for maximum aggregation rate, TXB2 values and the TXB2/6-keto-PGF1alpha ratio. The effects on TXB2 and the TXB2/6-keto-PGF1alpha ratio were time-course dependent (P = 0.019 and 0.011, respectively). The WM and LM diets reduced TXB2 levels most (P = 0.050) in obese individuals, while the TXB2/6-keto-PGF1alpha ratio decreased most (P = 0.066) in volunteers whose serum cholesterol levels were > or = 2200 mg/l. The WM diet should be considered a functional meat because it improves the thrombogenic status mainly in individuals with high-cholesterol levels or high BMI.

Topics: 6-Ketoprostaglandin F1 alpha; Analysis of Variance; Animals; Biomarkers; Body Mass Index; Cardiovascular Diseases; Cholesterol; Cross-Over Studies; Diet; Female; Humans; Juglans; Male; Meat; Middle Aged; Obesity; Phytotherapy; Platelet Aggregation; Risk; Smoking; Thromboxane A2; Thromboxane B2

Conjugated linoleic acid (CLA) has been shown in experimental studies to have chemoprotective properties, and may decrease the deposition of body fat. CLA is prone to oxidation, and it has been suggested that increased lipid oxidation may contribute to the anti-tumorigenic effects of this agent. The present study investigates the urinary levels of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)), a major isoprostane, and of 15-oxo-dihydro-PGF(2alpha), a major metabolite of PGF(2alpha), as indicators of non-enzymic and enzymic arachidonic acid oxidation respectively after dietary supplementation with CLA in middle-aged men (mean age 53 years) with abdominal obesity for 1 month in a randomized controlled trial. Significant increases in the levels of both 8-iso-PGF(2alpha) and 15-oxo-dihydro-PGF(2alpha) in urine (P<0. 0001 and P=0.0013 respectively) were observed after 1 month of daily CLA intake (4.2 g/day) as compared with the control group. The lipid peroxidation parameters had returned to their basal levels at 2 weeks after the cessation of CLA intake, and remained at the same levels for a further 2 weeks until the end of the study. CLA had no effect on serum alpha-tocopherol and gamma-tocopherol levels, or on the urinary levels of 2,3-dinor-thromboxane B(2). Thus CLA may induce both non-enzymic and enzymic lipid peroxidation in vivo in middle-aged men with abdominal obesity, without any side effects. The consequences of the increased lipid peroxidation after CLA supplementation are unknown.

Topics: Adult; Aged; Double-Blind Method; Humans; Linoleic Acids; Lipid Peroxidation; Male; Middle Aged; Obesity; Prostaglandins F; Thromboxane B2; Vitamin E

Recent data suggest a decreased clinical efficacy of low-dose aspirin in patients weighing ≥70 kg. We therefore investigated the impact of body weight and class 1 obesity on thromboxane generation and platelet reactivity to arachidonic acid (AA) in 316 patients on dual antiplatelet therapy following angioplasty and stenting.. Platelet surface expression of P-selectin and activated glycoprotein (GP) IIb/IIIa in response to AA were determined by flow cytometry as sensitive markers of platelet activation. Urinary 11-dehydro-thromboxane B2 (11-dehydro-TXB2) and serum TXB2 were measured by commercially-available immunoassays. On-treatment residual AA-inducible platelet aggregation was assessed by light transmission aggregometry (LTA), the VerifyNow aspirin assay and multiple electrode aggregometry (MEA).. Class 1 obesity was independently associated with increased platelet surface expression of P-selectin and activated GPIIb/IIIa, but not with urinary 11-dehydro-TXB2, serum TXB2, and on-treatment platelet aggregation by all assays. Of all measured parameters, only MEA showed a positive albeit very weak correlation with body weight (r = 0.13, p = 0.02). Furthermore, the results of all tests did not differ significantly between patients without and with a body weight ≥ 70 kg. After adjustment for age and diabetes by multivariate logistic regression analysis, the frequency of high-on treatment residual TXB2 generation and high on-treatment residual AA-inducible platelet reactivity (HRTG/HRPR) did not differ significantly between obese and non-obese patients.. Class 1 obesity is associated with enhanced platelet activation in response to AA in patients on dual antiplatelet therapy. This seems to be independent of cyclooxygenase-1 inhibition and does not translate into HRTG/HRPR.

Topics: Aged; Angioplasty; Aspirin; Biomarkers; Blood Platelets; Cardiovascular Diseases; Dual Anti-Platelet Therapy; Female; Flow Cytometry; Humans; Male; Middle Aged; Obesity; P-Selectin; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Platelet Glycoprotein GPIIb-IIIa Complex; Stents; Thromboxane B2; Time Factors; Treatment Outcome

The current study aimed to investigate the effect of Citrullus colocynthis (C. colocynthis) hydro-alcoholic extract on blood haemostasis in control and high-fat diet (HFD) induced obese rats. In control rats, the extract significantly enhanced bleeding time and plasma levels of tPA and significantly decreased plasma levels PAI-1 and serum levels of thromboxane B2 leading to inhibition of platelets aggregation. In HFD induced obese rats, similar effects were seen and the extract was also able to reverse HFD induced increases in fibrinogen and VWF. Searching for the mechanism, C. colocynthis acts by (1) inhibiting of food intake, (2) inhibiting the activity of pancreatic lipase, (3) decreasing levels of TNF-α and IL-6 and (4) decreasing circulatory levels of the prothrombotic adipokine, leptin and enhanced circulatory levels of the antithrombic adipokines and adiopnectin. In conclusion, C. colocynthis has antiplatelets and profibrinolytic activity in both control and HFD induced obese rats.

Topics: Animals; Anti-Obesity Agents; Antifibrinolytic Agents; Appetite Depressants; Biomarkers; Bleeding Time; Citrullus colocynthis; Diet, High-Fat; Dietary Supplements; Feces; Fibrinolysis; Fruit; Lipid Metabolism; Male; Obesity; Plant Extracts; Plasminogen Activator Inhibitor 1; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats, Sprague-Dawley; Thromboxane B2; Tissue Plasminogen Activator

Topics: Aspirin; Diabetes Mellitus, Type 2; Humans; Obesity; Platelet Aggregation Inhibitors; Thromboxane B2

Dietary conjugated linoleic acid (CLA) reduces indicators of early renal disease progression and the associated elevated cyclooxygenase (COX) levels in young obese rats with obesity-associated nephropathy (OAN). Therefore, renal function and injury and COX and its metabolites were assessed in obese fa/fa Zucker rats with more advanced renal disease. Obese rats at 16 weeks of age were provided with either cis(c)9, trans(t)11 (fa/fa-9,11) or t10,c12 (fa/fa-10,12) CLA for 8 weeks, and compared to lean (lean-CTL) and obese (fa/fa-CTL) rats provided the control diet without CLA. Obese rats displayed significantly reduced renal function and increased renal injury compared to lean rats. In the obese rat groups, glomerular hypertrophy was reduced in both CLA-supplemented groups. While all other measures of renal function or injury were not different in fa/fa-9,11 compared to fa/fa-CTL rats, the fa/fa-10,12 rats had greater renal hypertrophy, glomerular fibrosis, fibrosis, tubular casts and macrophage infiltration compared to the fa/fa-CTL and fa/fa-9,11 groups. The fa/fa-10,12 group also had elevated levels of renal COX1, which was associated with increased levels of two oxylipins produced by this enzyme, 6-keto-prostaglandin F(1α), and thromboxane B₂. Renal linoleic acid and its lipoxygenase products also were lower in obese compared to lean rats, but CLA supplementation had no effect on these or any other lipoxygenase oxylipins. In summary, supplementation with c9,t11 CLA did not improve more advanced OAN and t10,c12 CLA worsened the renal pathology. Altered production of select COX1 derived oxylipins was associated with the detrimental effect of the t10,c12 isomer.

Topics: 6-Ketoprostaglandin F1 alpha; Aging; Animals; Cyclooxygenase 1; Dietary Supplements; Disease Progression; Fibrosis; Hypertrophy; Kidney; Linoleic Acids, Conjugated; Macrophage Activation; Membrane Proteins; Obesity; Oxylipins; Rats, Zucker; Renal Insufficiency; Severity of Illness Index; Thromboxane B2

Topics: Gastroplasty; Humans; Laparoscopy; Obesity; Oxidative Stress; Platelet Activation; Thromboxane B2

Steatosis accentuates the severity of hepatic ischemia-reperfusion injury (IRI). 3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors ("statins") protect the heart and brain against post-ischemic injury, without necessarily lowering serum cholesterol. We tested whether 10-day or 1-day atorvastatin administration protects livers with fatty change or non-alcoholic steatohepatitis (NASH) against IRI.. Mice with dietary or genetic simple steatosis (SS) or NASH were subjected to 60 min of partial hepatic ischemia/24-h reperfusion, with/without atorvastatin administered with food (5 mg/kg body weight) for 10 days, or injected intravenously (5 mg/kg) 24 h before ischemia. Liver injury, Toll-like receptor-4 (TLR4), cytokines/chemokines, endothelial nitric oxide synthase (eNOS), activation and thromboxane B2 production were determined.. Atorvastatin conferred 70-90% hepatic protection against IRI in obese animals with SS or NASH, in which IRI was accentuated twofold to fivefold. IRI markedly upregulated TLR4 and activated nuclear factor-κB (NF-κB); atorvastatin abrogated these effects, as well as activating eNOS. Atorvastatin dampened the post-ischemic induction of thromboxane B2, macrophage inflammatory protein-1a, monocyte chemotactic protein-1, tumor necrosis factor-α, interleukin (IL)-12 p40, γ-interferon, IL-6, and adhesion molecules (vascular cell adhesion molecule-1, E-selectin, vascular endothelial-cadherin), and reduced macrophage and neutrophil recruitment. There was no reduction in serum cholesterol that could explain these effects, and hepatic cholesterol was normal in these mice. A single 24-h injection of atorvastatin conferred equivalent hepatoprotection.. Statins exert major hepatoprotection against IRI in lean, fatty, and NASH livers that is not due to cholesterol removal. Rather, statins downregulate TLR4 to prevent NF-κB activation, with resultant suppression of adhesion molecules, chemokines/cytokines, and thromboxane B2 production. Short-term statin treatment is an effective, readily-available preventive agent against hepatic IRI, irrespective of obesity and fatty liver disease.

Topics: Administration, Oral; Animals; Atorvastatin; Cell Adhesion Molecules; Cytokines; Cytoprotection; Disease Models, Animal; Down-Regulation; Drug Administration Schedule; Enzyme Activation; Fatty Liver; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Injections, Intravenous; Liver; Male; Mice; Mice, Obese; NF-kappa B; Nitric Oxide Synthase Type III; Non-alcoholic Fatty Liver Disease; Obesity; Pyrroles; Reperfusion Injury; RNA, Messenger; Thromboxane B2; Time Factors; Toll-Like Receptor 4

The receptor for advanced glycation end-products (RAGE) has been implicated in obesity-related metabolic disease and accelerated atherothrombosis.. We tested the hypothesis that changes in endogenous secretory (es)RAGE levels as a result of excess adiposity and oxidative stress may contribute to enhancing platelet activation in obese women, thus increasing the cardiovascular risk.. Eighty otherwise healthy obese women and 20 nonobese women were studied.. esRAGE and plasma adiponectin were reduced in obese women [median (interquartile range), 0.18 (0.13-0.26) vs. 0.38 (0.20-0.48) ng/ml, P = 0.003; and 4.4 (2.8-6.4) vs. 10.0 (6.9-12.5) μg/ml, P < 0.0001, respectively] who also displayed higher urinary 11-dehydro-thromboxane B(2) (11-dehydro-TXB(2)) [795 (572-1089) vs. 211 (135-301) pg/mg creatinine; P < 0.0001] and 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)) [544 (402-698) vs. 149 (98-219) pg/mg creatinine; P < 0.0001] compared to nonobese women. Direct correlations between plasma adiponectin and esRAGE (Rho = 0.43; P < 0.0001) and between urinary 8-iso-PGF(2α) and 11-dehydro-TXB(2) (Rho = 0.36; P = 0.001) were observed in obese women. Moreover, plasma esRAGE and urinary 11-dehdro-TXB(2) were inversely related (Rho = -0.29; P = 0.008). On multiple linear regression analysis, urinary 8-iso-PGF(2α) and plasma esRAGE were independent predictors of urinary 11-dehydro-TXB(2). In five obese women, a short-term weight loss program gave a significant increase in esRAGE and decrease in urinary 8-iso-PGF(2α) and 11-dehydro-TXB(2).. In otherwise healthy obese women, low plasma esRAGE levels are associated with reduced circulating adiponectin and enhanced thromboxane biosynthesis, which is in part mediated by increased lipid peroxidation. Thus, excess adiposity may be implicated in RAGE hyperactivation and thromboxane-dependent platelet activation, contributing to obesity-related metabolic and vascular disease.

Topics: Adiponectin; Adult; Anthropometry; Blood Glucose; Blood Pressure; Cardiovascular Diseases; Dinoprost; Female; Humans; Linear Models; Lipid Peroxidation; Lipids; Middle Aged; Obesity; Oxidative Stress; Platelet Activation; Receptor for Advanced Glycation End Products; Receptors, Immunologic; Risk; Thromboxane B2; Weight Loss

Low-grade inflammation may potentially explain the relationship between obstructive sleep apnea syndrome (OSA) and cardiovascular events. However, the respective contribution of intermittent hypoxia and confounders, such as obesity, is still debated.. To monitor urinary leukotriene E(4) (U-LTE(4)), a validated marker of proinflammatory cysteinyl leukotriene production, in OSA; to determine the influence of obesity and other confounders on U-LTE(4) concentrations; to examine the mechanisms involved through transcriptional profiling of the leukotriene pathway in peripheral blood mononuclear cells (PBMCs); and to investigate the effect of continuous positive air pressure (CPAP) on U-LTE(4) concentrations.. We measured U-LTE(4) by liquid chromatography-tandem mass spectrometry.. The U-LTE(4) concentrations were increased (P = .019) in 40 nonobese patients with OSA carefully matched for age, sex, and body mass index (BMI) to 25 control subjects, and correlated (r = 0.0312; P = .017) to the percentage of time spent with mean oxygen saturation (SaO(2)) less than 90%. In a larger cohort of patients with OSA (n = 72), U-LTE(4) increased as a function of BMI (r = 0.445; P = .0002). In those patients, the expression levels of 5-lipoxygenase activating protein mRNA in mononuclear cells exhibited a similar pattern. A stepwise multiple linear regression analysis performed in this cohort identified BMI (P = .001; regression coefficient, 3.33) and percentage of time spent with SaO(2) <90% (P = .001; regression coefficient, 1.01) as independent predictors of U-LTE(4) concentrations. Compared with baseline, CPAP reduced by 22% (P = .006) U-LTE(4) concentrations only in patients with OSA with normal BMI.. Obesity, and to a lesser extent hypoxia severity, are determinant of U-LTE(4) production in patients with OSA.

Topics: 5-Lipoxygenase-Activating Proteins; Adult; Carrier Proteins; Chromatography, Liquid; Female; Humans; Hypoxia; Leukotriene E4; Male; Membrane Proteins; Middle Aged; Obesity; Polysomnography; Prospective Studies; RNA, Messenger; Sleep Apnea, Obstructive; Tandem Mass Spectrometry; Thromboxane B2

We tested the hypothesis that insulin resistance, per se, contributes to increased platelet activation in obesity, independently of underlying inflammation.. Obesity, insulin resistance, and atherosclerosis are closely linked phenomena associated with low-grade inflammation. Obesity is associated with persistent platelet activation in otherwise healthy women.. We performed a cross-sectional study in 40 obese and 20 non-obese healthy women using urinary thromboxane metabolite excretion as a non-invasive index of platelet activation. An index of insulin sensitivity, S(I), and plasma adiponectin, C-reactive protein (CRP), and CD40 ligand (CD40L) levels were measured.. Obese women had significantly (p < 0.0001) higher 11-dehydro-thromboxane B2 (11-dehydro-TXB2) excretion (median 718 vs. 211 pg/mg creatinine), CRP (1.13 vs. 0.48 mg/l), and CD40L levels (4.45 vs. 0.90 ng/ml) than controls. Obese women had lower S(I) (median 2.51 vs. 5.0 10(4) min(-1)/[microU/ml], p < 0.002) and adiponectin (6.3 vs. 10 microg/ml, p < 0.01) than control subjects. On multiple regression analysis, waist-to-hip ratio (beta = 0.27, p < 0.05) and S(I) (beta = -0.72, p < 0.04) predicted 11-dehydro-TXB2 excretion rate, independently of adiponectin, CRP, CD40L, and lipid patterns. In order to investigate the cause-effect relationship of these associations, we examined the effects of a 12-week weight loss program or a 3-week pioglitazone treatment on urinary 11-dehydro-TXB2 in 10 women with impaired S(I) and visceral obesity. Successful weight loss (0.6 kg loss/week) achieved in 5 subjects was associated with increased S(I) (+92%) and decreased CD40L (-27%), CRP (-37%), and 11-dehydro-TXB2 (-53%) (p < 0.05). Consistently, improvement of insulin sensitivity achieved with pioglitazone significantly decreased urinary 11-dehydro-TXB2 excretion (-43%, p < 0.05) without changes in body weight.. Insulin resistance is a major determinant of platelet activation in female obesity.

Topics: Adult; Cross-Sectional Studies; Female; Humans; Insulin Resistance; Middle Aged; Obesity; Platelet Activation; Thromboxane B2

Cyclooxygenase (COX) isoforms, COX-1 and COX-2, are involved in production of prostanoids in the kidney. Increases in renal COX-2 expression have been implicated in the pathophysiology of progressive renal injury, including type 1 diabetes. Thromboxane A(2) (TxA(2)) has been suggested as the key mediator of these effects resulting in up-regulation of prosclerotic cytokines and extracellular matrix proteins. Unlike type 1 diabetes, renal COX has not been studied in models of type 2 diabetes.. Renal cortical COX protein expression, and urinary excretion of stable metabolites of prostaglandin E(2) (PGE(2)) and TxA(2), in association with metabolic parameters, were determined in 4-and 12-week-old Zucker fatty rats (fa/fa rat) (ZDF4 and ZDF12), a model of type 2 diabetes, and in age-matched littermates with no metabolic defect (Zucker lean) (ZL4 and ZL12).. Western blotting revealed increased COX-2 expression in ZDF4 as compared to ZL4 (245 +/- 130%) (P < 0.05). This increase in COX-2 was even more apparent in 12-week-old ZDF rats (650 +/- 120%) (P < 0.01). All groups of rats demonstrated COX-2-positive cells in typical cortical localizations [macula densa, thick ascending loop of Henle (TALH)]. In contrast to COX-2, COX-1 expression was 30% lower in ZDF12. These changes in COX expression were associated with enhanced urinary excretion of prostanoids, in parallel with the development of metabolic abnormalities. Moreover, increases in prostanoid excretion in ZDF12 were in part reduced by wortmannin (100 mug/kg), used as inhibitor of insulin signaling.. Renal cortical COX-2 protein expression and function were increased in ZDF rats, as compared to controls, whereas COX-1 exhibited opposite regulation. The changes in COX-2 paralleled metabolic abnormalities, and were at least in part a four consequence of hyperinsulinemia. These abnormalities may play a role in renal pathophysiology in this model of type 2 diabetes.

Topics: Androstadienes; Animals; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Fatty Acids, Nonesterified; Kidney; Membrane Proteins; Obesity; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Zucker; Thromboxane B2; Wortmannin

To determine cytochrome P450 (CYP450) and cyclooxygenase (COX) expression and metabolite regulation and renal damage in the early stages of obesity-related hypertension and diabetes.. Obese and lean Zucker rats at 10 to 12 weeks of age were studied. Blood pressure was measured in the conscious state using radiotelemetry. Blood glucose levels and body weight were measured periodically. Protein expression of CYP450 and COX enzymes in the kidney cortex, renal microvessels, and glomeruli was studied. The levels of CYP450 and COX metabolites in urine were measured, and urinary albumin excretion, an indicator of kidney damage, was measured.. Body weight and blood glucose averaged 432 +/- 20 grams and 105 +/- 5 mg/dl, respectively, in obese Zucker rats as compared with 320 +/- 8 grams and 91 +/- 5 mg/dl, respectively, in age-matched 10- to 12-week-old lean Zucker rats. Renal microvascular CYP4A and COX-2 protein levels were increased 2.3- and 17.0-fold, respectively, in obese Zucker rats. The protein expression of CYP2C11 and CYP2C23 was decreased 2.0-fold in renal microvessels isolated from obese Zucker rats when compared with lean Zucker rats. The urinary excretion rate of thromboxane B(2) was increased significantly in obese Zucker as compared with lean Zucker rats (22.0 +/- 1.8 vs. 13.4 +/- 1.0 ng/d). Urinary albumin excretion, an index of kidney damage, was increased in the obese Zucker rat at this early age.. These results suggest that increased CYP4A and COX-2 protein levels and decreased CYP2C11 and CYP2C23 protein levels occur in association with microalbuminuria during the onset of obesity-related hypertension and type 2 diabetes.

Topics: Albuminuria; Animals; Aryl Hydrocarbon Hydroxylases; Blood Glucose; Body Weight; Cyclooxygenase 2; Cytochrome P-450 CYP2J2; Cytochrome P-450 Enzyme System; Cytochrome P450 Family 2; Diabetes Mellitus, Type 2; Hypertension; Isoenzymes; Kidney; Kidney Cortex; Kidney Glomerulus; Male; Microcirculation; Obesity; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Zucker; Steroid 16-alpha-Hydroxylase; Thromboxane B2

The aim of this study was to evaluate the effects of transdermal hormone replacement therapy on some biological cardiovascular risk factors, specifically the thromboxane B2 levels, plasma viscosity and the lipid profile. Furthermore, we investigated the Doppler flow modifications at the level of the uterine artery, the internal carotid, the ophthalmic and the bladder wall arteries, and we finally evaluated whether there were significant differences in the examined parameters between normal and overweight postmenopausal women. Forty-five postmenopausal women (mean age+/-standard deviation, 53.5+/-3.8 years) participated in the study and were divided into two groups (27 with a body mass index of < 25 kg/m2 and 18 with a body mass index of > 25 kg/m2). Patients were treated with a continous estradiol transdermal supplement and a 12-day course of medroxyprogesterone acetate every 2 months, and were studied at baseline and after 6 months (in the estrogen-only phase of the second cycle). Our results showed a beneficial effect of hormone substitution on plasma viscosity, thromboxane B2 levels and lipid profile after 6 months of therapy and significant improvements of Doppler flow parameters in the examined vessels. Furthermore, we observed a lower impact of the treatment in overweight women. In conclusion, obesity represents an additional cardiovascular risk condition and it can only partially be modified by the administration of hormone replacement therapy.

Topics: Administration, Cutaneous; Blood Viscosity; Body Mass Index; Cardiovascular Diseases; Endometrium; Estradiol; Estrogen Replacement Therapy; Female; Humans; Lipids; Medroxyprogesterone Acetate; Middle Aged; Obesity; Postmenopause; Pulsatile Flow; Risk Factors; Thromboxane B2; Triglycerides; Ultrasonography, Doppler, Color; Urinary Bladder; Vascular Resistance

Regular exercise is recommended for the non-pharmacological treatment of hypertension, but the mechanisms underlying the lowering of blood pressure remain controversial. Therefore, we studied the effects of 22-week-long training on blood pressure, arterial reactivity, and metabolic abnormalities in a model of genetic obesity and moderate hypertension.. Obese and lean Zucker rats were subjected to treadmill exercise from 8 to 30 weeks of age. Blood pressures were measured by the tail-cuff method, and urine was collected in metabolic cages. At the end of the study, the samples for biochemical determinations were taken, and reactivity of isolated mesenteric and carotid arterial rings was examined in standard organ chambers.. The exercise prevented the elevation of blood pressure which was observed in non-exercised obese Zucker rats, and also reduced blood pressure in the lean rats. The relaxations of norepinephrine-preconstricted mesenteric and carotid arterial rings to acetylcholine and nitroprusside were clearly improved by exercise in the obese rats. In the lean rats exercise enhanced vasorelaxation to nitroprusside in the mesenteric and carotid rings, and to acetylcholine in the carotid preparations. The exercise-induced improvement of endothelium-mediated dilatation to acetylcholine was abolished by nitric oxide synthesis inhibition with NG nitro-L-arginine methyl ester, but not by cyclooxygenase inhibition with diclofenac or functional inhibition of endothelium-dependent hyperpolarization by precontractions with KCl. The urinary excretion of the systemic prostacyclin metabolite (2,3-dinor-6-ketoprostaglandin F1 alpha) was increased two-fold by exercise in the obese and lean rats, whereas that of the thromboxane A2 metabolite (11-dehydrothromboxane B2) remained unaffected. Treadmill training reduced blood glucose, cholesterol, and triglycerides, but did not affect the high levels of insulin in obese Zucker rats.. These results suggest that the antihypertensive effect of long-term exercise in experimental obesity related hypertension is associated with improved vasodilatation. This is expressed as enhanced relaxation via endogenous and exogenous nitric oxide, and increased endothelial prostacyclin production. The improved control of arterial tone after training could be attributed to the alleviation of hyperlipidemia and insulin resistance, whereas hyperinsulinaemia per se remained unaffected.

Topics: 6-Ketoprostaglandin F1 alpha; Acetylcholine; Analysis of Variance; Animals; Blood Glucose; Carotid Arteries; Cholesterol; Cyclooxygenase Inhibitors; Diclofenac; Endothelium, Vascular; Hypertension; In Vitro Techniques; Insulin; Male; Mesenteric Arteries; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Nitroprusside; Obesity; Physical Exertion; Rats; Rats, Zucker; Thromboxane B2; Triglycerides; Vasodilation; Vasodilator Agents

1. The obese fa/fa Zucker rat is a genetic model of obesity and insulin resistance which develops a number of metabolic and endocrine features of non-insulin-dependent diabetes, including hypertension, proteinuria and glomerular sclerosis. 2. We have investigated the urinary excretion of the metabolites of thromboxane (thromboxane B2) and prostacyclin (6-keto prostaglandin F1 alpha), and of endothelin and cyclic GMP as markers for changes in the balance of renal haemodynamic factors in the obese Zucker rat. 3. Obese fa/fa Zucker rats were hypertensive compared with their lean counterparts (161 +/- 3 and 138 +/- 3 mmHg respectively, P < 0.01); obese animals were also markedly proteinuric (16.7 +/- 6.7 versus 1.1 +/- 0.1 mg/ml) and albuminuric (8.3 +/- 2.9 versus 0.4 +/- 0.25 mg/ml) and excreted less creatinine than lean animals (all P < 0.01). Urinary excretion of endothelin was greater in obese rats (123 +/- 24 versus 62 +/- 10 pg/15 h, P < 0.05) as was the level of pre-proendothelin mRNA, but excretion of cyclic GMP was depressed (12.5 +/- 1.6 versus 27.2 +/- 3.1 nmol/ 15 h, P < 0.01). Histological examination of kidneys from obese animals showed evidence of focal glomerulosclerosis and cortical tubular damage. 4. These results show that increased urinary endothelin is associated with proteinuria and early stage nephropathy in this animal model of non-insulin-dependent diabetes mellitus. This finding, coupled with a decreased excretion of cyclic GMP, suggests that these increased renal vasoconstrictor/vasodilator forces might contribute to the renal functional changes in non-insulin-dependent diabetes mellitus.

Topics: 6-Ketoprostaglandin F1 alpha; Albuminuria; Animals; Cyclic GMP; Diabetes Mellitus; Diabetes Mellitus, Type 2; Endothelin-1; Immunohistochemistry; Kidney; Male; Obesity; Rats; Rats, Zucker; RNA, Messenger; Statistics, Nonparametric; Thromboxane B2

The authors observed the changes pf symptoms and signs, obesity index, lipid index (TC, TG, LDL-C, HDL-C), atherosclerosis in dex (AL), ratio of waist centimetre to hip centimetre (W. C/H. C). TXB2 and 6-Keto-PGF1 alpha in 34 simple obesity patients complicated with hyperlipidemia before and after acupuncture so as to make clear the influence of acupuncture on pathogenic factors led up to circular diseases. The results showed that the marked weight loss effect was achieved in the cases by acupuncture, while the level of TC, TG, LDL-C, HDL-C, AI, W.C./H.C, TXB2, 6-Keto-PGF1 alpha in the patients were finely regulated. It suggests that the acupuncture treatment not only treated obesity and hyperlipidemia, but also resisted the pathogenic factors led up to circular diseases.

Topics: 6-Ketoprostaglandin F1 alpha; Acupuncture Therapy; Adult; Aged; Female; Humans; Hyperlipidemias; Infant; Male; Middle Aged; Obesity; Thromboxane B2

A selective inhibitor of thromboxane synthase, Ro 22-3581 has been shown to be a useful tool for investigating the relationship between hyperinsulinemia and obesity. These studies have established that the pharmacologic normalization of the hyperinsulinemia associated with elevated weights in genetically obese and diet-induced obese rats resulted in decreased weight gain or weight loss. This effect was shown to be reversible, partially independent of the suppression of food intake, dependent on a functional endocrine pancreas, and not diabetogenic. However, these studies have not established a cause and effect relationship between the inhibition of thromboxane synthase activity by Ro 22-3581 and its suppression of insulin secretion and circulating insulin levels.

Topics: Animals; Body Weight; Diabetes Mellitus, Experimental; Imidazoles; Insulin; Obesity; Rats; Rats, Zucker; Thromboxane B2; Thromboxane-A Synthase

1. Lean (ln/ln) and obese (ob/ob) mice were given diets containing a fat source of 100 g evening primrose (Oenothera biennis) oil (fatty acids 18:2n-6, 18:3n-6; EPO) or 100 g cod liver oil (20:5n-3, 22:6n-3; CLO)/kg diet. 2. Weight gain was lower in the ob/ob mice fed on CLO, an effect unrelated to food intake. 3. In the ob/ob mice fed on CLO, thromboxane synthesis by clotting platelets was reduced compared with that in ob/ob mice fed on EPO. 4. The ob/ob CLO-fed mice had lower arachidonic acid but higher levels of n-3 fatty acids in liver, brown adipose tissue and white adipose tissue. 5. The n-3 fatty acids in CLO therefore replaced the n-6 fatty acids in tissue lipids and reduced synthesis of '2 series' prostaglandins in addition to causing lower weight gain in the CLO-fed ob/ob mice.

Topics: Animals; Body Weight; Fatty Acids; Fatty Acids, Essential; Lipids; Male; Mice; Mice, Inbred C57BL; Obesity; Phospholipids; Thromboxane B2

Topics: Adenosine Diphosphate; Animals; Aorta; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Collagen; Epoprostenol; Obesity; Platelet Aggregation; Prostaglandins; Rats; Rats, Zucker; Thromboxane B2; Thromboxanes