Postprandial hypertriglyceridemia and oxidative stress in patients of type 2 diabetes mellitus with macrovascular complications

Meta-Inflammation and New Anti-Diabetic Drugs: A New Chance to Knock Down Residual Cardiovascular Risk

Type 2 diabetes mellitus (DM) represents, with its macro and microvascular complications, one of the most critical healthcare issues for the next decades. Remarkably, in the context of regulatory approval trials, sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) proved a reduced incidence of major adverse cardiovascular events (MACEs), i.e., cardiovascular death and heart failure (HF) hospitalizations. The cardioprotective abilities of these new anti-diabetic drugs seem to run beyond mere glycemic control, and a growing body of evidence disclosed a wide range of pleiotropic effects. The connection between diabetes and meta-inflammation seems to be the key to understanding how to knock down residual cardiovascular risk, especially in this high-risk population. The aim of this review is to explore the link between meta-inflammation and diabetes, the role of newer glucose-lowering medications in this field, and the possible connection with their unexpected cardiovascular benefits.

Pharmacogenetic impact of SLC22A1 gene variant rs628031 (G/A) in newly diagnosed Indian type 2 diabetes patients undergoing metformin monotherapy

OBJECTIVES

Type 2 diabetes (T2D) imposes an enormous burden all over the world in both developed and developing countries. Inter-individual differences are attributed to polymorphisms in candidate genes resulting in altered absorption, transportation, distribution, and metabolism of oral antidiabetic drugs (OADs). Hence, the present study was undertaken to evaluate the pharmacogenetic impact of SLC22A1 gene variant rs628031 (G/A) on metformin monotherapy in newly diagnosed untreated T2D patients.

METHODS

Newly diagnosed T2D patients ( n  = 500) were enrolled according to inclusion/exclusion criteria. Initially, enrolled subjects were prescribed metformin monotherapy and followed up for at least 12 weeks. Response to metformin was evaluated in 478 patients who revisited for follow-up by measuring HbA1c.

RESULT

Out of 478 patients, 373 were responders to metformin monotherapy while 105 were non-responders. The pharmacogenetic impact was evaluated by genotype, haplotype, and pharmacogenetic analyses. 'GG' genotype and 'G' allele of SLC22A1 rs628031 G/A were observed in 48.8% and 67.7% of Met responders, respectively, while 20.9% and 49.1 % were in non-responders. Therefore, there was a 2.18-fold increase in the success rate of Met therapeutics.

CONCLUSION

Individuals carrying the 'GG' genotype or 'G' allele for SLC22A1 gene variant rs628031 G/A are better responders for Metformin monotherapy.

Postprandial endothelial dysfunction and CIMT after oral fat challenge in patients with type 2 diabetes mellitus with and without macrovascular disease - A preliminary study

BACKGROUND

Very few studies have reported on association of postprandial lipids and endothelial dysfunction among patients with diabetes. Whether endothelial dysfunction particularly postprandial FMD is worse in patients with T2DM with macrovascular disease compared to those without and whether this difference is related to postprandial hypertriglyceridemia (PPHTg) is unclear. Therefore, present study was aimed to assess the relationship between PPHTg and endothelial function in patients with T2DM with and without macrovascular disease.

METHOD

Endothelial dysfunction by FMD and CIMT were compared in patients with T2DM with and without macrovascular disease (n = 13 each group) and 13 age, sex and BMI matched healthy individuals after an oral fat challenge.

RESULTS

There was significant postprandial deterioration of FMD 4-hr after fat challenge in patients with diabetes (P < 0.001) as well as healthy individuals (P = 0.004). Patients with diabetes with macrovascular disease had significantly lower fasting (5.7 ± 6.1% vs. 22.7 ± 10.0% and vs. 24.7 ± 5.3%) as well as postprandial (4-hr) (3.1 ± 5.0% vs. 15.3 ± 8.1% and vs. 15.4 ± 5.7%) FMD compared to other two groups. Fasting, postprandial as well as change in FMD and CIMT in patients with diabetes correlated significantly with fasting as well as postprandial triglycerides with stronger correlation in those with macrovascular disease.

CONCLUSION

Study found significant endothelial dysfunction by FMD that shows substantial further deterioration postprandially following high fat meal in patients with diabetes with macrovascular disease compared to patients with diabetes without macrovascular disease and healthy individuals. Study also indicates that PPHTg is a contributor to endothelial dysfunction. However, more studies are required to corroborate these findings.

Mechanisms of Atherosclerosis Induced by Postprandial Lipemia

Postprandial lipemia plays an important role in the formation, occurrence, and development of atherosclerosis, and it is closely related to coronary heart disease and other diseases involving endothelial dysfunction, oxidative stress, inflammation, and other mechanisms. Therefore, it has become a focus area for further research. The studies on postprandial lipemia mainly include TG, TRL, VLDL, CM, and remnant cholesterol. Diurnal triglyceride patterns and postprandial hyperlipidemia are very relevant and are now insufficiently covered. The possible mechanisms between postprandial lipemia and cardiovascular disease have been reviewed in this article by referring to relevant literature in recent years. The research progress on the effects of postprandial lipemia on endothelial function, oxidative stress, and inflammation is highlighted. The intervention of postprandial lipemia is discussed. Non-medicinal intervention such as diet and exercise improves postprandial lipemia. As medicinal intervention, statin, fibrate, ezetimibe, omega-3 fatty acids, and niacin have been found to improve postprandial lipid levels. Novel medications such as pemafibrate, PCSK9, and apoCIII inhibitors have been the focus of research in recent years. Gut microbiota is closely related to lipid metabolism, and some studies have indicated that intestinal microorganisms may affect lipid metabolism as environmental factors. Whether intervention of gut microbiota can reduce postprandial lipemia, and therefore against AS, may be worthy of further study.

Postprandial lipemia causes oxidative stress in dogs

Oxidative stress (OS) has been strongly associated with postprandial lipemia (PPL) in humans, and still requires further investigation in dogs. However, since lipemia interferes with spectrophotometric determinations such as those used to assess OS, the present study investigated the effect of PPL on OS parameters of healthy dogs. Twenty dogs had lipemic postprandial samples compared to the average of two non-lipemic moments. Subsequently, PPL was simulated in vitro using a commercial lipid emulsion and twelve pools of non-lipemic serum of these dogs were used to simulate the minimum, median and maximum concentrations of triglycerides obtained during the lipemic state. Serum OS parameters were assessed using the antioxidants uric acid, albumin and total bilirubin; total antioxidant capacity (TAC); total oxidant capacity (TOC); and lipid peroxidation. In vivo PPL caused an increase in albumin, TAC-CUPRAC, TAC-FRAP, uric acid (p < 0.0001), TOC (p = 0.0012) and total bilirubin (p = 0.0245); reduction of TAC-ABTS (p = 0.0008); and did not alter the lipid peroxidation (p = 0.8983). In vitro, levels of albumin increased at the three lipemic concentrations (p < 0.0001), uric acid increased in the median and maximum levels (p < 0.0001), and total bilirubin concentration increased only at the maximum lipemic level (p = 0.0012). All lipemic levels tested increased TAC-ABTS (p = 0.0011) and TAC-FRAP (p < 0.0001). TAC-CUPRAC (p = 0.5002), TOC (p = 0.5938) and lipid peroxidation (p = 0.4235) were not affected by in vitro lipemia. In conclusion, both the in vivo postprandial state and in vitro simulated lipemia affect oxidative stress markers in dogs depending on the oxidative stress marker, and thus the postprandial state and/or lipemic samples should be avoided.

Family history of diabetes determines the association of HOMA-IR with fasting and postprandial triglycerides in individuals with normal glucose tolerance

BACKGROUND

Individuals with family history of diabetes carry nearly double the risk of diabetes than those without. However, the mechanism for this increased risk of diabetes in them is not fully understood.

OBJECTIVE

To study fasting and postprandial triglyceride levels in individuals with normal glucose tolerance (NGT) who had family history of diabetes and to ascertain their association with insulin resistance.

METHODS

Fasting triglyceride levels and HOMA-IR were compared in 671 NGT individuals with and without a family history of diabetes. A standardized fat challenge test was also done in one tenth of individuals of each group and postprandial triglyceride responses were compared between them. Association of HOMA-IR with fasting and postprandial triglyceride levels was ascertained through pearson's coefficient of correlation.

RESULTS

Individuals with family history of diabetes had significantly higher HOMA-IR (P < 0.001) and significantly higher postprandial triglyceride AUC (P = 0.04) after standardized fat meal despite having similar fasting triglyceride levels (P = 0.51) as those without family history of diabetes. Fasting as well as postprandial triglyceride levels significantly correlated with HOMA-IR (r = 0.35, P < 0.001 and r = 0.39, P = 0.04) only in those with a positive family history of diabetes but not in those without. Triglyceride levels mediated the associations of BMI (Δ β = -0.053) and waist circumference (Δ β = -0.075) with HOMA-IR.

CONCLUSION

Triglyceride levels, both in the fasting and the postprandial state are associated with insulin resistance in NGT individuals with a family history of diabetes but not in those without.

Fasting and postprandial lipid parameters: A comparative evaluation of cardiovascular risk assessment in prediabetes and diabetes

Context:

Dyslipidemia plays a crucial role in atherogenesis, in both prediabetes and diabetes. There persists a lacuna in the evaluation of postprandial lipid parameters in prediabetes.

Aims:

To comparatively evaluate fasting and postprandial blood lipid parameters and atherogenic lipid ratios for cardiovascular risk assessment, in prediabetes and diabetes.

Materials and Methods:

Fifty-one patients diagnosed with diabetes mellitus and thirty-two with prediabetes were selected for the study. Lipid profile and blood glucose were analyzed in fasting and postprandial blood samples.

Statistical Analysis Used:

Kolmogorov–Smirnov test, Shapiro–Wilk test, one-way ANOVA, and Pearson's regression analysis were applied.

Results:

Postprandially, triglycerides (TG) was increased significantly in diabetes compared to controls (P < 0.01) and prediabetics (P < 0.05). Among the lipid ratios, triglyceride/high density lipoprotein (TG/HDLc) was significantly increased postprandially in diabetes compared to controls (P < 0.05). A comparative analysis of fasting and postprandial parameters within each group showed a significant increase in postprandial TG/HDLc compared to the fasting state in prediabetes (P < 0.001) and diabetes (P < 0.001). Postprandial TG (P < 0.01) and TG/HDLc (P < 0.01) showed a stronger correlation with HbA_1c compared to fasting TG (P < 0.05) and TG/HDLc (P > 0.05). The prevalence of dyslipidemia and insulin resistance was higher in postprandial state than the fasting state in prediabetes and diabetes.

Conclusions:

Postprandial TG and the TG/HDLc reflect lipid abnormalities than the corresponding fasting variables in diabetes and prediabetes. Postprandial TG and TG/HDLc are better reflectors of cardiovascular status in prediabetes and diabetes.

Post-Prandial Changes in Salivary Glucocorticoids: Effects of Dietary Cholesterol and Associations with Bile Acid Excretion

Mechanisms to explain post-prandial increases in circulating glucocorticoids are not well understood and may involve increased adrenal secretion and/or altered steroid metabolism. We have compared salivary levels of cortisol and cortisone levels in healthy male and female volunteers fed either a low or cholesterol-rich midday meal. Urinary levels of steroids, bile acids and markers of lipid peroxidation were also measured. Males and females showed expected circadian changes in salivary steroids and postprandial peaks within 1h of feeding. After a high-cholesterol meal, postprandial cortisol increases were higher in males whereas post-prandial cortisone levels were higher in females. Urinary cortisol but not cortisone levels were higher on the day when males and females ate a high-cholesterol meal. Urinary bile acid excretion and anti-oxidant markers of lipid peroxidation, thiobarbituric acid reactive substances (TBARS), and total phenol content were not affected by dietary cholesterol but tended to be higher in males. Cross-tabulation of correlation coefficients indicated positive associations between urinary markers of peroxidation, bile acids, and cortisol:cortisone ratios. We conclude that dietary cholesterol (a substrate for steroidogenesis) does not have an acute effect on adrenal glucocorticoid synthesis and that gender but not a high-cholesterol meal may influence the interconversion of cortisol and cortisone. Longer term studies of the effects of dietary cholesterol are needed to analyze the associations between bile acids, steroid metabolism, and secretion and lipid peroxidation.

Deep Multi-OMICs and Multi-Tissue Characterization in a Pre- and Postprandial State in Human Volunteers: The GEMM Family Study Research Design

Cardiovascular disease (CVD) and type 2 diabetes (T2D) are increasing worldwide. This is mainly due to an unhealthy nutrition, implying that variation in CVD risk may be due to variation in the capacity to manage a nutritional load. We examined the genomic basis of postprandial metabolism. Our main purpose was to introduce the GEMM Family Study (Genetics of Metabolic Diseases in Mexico) as a multi-center study carrying out an ongoing recruitment of healthy urban adults. Each participant received a mixed meal challenge and provided a 5-hours’ time course series of blood, buffy coat specimens for DNA isolation, and adipose tissue (ADT)/skeletal muscle (SKM) biopsies at fasting and 3 h after the meal. A comprehensive profiling, including metabolomic signatures in blood and transcriptomic and proteomic profiling in SKM and ADT, was performed to describe tendencies for variation in postprandial response. Our data generation methods showed preliminary trends indicating that by characterizing the dynamic properties of biomarkers with metabolic activity and analyzing multi-OMICS data it could be possible, with this methodology and research design, to identify early trends for molecular biology systems and genes involved in the fasted and fed states.

Serum Extracellular Superoxide Dismutase Is Associated with Diabetic Retinopathy Stage in Chinese Patients with Type 2 Diabetes Mellitus

Extracellular superoxide dismutase (ecSOD) is the major extracellular scavenger of reactive oxygen species and associated with the diabetic complication in patients with type 2 diabetes mellitus (T2DM). We aimed to investigate the serum ecSOD activity in Chinese patients with different stages of diabetic retinopathy (DR) and evaluate the association between the serum ecSOD activity and the severity of DR. A total of 343 T2DM patients were categorized into three groups: nondiabetic retinopathy (NDR) group, nonproliferative diabetic retinopathy (NPDR) group, and proliferative diabetic retinopathy (PDR) group. Serum ecSOD activities were measured by the autoxidation of the pyrogallol method. In this study, 271, 46, and 26 patients were enrolled in the NDR, NPDR, and PDR groups, respectively. We found a significantly decreased trend of serum ecSOD activity among NDR subjects (118.0 ± 11.5 U/mL) compared to NPDR subjects (108.5 ± 11.9 U/mL) (P < 0.001) and NPDR subjects compared to PDR subjects (102.7 ± 12.4 U/mL) (P = 0.041). Serum ecSOD activity was an independent risk factor for DR (OR = 0.920, P < 0.001) and was associated with the progression of DR. Serum ecSOD activity might be a biomarker for DR screening and evaluation of the clinical severity of DR in Chinese T2DM patients.

Antidiabetic Effects of Tea

Diabetes mellitus (DM) is a chronic endocrine disease resulted from insulin secretory defect or insulin resistance and it is a leading cause of death around the world. The care of DM patients consumes a huge budget due to the high frequency of consultations and long hospitalizations, making DM a serious threat to both human health and global economies. Tea contains abundant polyphenols and caffeine which showed antidiabetic activity, so the development of antidiabetic medications from tea and its extracts is increasingly receiving attention. However, the results claiming an association between tea consumption and reduced DM risk are inconsistent. The advances in the epidemiologic evidence and the underlying antidiabetic mechanisms of tea are reviewed in this paper. The inconsistent results and the possible causes behind them are also discussed.

Modulatory effect of dianthrone rich alcoholic flower extract of Cassia auriculata L. on experimental diabetes

BACKGROUND

Diabetes is rapidly rising all over the world at an alarming rate and has changed from a mild disorder to major causes of mortality and morbidity in the youth and middle-aged people, and the prevalence is seen especially in six inhabited continents of the globe. The present study aims to explore the antidiabetic, lipid lowering effect of Cassia auriculata L. flowers in alloxan-induced diabetes.

METHODS

Diabetes was induced using alloxan monohydrate in experimental rats and subsequent therapeutic effects of C. auriculata extract and standard drug glibenclamide were monitored. Bioassay-directed fractionation using silica gel column chromatography was performed until pure fractions were isolated. The effect of the treatment was analyzed by hematological parameters and enzyme assays. The pure compounds were confirmed with thin layer chromatography and high performance liquid chromatography pattern and further subjected for characterization.

RESULTS

The alterations in blood glucose were monitored throughout the study. There was a gradual fall in blood glucose and significant changes were observed in lipid profile and metabolic enzyme after treatment with C. auriculata. Bioassay fractionation represented that the C2 subfraction produced a dose-dependent fall in blood glucose and lipid profile and upon further purification yielded two pure compounds. The structure of the pure compound was elucidated using Fourier transform infrared, ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, and mass spectral data.

CONCLUSION

The present study clearly indicated the significant antidiabetic effect of C. auriculata and lends support for its traditional usage without evident toxic effects.

Atherogenicity of postprandial hyperglycemia and lipotoxicity

Type 2 diabetes is characterized by a gradual decline in insulin secretion in response to nutrient loads; hence, it is primarily a disorder of postprandial glucose regulation. However, physicians continue to rely on fasting plasma glucose and glycated hemoglobin to guide management. There is a linear relationship between the risk of cardiovascular death and the 2-h oral glucose tolerance test, while a study confirms postprandial hyperglycemia as independent risk factor for cardiovascular disease in type 2 diabetes. At the same time, several studies show that postprandial hypertriglyceridemia may also be a cardiovascular risk factor. Interestingly, the simultaneous presence of postprandial hyperglycemia and postprandial hypertriglyceridemia has an additive effect in worsening endothelial function and inflammation. Evidence supports the hypothesis glucose postprandial hyperglycemia and hypertriglyceridemia may favor the appearance of the cardiovascular disease through the generation of an oxidative stress. Furthermore, clinical data suggest that postprandial hyperglycemia is a common phenomenon even in patients who may be considered in "good metabolic control". Therefore, physicians should consider monitoring and targeting postprandial plasma glucose, as well as glycated hemoglobin and fasting plasma glucose, in patients with type 2 diabetes.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.

Phenotypic flexibility as a measure of health: the optimal nutritional stress response test

Nutrition research is struggling to demonstrate beneficial health effects, since nutritional effects are often subtle and long term. Health has been redefined as the ability of our body to cope with daily-life challenges. Physiology acts as a well-orchestrated machinery to adapt to the continuously changing environment. We term this adaptive capacity “phenotypic flexibility.” The phenotypic flexibility concept implies that health can be measured by the ability to adapt to conditions of temporary stress, such as physical exercise, infections or mental stress, in a healthy manner. This may offer a more sensitive way to assess changes in health status of healthy subjects. Here, we performed a systematic review of 61 studies applying different nutritional stress tests to quantify health and nutritional health effects, with the objective to define an optimal nutritional stress test that has the potential to be adopted as the golden standard in nutrition research. To acknowledge the multi-target role of nutrition, a relevant subset of 50 processes that govern optimal health, with high relevance to diet, was used to define phenotypic flexibility. Subsequently, we assessed the response of biomarkers related to this subset of processes to the different challenge tests. Based on the obtained insights, we propose a nutritional stress test composed of a high-fat, high-caloric drink, containing 60 g palm olein, 75 g glucose and 20 g dairy protein in a total volume of 400 ml. The use of such a standardized nutritional challenge test in intervention studies is expected to demonstrate subtle improvements of phenotypic flexibility, thereby enabling substantiation of nutritional health effects.

Enhanced reduction in oxidative stress and altered glutathione and thioredoxin system response to unsaturated fatty acid load in familial hypercholesterolemia

OBJECTIVES

Familial hypercholesterolemia (FH) is characterized by increased oxidative stress (OS) levels. In the postprandial state, lipids and lipoproteins modulate OS status through their impact on pro-oxidant and antioxidant mechanisms. The objective of this study was to evaluate in patients with FH the response to an unsaturated oral fat load test (OFLT) by analyzing the mRNA levels of genes involved in the glutathione and thioredoxin antioxidant systems.

DESIGN AND METHODS

We analyzed 14 FH patients and 20 normolipidemic and normoglycemic controls. In both groups, mRNA values of antioxidant enzyme genes (glutathione and thioredoxin systems) were determined at baseline and at 2, 4, 6, and 8h after OFLT by real time PCR.

RESULTS

In the fasting state the mRNA levels of antioxidant enzymes GPX4 and the GSR, GSS, and GCLC enzymes (involved in glutathione regeneration and synthesis) and thioredoxin (TXN), were significantly increased in the FH group compared to the healthy controls. Some genes (GPX1 and GPX4) were increased at 4h in both groups, but values for the rest of the antioxidant enzyme mRNAs were decreased in FH patients after 4h from unsaturated OFLT and were increased in controls.

CONCLUSIONS

We concluded that an OFLT with predominantly unsaturated fat has a different effect on postprandial antioxidant enzyme mRNA levels in controls than in FH patients. Increased antioxidant enzyme mRNA is not the main way to reduce postprandial oxidative stress in FH. This difference could determine the influence of dietary patterns in these patients.

Tissue specific oxidative stress profile in relation to glycaemic regulation in mice

BACKGROUND

Diabetes mellitus is a metabolic disorder characterized by hyperglycaemia resulting from uncontrolled glucose regulation. Reactive oxygen species are recognized as one link between hyperglycaemia and diabetic complications. Studies have shown that diabetes mellitus is associated with decreases in antioxidant potential and increased formation of free radicals leading to oxidative stress. The present study was undertaken because an unequivocal demonstration that control of hyperglycaemia can reduce oxidative stress is still lacking.

METHODS

In the present study, we investigated oxidative stress profile of normal, streptozotocin-induced diabetic, insulin-treated and untreated diabetic animals. On the one hand, oxidative damage caused to lipids, proteins and DNA was measured. On other hand, antioxidant defense was measured in terms of specific activities of antioxidant enzymes (AOEs) and antioxidant molecules.

RESULTS

It was observed that the damage to lipids, proteins and DNA caused by free radicals increased in diabetic animals compared with that in controls. In diabetic animals not treated with insulin, damage to all biological molecules increased further significantly (p ≤ 0.005). Changes in AOEs from different tissues were complex depicting a varied AOE level in different tissues. Insulin treatment significantly improved the oxidative stress profile in all tissues studies.

CONCLUSIONS

The control of hyperglycaemia improves oxidative stress profile, that is, the ability of cells to cope up with oxidative stress.

Effect of concomitant administration of L-glutamine and cycloart-23-ene-3β, 25-diol (B2) with sitagliptin in GLP-1 (7-36) amide secretion, biochemical and oxidative stress in streptozotocin - nicotinamide induced diabetic Sprague Dawley rats

Previously we have reported that, cycloart-23-ene-3β, 25-diol (called as B2) and L-glutamine stimulated glucagon like peptide-1 (GLP-1) (7–36) amide secretion diabetic rats. The objective of present investigation was to investigate the concomitant administration of cycloart-23-ene-3β, 25-diol+sitagliptin and L-glutamine+sitagliptin in streptozotocin - nicotinamide induced diabetic Sprague Dawley. Type 2 diabetes was induced in overnight fasted male Sprague Dawley rats pre-treated with nicotinamide (100 mg/kg, i.p.) followed by administration of streptozotocin (55 mg/kg, i.p.) 20 min after. The rats were divided into; I- non-diabetic, II- diabetic control, III- Sitagliptin (5 mg/kg, p.o.)+cycloart-23-ene-3β, 25-diol (1 mg/kg, p.o.), IV- Sitagliptin (5 mg/kg, p.o.)+L-glutamine (1000 mg/kg, p.o.). The concomitant treatment of cycloart-23-ene-3β, 25-diol and L-glutamine with sitagliptin was 8 weeks. Plasma glucose, body weight, food and water intake were determined every week. Glycosylated haemoglobin, lipid profile, plasma and colonic active (GLP-1) (7–36) amide, plasma and pancreatic insulin, histology of pancreata and biomarkers of oxidative stress were measured after 8^th week treatment. Concomitant administration of cycloart-23-ene-3β, 25-diol and L-glutamine with sitagliptin significantly (p<0.001) reduced plasma glucose, glyoxylated haemoglobin, lipid profile and oxidative stress parameters compared to diabetic control groups. Both concomitant treatment increased plasma and pancreatic insulin as well as plasma and colonic active (GLP-1) (7–36) amide secretion. Histological analysis by Gomori staining observed less destruction of pancreatic β cells. The result obtained from this study; it is concluded that concomitant administration of cycloart-23-ene-3β, 25-diol+sitagliptin and L-glutamine+sitagliptin showed additive antihyperglycaemic effect in diabetic rats.

The role of oxidative stress in postprandial endothelial dysfunction

Endothelial dysfunction is a turning point in the initiation and development of atherosclerosis and its complications and is predictive of future cardiovascular events. Ingestion of high-carbohydrate or high-fat meals often results in postprandial hyperglycaemia and/or hypertriacylglycerolaemia that may lead to a transient impairment in endothelial function. The present review will discuss human studies evaluating the impact of high-carbohydrate and high-fat challenges on postprandial endothelial function as well as the potential role of oxidative stress in such postprandial metabolic alterations. Moreover, the present review will differentiate the postprandial endothelial and oxidative impact of meals rich in varying fatty acid types.

Oral L-glutamine increases active GLP-1 (7-36) amide secretion and improves glycemic control in stretpozotocin-nicotinamide induced diabetic rats

L-glutamine is a non-essential amino acid. It decreased blood sugar, stimulated insulin secretion in type 2 diabetic patients. The objective of the present investigation was to evaluate L-glutamine increases glucagon like peptide-1 (GLP-1) (7-36) amide secretion in streptozotocin-nicotinamide (STZ-NTM) induced diabetic Sprague Dawley rats. Molecular docking study was performed to elucidate the molecular basis for GLP-1 receptor agonistic activity. Type 2 diabetes was induced in overnight fasted Sprague Dawley rats pre-treated with nicotinamide (100 mg/kg, i.p.) followed by 20 min after administration of streptozotocin (55 mg/kg, i.p.). The rats were divided into; I - nondiabetic, II - diabetic control, III - sitagliptin (5 mg/kg, p.o.), IV - L-glutamine (250 mg/kg, p.o.), V - L-glutamine (500 mg/kg, p.o.) and VI - L-glutamine (1000 mg/kg, p.o.). The L-glutamine and sitagliptin treatment was 8 week. Plasma glucose was estimated every week. Body weight, food and water intake were recorded daily. Glycosylated haemoglobin, lipid profile, plasma and colonic active (GLP-1) (7-36) amide, mRNA expression of proglucagon GLP-1, plasma and pancreatic insulin, histology of pancreata and biomarkers of oxidative stress (superoxidase dismutase, reduced glutathione, malondialdehyde, glutathione peroxidase, glutathione S transferase) were measured after 8 week. In acute study, the rats were divided into I - glucose (2.5 g/kg, p.o.), II - sitagliptin (5 mg/kg, p.o.), III - L-glutamine (250 mg/kg, p.o.), IV - L-glutamine (500 mg/kg, p.o.) and V - L-glutamine (1000 mg/kg, p.o.). Plasma glucose, active GLP-1 (7-36) amide concentration and insulin levels were measured after glucose loading. The docking data indicated that l-glutamine bind to the GLP-1 receptor. L-glutamine decreased plasma glucose, increased plasma and pancreatic insulin, increased plasma and colonic active GLP-1 (7-36) amide secretion as well as decreased oxidative stress in streptozotocin-nicotinamide induced diabetic rats.

High-fat feeding, but not strenuous exercise, increases blood oxidative stress in trained men

Two prevalent origins of oxidative stress in Western society are the ingestion of high-fat meals and the performance of strenuous exercise. The purpose of this investigation was to compare the magnitude of increase in blood oxidative stress following acute feeding and acute exercise. Twelve exercise-trained men consumed a high-fat meal or performed 1 of 3 exercise bouts (steady-state aerobic; high-intensity, moderate-duration interval sprints; maximal intensity, short-duration interval sprints) in a random order, crossover design. Blood was collected before and at times following feeding and exercise. Samples were analyzed for trigylcerides, malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), advanced oxidation protein products (AOPP), nitrate/nitrite (NOx), trolox-equivalent antioxidant capacity (TEAC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). A significant condition effect was noted for MDA (p = 0.01), H(2)O(2) (p < 0.0001), and AOPP (p = 0.0006), with values highest for the meal condition. An increase of 88%, 247%, and 96% was noted from pre- to post-feeding for MDA, H(2)O(2), and AOPP, respectively. A condition effect was also noted for TEAC (p = 0.04) and CAT (p = 0.05), with values lowest for the meal condition (TEAC) and the meal and aerobic exercise condition (CAT). NOx, SOD, and GPx were relatively unaffected by feeding and exercise, while MDA, H(2)O(2), and AOPP experienced little change from pre- to postexercise (p > 0.05). These results illustrate that the magnitude of blood oxidative stress following a high-fat meal is significantly greater than that elicited by either aerobic or anaerobic exercise in a sample of exercise-trained men.

Inflammatory and oxidative stress responses to high-carbohydrate and high-fat meals in healthy humans

The postprandial state is hypothesised to be proinflammatory and prooxidative, but the relative contributions of fat versus carbohydrate are unclear. Therefore, we examined inflammation and oxidative stress responses in serum and skeletal muscle before and after 1000 kcal meals, which were high in either fat or carbohydrate in 15 healthy individuals. Serum and muscle expression of IL6 was elevated 3 hours after each meal, independently of macronutrient composition (P < 0.01). Serum IL18 was decreased after high-fat meal only (P < 0.01). Plasma total antioxidative status and muscle Cu/Zn-superoxide dismutase were decreased after high-carbohydrate meal only (P < 0.05). We conclude that a high-carbohydrate meal may evoke a greater postprandial oxidative stress response, whereas both fat and carbohydrate increased IL6. We speculate that the observed increases in postprandial IL6, without increases in any other markers of inflammation, may indicate a normal IL6 response to enhance glucose uptake, similar to its role postexercise.

Vascular consequences of a high-fat meal in physically active and inactive adults

Habitually active adults (ACT) typically exhibit lower postprandial lipemia, a condition that may attenuate oxidative stress and endothelial dysfunction following a high-fat meal (HFM), compared with inactive adults (INA). Our objective was to compare triglycerides (TAG), superoxide dismutase activity (SOD), oxidative stress (thiobarbituric reactive substances; TBARS), and brachial artery flow-mediated dilation (FMD%) before and after an HFM challenge in ACT and INA. ACT (n = 7) and INA (n = 7) subjects were matched for body mass index, age, and sex. Plasma TAG, SOD, TBARS, and FMD% were measured at baseline and 4 h after an HFM challenge. TAG significantly increased following the HFM in INA (4.15 ± 3.79 mmol·L–1 vs. 8.07 ± 5.12 mmol·L–1) and in ACT (2.16 ± 0.55 mmol·L–1 vs. 3.24 ± 1.40 mmol·L–1). Baseline TBARS were greater in ACT and remained unchanged in response to the HFM in both INA (5.1 ± 2.7 mmol·L–1 vs. 6.9 ± 2.9 mmol·L–1) and ACT (8.6 ± 2.0 mmol·L–1 vs. 7.9 ± 1.9 mmol·L–1). ACT exhibited greater SOD than INA at baseline (8.6 ± 0.7 U·mL–1 vs. 7.8 ± 0.6 U·mL–1) and following the HFM (9.3 ± 1.2 U·mL–1 vs. 8.0 ± 0.7 U·mL–1). Postprandial FMD% was decreased in INA (9.1% ± 4.0% vs. 6.2% ± 3.4%), yet remained unchanged in ACT (7.9% ± 3.7% vs. 9.3% ± 3.2%). In conclusion, the differential responses following an HFM support the concept that habitual physical activity can attenuate the negative postprandial alterations that affect vascular health.

Antidiabetic potential of α-amylase inhibitor from the seeds of Macrotyloma uniflorum in streptozotocin-nicotinamide-induced diabetic mice

CONTEXT

Macrotyloma uniflorum (Lam.) Verdc. (Leguminosae) seeds, known as the poor man's pulse crop in India, have been used as a food and also used in the traditional method for treatment of kidney stones, diabetes, obesity, etc.

OBJECTIVE

To investigate the antidiabetic effect of α-amylase inhibitor isolated from the seeds of Macrotyloma uniflorum seeds in streptozotocin-nicotinamide induced diabetic mice.

MATERIALS AND METHOD

α-Amylase inhibitor was purified using a carboxymethyl cellulose (CMC) column. Kinetic studies were done using mouse pancreatic and human salivary α-amylase. Its antidiabetic effect was studied in streptozotocin-nicotinamide-induced diabetic mice. Biochemical parameters such as serum total cholesterol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined. Histopathological investigation was performed on the pancreas, kidney, and liver tissue samples.

RESULTS

Macrotyloma uniflorum α-amylase inhibitor (MUAI) inhibited both the mouse pancreatic and human salivary α-amylase in a non-competitive manner with K(i) values of 11 and 8.8 µM and IC(50) value of 30 and 12.5 µg/mL, respectively. It decreased the serum glucose level in the treated diabetic mice. Histological findings suggested minimum pathological changes in the treated diabetic mice as compared to the diabetic control.

DISCUSSION AND CONCLUSION

The results suggest that MUAI has an antihyperglycemic activity and therefore can be used in the dietary treatment of non-insulin dependent diabetes mellitus.

Postprandial oxidative stress in response to dextrose and lipid meals of differing size

We have recently noted that ingestion of dietary lipid (in the form of heavy whipping cream) leads to greater oxidative stress than dietary carbohydrate (in the form of dextrose), when consumed in isocaloric amounts.

Objective

In the present investigation we attempted to replicate our work and also to determine the oxidative stress response to dextrose and lipid meals of two different kilocalorie (kcal) amounts.

Design

Nine young (22 ± 2 years), healthy men consumed in a random order, cross-over design one of four meals/drinks: dextrose at 75 g (300 kcals), dextrose at 150 g (600 kcals), lipid at 33 g (300 kcals), lipid at 66 g (600 kcals). Blood samples were collected Pre meal, and at 30 min, 60 min, 120 min, and 180 min post meal. Samples were assayed for glucose, triglycerides (TAG), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂). Area under the curve (AUC) was calculated for each variable, and a 4 × 5 ANOVA was utilized to further analyze data.

Results

A meal × time effect (p = 0.0002) and a time effect was noted for glucose (p < 0.0001; 30 min > Pre, 1 hr, 2 hr, and 3 hr). The dextrose meals primarily contributed to this time effect. No other effects were noted for glucose (p > 0.05). A meal effect was noted for TAG (p = 0.01; 66 g lipid meal > 75 g and 150 g dextrose meals). No other effects were noted for TAG (p > 0.05). An AUC effect was noted for MDA (p = 0.04; 66 g lipid meal > 75 g and 150 g dextrose meals). A meal × time effect (p = 0.02) and a meal effect was noted for MDA (p = 0.004; 66 g lipid meal > 75 g and 150 g dextrose meals). No time effect was noted for MDA (p = 0.72). An AUC effect was noted for H₂O₂ (p = 0.0001; 66 g lipid meal > 33 g lipid meal and 75 g and 150 g dextrose meals). A meal × time effect (p = 0.0002), a meal effect (p < 0.0001; 66 g lipid meal > 33 g lipid meal and 75 g and 150 g dextrose meals), and a time effect was noted for H₂O₂ (p < 0.0001; 2 hr > Pre, 30 min, and 1 hr; 3 hr > Pre). The time effect for H₂O₂ was primarily influenced by the 66 g lipid meal.

Conclusions

These data indicate that 1) minimal oxidative stress is observed following ingestion of dextrose loads of either 75 g or 150 g, or a lipid load of 33 g and 2) lipid ingestion at 66 g leads to greater oxidative stress than lipid at 33 g or dextrose at either 75 g or 150 g. Hence, in a sample of young and healthy men, only 66 g of lipid (taken in the form of heavy whipping cream) leads to a significant increase in blood oxidative stress, as measured by MDA and H₂O₂.

Postprandial lipaemia, oxidative stress and endothelial function: a review

AIMS

Postprandial lipaemia-induced endothelial dysfunction is felt to be mediated by increases in oxidative stress. In this review, we have examined the cross-sectional relationships found among these three variables.

METHODS

We found 20 studies conducted by 16 independent investigative teams through a Medline search from 1980 to 2008; studies were required to report correlations between at least two of the three variables of interest in studies of humans. This review is divided into (i) discussions on the biomarkers and other measures of postprandial lipaemia, oxidative stress and endothelial function; (ii) associations reported among the three variables; and (iii) other considerations including alternative intervention studies.

RESULTS

Triglycerides and free fatty acids are robust and well-standardised biomarkers of lipaemia. Measures of oxidative stress ranged from electron spin techniques to measures of lipid peroxidation and are limited by lack of standardisation. Brachial artery flow-mediated dilatation is the most commonly used measure of endothelial function. The associations between postprandial lipaemia and oxidative stress and between postprandial lipaemia and endothelial function are strong and consistent. However, the association between postprandial oxidative stress and endothelial function appears weak, at least using current approaches to measurement of oxidative stress.

DISCUSSION AND CONCLUSIONS

These observations are consistent with the proposed concept that oxidative stress mediates the adverse effects of postprandial lipaemia on endothelial function; they are limited by the difficulties in measuring oxidative stress. Efforts directed at optimising and standardising the measurement of oxidative stress will be of value in future works in this area.

Mitochondrial ATP-sensitive K(+) channels as redox signals to liver mitochondria in response to hypertriglyceridemia

We have recently demonstrated that hypertriglyceridemic (HTG) mice present both elevated body metabolic rates and mild mitochondrial uncoupling in the liver owing to stimulated activity of the ATP-sensitive potassium channel (mitoK(ATP)). Because lipid excess normally leads to cell redox imbalance, we examined the hepatic oxidative status in this model. Cell redox imbalance was evidenced by increased total levels of carbonylated proteins, malondialdehydes, and GSSG/GSH ratios in HTG livers compared to wild type. In addition, the activities of the extramitochondrial enzymes NADPH oxidase and xanthine oxidase were elevated in HTG livers. In contrast, Mn-superoxide dismutase activity and content, a mitochondrial matrix marker, were significantly decreased in HTG livers. Isolated HTG liver mitochondria presented lower rates of H(2)O(2) production, which were reversed by mitoK(ATP) antagonists. In vivo antioxidant treatment with N-acetylcysteine decreased both mitoK(ATP) activity and metabolic rates in HTG mice. These data indicate that high levels of triglycerides increase reactive oxygen generation by extramitochondrial enzymes that promote mitoK(ATP) activation. The mild uncoupling mediated by mitoK(ATP) increases metabolic rates and protects mitochondria against oxidative damage. Therefore, a biological role for mitoK(ATP) as a redox sensor is shown here for the first time in an in vivo model of systemic and cellular lipid excess.

Sage tea drinking improves lipid profile and antioxidant defences in humans

Salvia officinalis (common sage) is a plant with antidiabetic properties. A pilot trial (non-randomized crossover trial) with six healthy female volunteers (aged 40–50) was designed to evaluate the beneficial properties of sage tea consumption on blood glucose regulation, lipid profile and transaminase activity in humans. Effects of sage consumption on erythrocytes’ SOD and CAT activities and on Hsp70 expression in lymphocytes were also evaluated. Four weeks sage tea treatment had no effects on plasma glucose. An improvement in lipid profile was observed with lower plasma LDL cholesterol and total cholesterol levels as well as higher plasma HDL cholesterol levels during and two weeks after treatment. Sage tea also increased lymphocyte Hsp70 expression and erythrocyte SOD and CAT activities. No hepatotoxic effects or other adverse effects were observed.

Antioxidant enzyme activity and coronary heart disease: meta-analyses of observational studies

Controversial data exist concerning the relation between the activities of scavenger antioxidant enzymes and coronary heart disease (CHD) risk. The authors report updated meta-analyses of studies assessing the activities of 3 antioxidant enzymes--glutathione peroxidase, superoxide dismutase, and catalase--and CHD risk. Computer-based and manual searches of the relevant literature from January 1966 to January 2008 were performed. Studies assessing glutathione peroxidase, superoxide dismutase, and catalase activities in cells or biologic fluids and clinical CHD outcomes were selected. Pooled odds ratios for CHD were calculated by using an inverse-variance-weighted random-effects model. Forty-two case-control studies and 3 prospective studies were included. The pooled odds ratios for CHD associated with a 1-standard-deviation increase in glutathione peroxidase, superoxide dismutase, and catalase activity levels were 0.51 (95% confidence interval: 0.35, 0.75), 0.48 (95% confidence interval: 0.32, 0.72), and 0.32 (95% confidence interval: 0.16, 0.61), respectively, with substantial between-study heterogeneity (I(2) > 90% for the 3 enzymes). These findings were remarkably robust in the sensitivity analysis. The authors' meta-analyses support an inverse association between circulating levels of superoxide dismutase, glutathione peroxidase, and catalase activities with CHD and emphasize the need for additional high-quality prospective studies.

Postprandial oxidative stress in exercise trained and sedentary cigarette smokers

Cigarette smokers experience an exaggerated triglyceride (TAG) and oxidative stress response to high fat feeding. Exercise training may serve to attenuate the rise in these variables, by improving TAG clearance and antioxidant defense. We compared blood TAG, antioxidant capacity, and oxidative stress biomarkers in exercise trained (>2 hrs per wk) and untrained smokers matched for age, in response to a high fat test meal. We report here that low volume exercise training can attenuate postprandial lipid peroxidation, but has little impact on blood TAG and other markers of oxidative stress. Higher volumes of exercise may be needed to allow for clinically meaningful adaptations in postprandial lipemia and oxidative stress.

Postprandial lipaemia in patients with impaired fasting glucose, impaired glucose tolerance and diabetes mellitus

AIMS

To compare the postprandial lipid responses in subjects with prediabetes (IFG and IGT), newly detected diabetes mellitus (NDDM) and normal glucose tolerance (NGT).

METHODS

Postprandial lipid responses to a standard oral fat challenge was studied in forty-four subjects who were divided after an OGTT into NGT, pure impaired fasting glucose (PIFG), pure impaired glucose tolerance (PIGT) and NDDM.

RESULTS

There was a significantly higher postprandial triglyceride (PPTg) response with a higher PPTg area under curve (p=0.004) and peak PPTg levels (p=0.003) in patients with NDDM but not with either PIFG (p>0.05) or PIGT (p>0.05) when compared with NGT. Overall, PPTg responses correlated significantly with fasting plasma glucose (p=0.001) and 2h plasma glucose (p=0.001) but not with age, sex, body mass index, waist, or insulin resistance.

CONCLUSION

Subjects with newly detected diabetes mellitus displayed postprandial hypertriglyceridemia after a standard oral fat meal challenge while no such abnormality could be demonstrated in subjects with IFG or IGT. This defect is probably related to glycemic status and insulin resistance.

PPARgamma mRNA expression is reduced in peripheral blood mononuclear cells after fat overload in patients with metabolic syndrome

PPARgamma is a transcriptional regulator of metabolism; its activity can be modulated by direct binding of dietary lipids. The most prevalent human PPARgamma gene variant, Ala12, is associated with postprandial hypertriglyceridemia in patients with metabolic syndrome, although the mechanism whereby this polymorphism affects lipid homeostasis remains to be fully determined. Using peripheral blood mononuclear cells (PBMC), we studied the effect of the Pro12 and Ala12 polymorphisms on mRNA expression of PPARgamma and nuclear factor kappa B genes before and 3 and 4 h after fat overload. We also studied several biochemical and oxidative stress variables. Most of the indicators of oxidative stress were higher in patients with metabolic syndrome than in healthy subjects before and after fat overload. Patients also differed depending on whether they had the Pro12 or Ala12 variant in PBMC; PPARgamma expression was lower in healthy subjects compared with patients. After fat overload, circulating triglycerides and PPARgamma expression were positively correlated (r = 0.617, P < 0.05), and PPARgamma expression tended to be negatively correlated with 2 important markers of oxidative stress: plasma lipid peroxidation (r = -0.224, P < 0.1) and carbonylated proteins (CPro) (r = -0.340, P < 0.1) concentrations. We also found differences in several indicators of oxidative stress between Pro12 and Ala12 patients, including an increase in plasma CPro before and after fat overload in Ala12 but not Pro12 patients. These data provide evidence that the Ala12 sequence variant is associated with a worse metabolic profile than Pro12. This is related to differences in the expression of PPARgamma and to oxidative imbalance after fat overload.

Postprandial oxidative stress is exacerbated in cigarette smokers

Both cigarette smoking and high fat meals induce oxidative stress, which is associated with the pathogenesis of numerous diseases. We compared blood antioxidant status, oxidative stress biomarkers and TAG in twenty smokers and twenty non-smokers, matched for age and physical activity, in response to a high fat test meal standardized to body mass. Blood samples were collected before feeding (resting and fasted) and at 1, 2, 4 and 6 h post feeding and analysed for antioxidant capacity (trolox equivalent antioxidant capacity; TEAC), xanthine oxidase activity (XO), hydrogen peroxide (H2O2), malondialdehyde (MDA) and TAG. Smoking status (P < 0.001) and time (P < or = 0.01) effects were noted for all variables, with smokers demonstrating higher values compared with non-smokers for all variables except for TEAC, for which values were lower for smokers. XO, H2O2, MDA and TAG increased following feeding with a peak response at the 4 h post feeding time point, with the opposite response occurring for TEAC. Although no interaction effects were noted (P>0.05), contrasts revealed greater values in smokers compared with non-smokers for XO, H2O2, MDA and TAG, and lower values for TEAC at times from 1-6 h post feeding (P < or = 0.05). Our findings indicate that young cigarette smokers experience an exaggerated oxidative stress response to feeding, as well as hypertriacylglycerolaemia, as compared with non-smokers. These data provide insight into another possible mechanism associating cigarette smoking with ill health and disease.

Attenuation of plasma dyslipidemia and oxidative damage by dietary caloric restriction in streptozotocin-induced diabetic rats

Oxidative stress has been proposed as the pathogenic mechanism linking insulin resistance with endothelial dysfunction during diabetes. The present study investigated the attenuation of plasma dyslipidemia and oxidative damage by caloric restriction in experimental diabetes. Forty male Wistar rats were divided into ad libitum and calorie-restricted groups. The calorie-restricted group was subjected to 30% caloric restriction for 63 days before induction of diabetes to 50% of both groups. Caloric restriction significantly (p<0.01) reduced the body weights, reactive oxygen species (ROS), catalase, total cholesterol levels and non-significantly reduced SOD activities in non-diabetic and diabetic rats. Caloric restriction was also found to improve blood glucose levels, glycated hemoglobin, malondialdehyde, triglyceride, oxidized glutathione and reduced glutathione levels and significantly (p<0.05) increased GPx and GR activities in the experimental animals. The non-diabetic rats fed ad libitum had the most significant increases in body weight which could be due to dyslipidemia. These results indicate that dietary caloric restriction attenuates the oxidative damage and dyslipidemia exacerbated during diabetes as evidenced by the significant reduction in their body weights, ROS, total cholesterol levels and the increases in GPx activity and redox status.

Dietary caloric restriction improves the redox status at the onset of diabetes in hepatocytes of streptozotocin-induced diabetic rats

Enhanced production of free radicals and oxidative stress induced by hyperglycemia play a central role in the pathogenesis of diabetes and its complications. This study assessed the attenuation by dietary caloric restriction on the oxidative and lipid peroxidative effects of diabetes in the liver through reduction in body and organ weights and concomitant metabolic changes. Three-month-old male Wistar rats were subjected to ad libitum feeding and 30% caloric restriction for 9 weeks before induction of diabetes by intraperitoneal injection of 35 mg/kg body weight streptozotocin. The animals were sacrificed 2 weeks after streptozotocin treatment depicting the onset of diabetes. Caloric restriction significantly reduced the organ weights (p<0.01), malondialdehyde (p<0.01) and catalase activity (p<0.01), but significantly increased glutathione reductase activity (p<0.01), and GSH/GSSG ratios (p<0.05). Caloric restriction also non-significantly reduced reactive oxygen species, superoxide dismutase and oxidized glutathione but increased glutathione peroxidase activity and reduced glutathione levels in the diabetic rats. Our data indicate a decrease in lipid peroxidation, improvement in the antioxidant defense systems and restoration of the redox status in the liver by caloric restriction. Therefore, this could provide a non-invasive antioxidant therapy early in diabetes to prevent the development of the complications associated with the disease.

Pomegranate juice sugar fraction reduces macrophage oxidative state, whereas white grape juice sugar fraction increases it

The antiatherogenic properties of pomegranate juice (PJ) were attributed to its antioxidant potency and to its capacity to decrease macrophage oxidative stress, the hallmark of early atherogeneis. PJ polyphenols and sugar-containing polyphenolic anthocyanins were shown to confer PJ its antioxidant capacity. In the present study, we questioned whether PJ simple or complex sugars contribute to the antioxidative properties of PJ in comparison to white grape juice (WGJ) sugars. Whole PJ decreased cellular peroxide levels in J774A.1 macrophage cell-line by 23% more than PJ polyphenol fraction alone. Thus, we next determined the contribution of the PJ sugar fraction to the decrease in macrophage oxidative state. Increasing concentrations of the PJ sugar fraction resulted in a dose-dependent decrement in macrophage peroxide levels, up to 72%, compared to control cells. On the contrary, incubation of the cells with WGJ sugar fraction at the same concentrations resulted in a dose-dependent increment in peroxide levels by up to 37%. The two sugar fractions from PJ and from WGJ showed opposite effects (antioxidant for PJ and pro-oxidant for WGJ) also in mouse peritoneal macrophages (MPM) from control as well as from streptozotocin-induced diabetic Balb/C mice. PJ sugar consumption by diabetic mice for 10 days resulted in a small but significant decrement in their peritoneal macrophage total peroxide levels and an increment in cellular glutathione content, compared to MPM harvested from control diabetic mice administrated with water. In contrast, WGJ sugar consumption by diabetic mice resulted in a 22% increment in macrophage total peroxide levels and a 45% decrement in cellular glutathione content. Paraoxonase 2 activity in macrophages increases under oxidative stress conditions. Indeed, macrophage paraoxonase 2 activity was decreased after PJ sugars supplementation, but increased after WGJ sugars supplementation. We conclude that PJ sugar fraction, unlike WGJ sugar fraction, decreases macrophage oxidative state under normal and under diabetic conditions. These antioxidant/antiatherogenic effects could be due to the presence of unique complex sugars and/or phenolic sugars in PJ.

Ameliorative effects of dietary caloric restriction on oxidative stress and inflammation in the brain of streptozotocin-induced diabetic rats

BACKGROUND

There is a strong association between oxidative stress and inflammation in the pathologies of diabetes. Recent evidence suggests that these phenomena could impair brain function. We investigated the potential role of dietary caloric restriction in ameliorating the effects of both oxidative stress and inflammation in the brain of streptozotocin-induced type 2 diabetic rats.

METHODS

Forty male Wistar rats were subjected to 30% caloric restriction (20 animals) and ad libitum feeding (20 animals) for 9 weeks before the induction of diabetes in 20 animals (10 from each group) by intraperitoneal injection of 35 mg/kg body weight streptozotocin.

RESULTS

Caloric restriction was able to significantly (p>0.05) reduce triglyceride, ROS, IL6, TNF-alpha and body weights in diabetic rats. However, no significant differences were obtained in the antioxidant enzyme (SOD, CAT and GPx) activities except in GPx where caloric restriction increased the levels in both non-diabetic and diabetic rats.

CONCLUSION

Caloric restriction was found to ameliorate the oxidative and inflammatory effects of diabetes in the brain. Non-diabetic rats feeding ad libitum were found to have increased levels of oxidative stress and inflammatory biomarkers and these could, in part, be due to their increased body weights.