β-glucans: ex vivo inflammatory and oxidative stress results after pasta intake

Background

It is well known that Mediterranean Diet can positively influence the health of each individual, in particular it is know that fibers have an important role. However, in Mediterranean cities most people do not have a close adherence to Mediterranean diet. Thus, in our study, we considered fibers like β-glucans that have been added to pasta with a percentage of 6 %. Our study aimed to evaluate the capacity of β-glucans intake on oxidative stress and inflammation in a cohort of middle aged slightly overweight subjects.

Methods

We used a longitudinal study design. The study lasted 30 days during which time, each participant acted with no food restriction. Participants underwent morning fasting blood venous sample for blood chemistry and other biological parameters at the beginning of the study and after 30 days of pasta supplemented with 6 % of β-glucan intake 4 times a week. We performed anthropometric, biochemical, oxidative stress and cytokine analysis at the beginning and the end of study.

Results

After the 30 days of pasta intake we obtained a significant decrease of LDL-cholesterol, IL-6 and AGEs levels.

Conclusion

The results confirmed a capacity of β-glucans intake to lower oxidative stress. Additional longitudinal observation on community-based cohorts are needed to confirm these data and investigate the biological mechanisms through which effects are induced, and to fully explore the therapeutic potential of β-glucans.

     

Protective effects of either C-peptide or l-arginine on pancreatic β-cell function,proliferation, and oxidative stress in streptozotocin-induced diabetic rats

Diabetes and cardiometabolic risk factors including hypertension and dyslipidemia are the major threats to human health in the 21st century. Apoptosis in pancreatic tissue is one of the major causes of diabetes type 1 progression. The aim of this study was to investigate the effects of C-peptide or l -arginine on some cardiometabolic risk factors, pancreatic morphology, function and apoptosis, and the mechanisms of their actions. Forty adult male albino rats were divided into four equal groups: 1—control nondiabetic, 2—diabetic (no treatment), 3—diabetic + C-peptide, and 4—diabetic + l -arginine. Diabetes was induced by a single intraperitoneal injection of high dose streptozotocin. At the end of the experiment, sera glucose, insulin levels, total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NO), and pancreatic MDA, TAC, and B-cell lymphoma 2 were measured. The morphology and proliferating activity of the pancreas were examined by hematoxylin and eosin histological stain, proliferative cell nuclear antigen (PCNA), and insulin antibodies. Our results showed that induction of diabetes caused hyperglycemia, dyslipidemia, and oxidative stress. However, administration of C-peptide or l -arginine significantly improved the pancreatic histopathology with a significant increase in the area % of insulin immunoreactivity, the number of PCNA immunopositive cells, the number of islets, and the diameter of islets compared with the diabetic group. C-peptide treatment of the diabetic rats completely corrected these errors, while l -arginine partially antagonized the above diabetic complications. So the administration of C-peptide as an adjuvant therapy in type 1 diabetes can significantly decrease apoptosis of pancreas and subsequent progression of diabetes complication.     

Glutathione – linking cell proliferation to oxidative stress

SignificanceThe multifaceted functions of reduced glutathione (gamma-glutamyl–cysteinyl–glycine; GSH) continue to fascinate plants and animal scientists, not least because of the dynamic relationships between GSH and reactive oxygen species (ROS) that underpin reduction/oxidation (redox) regulation and signalling. Here we consider the respective roles of ROS and GSH in the regulation of plant growth, with a particular focus on regulation of the plant cell cycle. Glutathione is discussed not only as a crucial low molecular weight redox buffer that shields nuclear processes against oxidative challenge but also a flexible regulator of genetic and epigenetic functions.Recent advancesThe intracellular compartmentalization of GSH during the cell cycle is remarkably consistent in plants and animals. Moreover, measurements of in vivo glutathione redox potentials reveal that the cellular environment is much more reducing than predicted from GSH/GSSG ratios measured in tissue extracts. The redox potential of the cytosol and nuclei of non-dividing plant cells is about −300 mV. This relatively low redox potential maintained even in cells experiencing oxidative stress by a number of mechanisms including vacuolar sequestration of GSSG. We propose that regulated ROS production linked to glutathione-mediated signalling events are the hallmark of viable cells within a changing and challenging environment.Critical issuesThe concept that the cell cycle in animals is subject to redox controls is well established but little is known about how ROS and GSH regulate this process in plants. However, it is increasingly likely that redox controls exist in plants, although possibly through different pathways. Moreover, redox-regulated proteins that function in cell cycle checkpoints remain to be identified in plants. While GSH-responsive genes have now been identified, the mechanisms that mediate and regulate protein glutathionylation in plants remain poorly defined.Future directionsThe nuclear GSH pool provides an appropriate redox environment for essential nuclear functions. Future work will focus on how this essential thiol interacts with the nuclear thioredoxin system and nitric oxide to regulate genetic and epigenetic mechanisms. The characterization of redox-regulated cell cycle proteins in plants, and the elucidation of mechanisms that facilitate GSH accumulation in the nucleus are keep steps to unravelling the complexities of nuclear redox controls.     

Bioactive eicosanoids: Role of prostaglandin F2α and F2-isoprostanes in inflammation and oxidative stress related pathology

Oxidative stress and inflammation are supposed to be the key players of several acute and chronic diseases, and also for progressive aging process. Eicosanoids, especially prostaglandin F_2α (PGF_2α) and F₂-isoprostanes are endogenous compounds that are involved both in physiology and the above mentioned pathologies. These compounds are biosynthesized mainly from esterified arachidonic acid through both enzymatic and non-enzymatic free radical-catalysed reactions in vivo, respectively. They have shown to possess potent biological activities in addition to their application as biomarkers of oxidative stress and inflammation. Recent advancement of methodologies has made it possible to quantify these compounds more reliably and apply them in various in vivo studies successfully. Today, experimental and clinical studies have revealed that both PGF_2α and F₂-isoprostanes are involved in severe acute or chronic inflammatory conditions such as rheumatic diseases, asthma, risk factors of atherosclerosis, diabetes, ischemia-reperfusion, septic shock and many others. These evidences promote that assessment of bioactive PGF_2α and F₂-isoprostanes simultaneously in body fluids offers unique non-invasive analytical opportunity to study the function of these eicosanoids in physiology, oxidative stress-related and inflammatory diseases, and also in the determination of potency of various radical scavengers, anti-inflammatory compounds, drugs, antioxidants and diet.     

Thymoquinone ameliorates chemical induced oxidative stress and β-cell damage in experimental hyperglycemic rats

The present study was aimed to investigate the effect of thymoquinone (TQ) on pancreatic insulin levels, tissue antioxidant and lipid peroxidation (LPO) status in streptozotocin (STZ) nicotinamide (NA) induced diabetic rats. Diabetes was induced in experimental rats by a single intraperitoneal (i.p) injection of STZ (45 mg/kg b.w) dissolved in 0.1 mol/L citrate buffer (pH 4.5), 15 min after the i.p administration of NA (110 mg/kg b.w). Diabetic rats exhibited increased blood glucose with significant decrease in plasma insulin levels. The activities of antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and the levels of low-molecular weight antioxidants Vitamin C, Vitamin E and reduced glutathione (GSH) were decreased while increases in the levels of lipid peroxidation markers were observed in liver and kidney tissues of diabetic control rats as compared to control rats. In addition, diabetic rats showed an obvious decrease in pancreatic insulin levels. Administration of TQ (80 mg/kg b.w) to diabetic rats for 45 days significantly reversed the damage associated with diabetes. Biochemical findings were supported by histological studies. These results indicated that TQ exerts a protective action on pancreatic beta cell function and overcomes oxidative stress through its antioxidant properties.     

A role for aberrant protein palmitoylation in FFA-induced ER stress and β-cell death

Exposure of insulin-producing cells to elevated levels of the free fatty acid (FFA) palmitate results in the loss of β-cell function and induction of apoptosis. The induction of endoplasmic reticulum (ER) stress is one mechanism proposed to be responsible for the loss of β-cell viability in response to palmitate treatment; however, the pathways responsible for the induction of ER stress by palmitate have yet to be determined. Protein palmitoylation is a major posttranslational modification that regulates protein localization, stability, and activity. Defects in, or dysregulation of, protein palmitoylation could be one mechanism by which palmitate may induce ER stress in β-cells. The purpose of this study was to evaluate the hypothesis that palmitate-induced ER stress and β-cell toxicity are mediated by excess or aberrant protein palmitoylation. In a concentration-dependent fashion, palmitate treatment of RINm5F cells results in a loss of viability. Similar to palmitate, stearate also induces a concentration-related loss of RINm5F cell viability, while the monounsaturated fatty acids, such as palmoleate and oleate, are not toxic to RINm5F cells. 2-Bromopalmitate (2BrP), a classical inhibitor of protein palmitoylation that has been extensively used as an inhibitor of G protein-coupled receptor signaling, attenuates palmitate-induced RINm5F cell death in a concentration-dependent manner. The protective effects of 2BrP are associated with the inhibition of [(3)H]palmitate incorporation into RINm5F cell protein. Furthermore, 2BrP does not inhibit, but appears to enhance, the oxidation of palmitate. The induction of ER stress in response to palmitate treatment and the activation of caspase activity are attenuated by 2BrP. Consistent with protective effects on insulinoma cells, 2BrP also attenuates the inhibitory actions of prolonged palmitate treatment on insulin secretion by isolated rat islets. These studies support a role for aberrant protein palmitoylation as a mechanism by which palmitate enhances ER stress activation and causes the loss of insulinoma cell viability.     

Role of adenosine signalling and metabolism in β-cell regeneration

Glucose homeostasis, which is controlled by the endocrine cells of the pancreas, is disrupted in both type I and type II diabetes. Deficiency in the number of insulin-producing β cells – a primary cause of type I diabetes and a secondary contributor of type II diabetes – leads to hyperglycemia and hence an increase in the need for insulin. Although diabetes can be controlled with insulin injections, a curative approach is needed. A potential approach to curing diabetes involves regenerating the β-cell mass, e.g. by increasing β-cell proliferation, survival, neogenesis or transdifferentiation. The nucleoside adenosine and its cognate nucleotide ATP have long been known to affect insulin secretion, but have more recently been shown to increase β-cell proliferation during homeostatic control and regeneration of the β-cell mass. Adenosine is also known to have anti-inflammatory properties, and agonism of adenosine receptors can promote the survival of β-cells in an inflammatory microenvironment. In this review, both intracellular and extracellular mechanisms of adenosine and ATP are discussed in terms of their established and putative effects on β-cell regeneration.     

Attenuation of Aβ-induced neurotoxicity by thymoquinone via inhibition of mitochondrial dysfunction and oxidative stress

Beta-amyloid (Aβ) peptides are considered to play a major role in the pathogenesis of Alzheimer's disease (AD) and compounds that can prevent pathways of Aβ-induced neurotoxicity may be potential therapeutic agents for treatment of AD. This study examined the hypothesis that thymoquinone (TQ) would reduce oxidative stress and mitochondrial dysfunction in differentiated pheochromocytoma (PC 12) cells exposed to Aβ fragment 25-35 (Aβ(25-35)). To test this hypothesis, Aβ was used to induce an in vitro model of AD in differentiated PC 12 cell line of rat. After 24?h of exposure with Aβ(25-35), a significant reduction in cell viability and mitochondrial membrane potential (MMP) was observed. In addition, a significant elevation in the TBARS content and nitric oxide (NO) and activity of acetylcholine esterase (AChE) was observed which was restored significantly by TQ pretreatment. Furthermore, TQ also ameliorated glutathione and its dependent enzymes (glutathione peroxidase, glutathione reductase) which were depleted by Aβ(25-35) in PC 12 cells. These results were supported by the immunocytochemical finding that has shown protection of cells by TQ from noxious effects of Aβ(25-35). These results indicate that TQ holds potential for neuroprotection and may be a promising approach for the treatment of neurodegenerative disorders including AD.     

Bcl-2 proteins in diabetes: mitochondrial pathways of β-cell death and dysfunction

Diabetes is a metabolic disease affecting nearly 300 million individuals worldwide. Both types of diabetes (1 and 2) are characterized by loss of functional pancreatic β-cell mass causing different degrees of insulin deficiency. The Bcl-2 family has a double-edged effect in diabetes. These proteins are crucial controllers of the mitochondrial pathway of β-cell apoptosis induced by pro-inflammatory cytokines or lipotoxicity. In parallel, some Bcl-2 members also regulate glucose metabolism and β-cell function. In this review, we describe the role of Bcl-2 proteins in β-cell homeostasis and death. We focus on how these proteins interact, their contribution to the crosstalk between endoplasmic reticulum stress and mitochondrial permeabilization, their context-dependent usage following different pro-apoptotic stimuli, and their role in β-cell physiology.     

Effect of anti-oxidants and oxidative stress parameters on ram semen after the freeze–thawing process

Oxidative damage to sperm resulting from reactive oxygen species generated by the cellular components of semen is one of the main causes for the decline in motility and fertility of sperm during the freeze–thawing process. The aim of this study was thus to determine the effects of anti-oxidants on standard semen parameters, lipid peroxidation (LPO) and anti-oxidant activities after the freeze–thawing of ram semen. Ejaculates collected from four Akkaraman rams, were pooled and evaluated at 33 °C. Semen samples were diluted in a Tris-based extender containing the anti-oxidants glutathione (GSH) (5 mM), oxidized glutathione (GSSG) (5 mM) or cysteine (5 mM) and an extender containing no anti-oxidants (control), cooled to 5 °C and frozen in 0.25 ml French straws. Frozen straws were thawed individually for 20 s in a water bath (37 °C) for microscopic evaluation. The use of an extender supplemented with cysteine led to the highest (P < 0.01) post-thaw motility (61.0 ± 1.9%), compared to the other treatment groups. No significant differences were observed in viability, acrosome damage and total abnormalities, and following the hypo-osmotic swelling test (HOST), following supplementation with anti-oxidants after the thawing of the semen. Following the thawing process, the levels of malondialdehyde (MDA) did not change with the addition of anti-oxidants, compared to the control. The GSH level and glutathione peroxidase (GSH-PX) activity remained significantly higher upon the addition of GSH (3.33 ± 0.14 nmol/ml and 22.02 ± 1.27 IU/g protein) and GSSG (3.24 ± 0.08 nmol/ml and 20.17 ± 3.38 IU/g protein) compared to the other treatment (P < 0.001) groups. Only cysteine significantly elevated the activity of catalase (CAT, 842.40 ± 90.42 kU/l) following the freeze–thawing process. The Vitamin E (VitE) level was significantly higher, when compared to GSSG, cysteine and the control, when GSH (4.21 ± 0.20 mg/dl) was added to the freezing extender (P < 0.001). It could be concluded that future efforts aimed on improving the efficiency of cryopreservation of ram sperm should concentrate on the use of anti-oxidant additives. The results obtained provide a new approach to the cryopreservation of ram semen, and could positively contribute to intensive sheep production.     

Insulin and glucagon regulate pancreatic α-cell proliferation

Type 2 diabetes mellitus (T2DM) results from insulin resistance and β-cell dysfunction, in the setting of hyperglucagonemia. Glucagon is a 29 amino acid peptide hormone, which is secreted from pancreatic α cells: excessively high circulating levels of glucagon lead to excessive hepatic glucose output. We investigated if α-cell numbers increase in T2DM and what factor (s) regulate α-cell turnover. Lepr(db)/Lepr(db) (db/db) mice were used as a T2DM model and αTC1 cells were used to study potential α-cell trophic factors. Here, we demonstrate that in db/db mice α-cell number and plasma glucagon levels increased as diabetes progressed. Insulin treatment (EC50 = 2 nM) of α cells significantly increased α-cell proliferation in a concentration-dependent manner compared to non-insulin-treated α cells. Insulin up-regulated α-cell proliferation through the IR/IRS2/AKT/mTOR signaling pathway, and increased insulin-mediated proliferation was prevented by pretreatment with rapamycin, a specific mTOR inhibitor. GcgR antagonism resulted in reduced rates of cell proliferation in αTC1 cells. In addition, blockade of GcgRs in db/db mice improved glucose homeostasis, lessened α-cell proliferation, and increased intra-islet insulin content in β cells in db/db mice. These studies illustrate that pancreatic α-cell proliferation increases as diabetes develops, resulting in elevated plasma glucagon levels, and both insulin and glucagon are trophic factors to α-cells. Our current findings suggest that new therapeutic strategies for the treatment of T2DM may include targeting α cells and glucagon.     

Role of energy metabolic deficits and oxidative stress in excitotoxic spinal motor neuron degeneration in?vivo

MN (motor neuron) death in amyotrophic lateral sclerosis may be mediated by glutamatergic excitotoxicity. Previously, our group showed that the microdialysis perfusion of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate) in the rat lumbar spinal cord induced MN death and permanent paralysis within 12 h after the experiment. Here, we studied the involvement of energy metabolic deficiencies and of oxidative stress in this MN degeneration, by testing the neuroprotective effect of various energy metabolic substrates and antioxidants. Pyruvate, lactate, β-hydroxybutyrate, α-ketobutyrate and creatine reduced MN loss by 50–65%, preserved motor function and completely prevented the paralysis. Ascorbate, glutathione and glutathione ethyl ester weakly protected against motor deficits and reduced MN death by only 30–40%. Reactive oxygen species formation and 3-nitrotyrosine immunoreactivity were studied 1.5–2 h after AMPA perfusion, during the initial MN degenerating process, and no changes were observed. We conclude that mitochondrial energy deficiency plays a crucial role in this excitotoxic spinal MN degeneration, whereas oxidative stress seems a less relevant mechanism. Interestingly, we observed a clear correlation between the alterations of motor function and the number of damaged MNs, suggesting that there is a threshold of about 50% in the number of healthy MNs necessary to preserve motor function.     

Acute hyperglycemia and oxidative stress: direct cause and effect?

Oxidative stress is increased in Type 2 diabetes and this appears to underlie the development of diabetic complications. Increased oxidative stress is claimed to be triggered directly by acute (sudden-onset) hyperglycemia, but published data do not clearly support a direct cause and effect relationship. In this article, published evidence of a direct prooxidant effect of acute hyperglycemia is presented and discussed in some detail, and conflicts, controversies, and problems are highlighted. Evidence for glucose variability as a possible important trigger of oxidative stress in diabetes is reviewed, with some speculation as to how the field would be advanced if there were more widespread recognition about the role that wide fluctuations in glucose concentration play in diabetic complications. Possible direct or indirect antioxidative effects of various drugs used in the treatment of diabetic subjects are discussed because these may have influenced current understanding of the link between hyperglycemia and oxidative stress. The aims are to reveal the divergence between the available evidence and the accepted view that acute hyperglycemia is a direct trigger of oxidative stress and to suggest areas of research that will help resolve current controversies in this important and challenging area.     

Role of mitochondrial dysfunction and oxidative stress in the pathogenesis of selective neuronal loss in Wernicke’s encephalopathy

Thiamine deficiency results in Wernicke’s encephalopathy and is commonly encountered in chronic alcoholism, gastrointestinal diseases, and HIV AIDS. The earliest metabolic consequence of thiamine deficiency is a selective loss in activity of the thiamine diphosphate-dependent enzyme α-ketoglutarate dehydrogenase (α-KGDH), a rate-limiting tricarboxylic acid cycle enzyme. Thiamine deficiency is characterized neuropathologically by selective neuronal cell death in the thalamus, pons, and cerebellum. The cause of this region-selective neuronal loss is unknown, but mechanisms involving cellular energy failure, focal lactic acidosis, and NMDA receptor-mediated excitotoxicity have classically been implicated. More recently, evidence supports a role for oxidative stress. Evidence includes increased endothelial nitric oxide synthase, nitrotyrosine deposition, microglial activation, and lipid peroxidation. Reactive oxygen species production results in decreased expression of astrocytic glutamate transporters and decreased activities of α-KGDH, resulting in an amplification of cell death mechanisms in thiamine deficiency.     

Ameliorative effect of 20-OH ecdysone on streptozotocin induced oxidative stress and β-cell damage in experimental hyperglycemic rats

The present study was to evaluate the effects of 20-OH ecdysone on hyperglycemia mediated oxidative stress in streptozotocin induced diabetic rats. Diabetes was induced in experimental rats by single intraperitoneal injection of STZ (45 mg/kg b.w.) dissolved in 0.1 mol/L citrate buffer (pH 4.5). Diabetic rats exhibited increased blood glucose with significant decrease in plasma insulin levels. The activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and the levels of non-enzymic antioxidants vitamin C, vitamin E and reduced glutathione (GSH) were decreased while increases in the levels of LPO markers were observed in liver and kidney tissues of diabetic rats. Moreover, hepatic markers (aspartate aminotransferase and alanine aminotransferase) and renal markers (urea, creatinine) were significantly increased in diabetic rats as compared to control rats. Upon treatment with 20-OH ecdysone to diabetic rats showed significant ameliorative effects on all the biochemical parameters studied. Biochemical findings were supported by histological studies. These results indicated that 20-OH ecdysone exerts a protective action on pancreatic beta cell function and overcomes oxidative stress through its hypoglycemic potential. The effect produced by the 20-OH ecdysone on various parameters was comparable to that of glibenclamide – an antidiabetic drug.     

Protective effects of a chalcone derivative against Aβ-induced oxidative stress and neuronal damage

Amyloid Β-peptide (AΒ-peptide)-induced oxidative stress is thought to be a critical component of the pathophysiology of Alzheimer's disease (AD). New chalcone derivatives, the Chana series, were recently synthesized from the retrochalcones of licorice. In this study, we investigated the protective effects of the Chana series against neurodegenerative changes in vitro and in vivo. Among the Chana series, Chana 30 showed the highest free radical scavenging activity (90.7%) in the 1,1-diphenyl-2- picrylhydrazyl assay. Chana 30 also protected against AΒ-induced neural cell injury in vitro. Furthermore, Chana 30 reduced the learning and memory deficits of AΒ(1-42)-peptide injected mice. Taken together, these results suggest that Chana 30 may be a promising candidate as a potent therapeutic agent against neurodegenerative diseases. [BMB reports 2011; 44(11): 730-734].