Glucocorticoid modulates oxidative and thermogenic function of rat brown adipose tissue and human brown adipocytes.

Chronic and excessive glucocorticoid (GC) exposure can cause Cushing's syndrome, resulting in fat accumulation in selected body areas. Particularly in the brown adipose tissue (BAT), GC acts negatively, resulting in whitening of the tissue. We hypothesized that dysregulation of microRNAs by GC could be an additional mechanism to explain its negative actions in BAT. Male Wistar rats were divided into two groups: (1) Control sham and (2) GC group that was administered dexamethasone 6.25 mg/200 µL via osmotic pump implantation over 28 days. After this period, the animals were euthanized and BAT tissue was properly stored. Human fat cells treated with dexamethasone were used to translate the experimental results found in animals to human biology. GC-treated rat BAT presented with large lipid droplets, severely impaired thermogenic activation, and reduced glucose uptake measured by 18F-FDG PET/CT. GC exposure induced a reduction in the mitochondrial OXPHOS system and oxygen consumption. MicroRNA profiling of BAT revealed five top-regulated microRNAs and among them miR-21-5p was the most significantly upregulated in GC-treated rats compared to the control group. Although upregulation of miR-21-5p in the tissue, differentiated primary brown adipocytes from GC-treated rats had decreased miR-21-5p levels compared to the control group. To translate these results to the clinic, human brown adipocytes were treated with dexamethasone and miR-21-5p inhibitor. In human brown cells, inhibition of miR-21-5p increased brown adipocyte differentiation and prevented GC-induced glucose uptake, resulting in a lower glycolysis rate. In conclusion, high-dose GC therapy significantly impacts brown adipose tissue function, with a notable association between glucose uptake and miR-21-5p.

Long-term glucocorticoid infusion impairs epididymal adipocyte metabolism and maturation and affects miR-150-5p actions.

The most common form of hypercortisolism is iatrogenic Cushing's syndrome. Lipodystrophy and metabolic disorders can result from the use of exogenous glucocorticoids (GC). Adipocytes play an important role in the production of circulating exosomal microRNAs, and knockdown of Dicer promotes lipodystrophy. The aim of this study is to investigate the effect of GCs on epididymal fat and to assess their influence on circulating microRNAs associated with fat turnover. The data indicate that despite the reduction in adipocyte volume due to increased lipolysis and apoptosis, there is no difference in tissue mass, suggesting that epididymal fat pad, related to animal size, is not affected by GC treatment. Although high concentrations of GC have no direct effect on epididymal microRNA-150-5p expression, GC can induce epididymal adipocyte uptake of microRNA-150-5p, which regulates transcription factor Ppar gamma during adipocyte maturation. In addition, GC treatment increased lipolysis and decreased glucose-derived lipid and glycerol incorporation. In conclusion, the similar control and GC epididymal fat mass results from increased dense fibrogenic tissue and decreased adipocyte volume induced by the lipolytic effect of GC. These findings demonstrate the complexity of epididymal fat. They also highlight how this disease alters fat distribution. This study is the first in a series published by our laboratory showing the detailed mechanism of adipocyte turnover in this disease.

Sex-specific regulation of miR-22 and ERα in white adipose tissue of obese dam's female offspring impairs the early postnatal development of functional beige adipocytes in mice.

During inguinal adipose tissue (iWAT) ontogenesis, beige adipocytes spontaneously appear between postnatal 10 (P10) and P20 and their ablation impairs iWAT browning capacity in adulthood. Since maternal obesity has deleterious effects on offspring iWAT function, we aimed to investigate its effect in spontaneous iWAT browning in offspring. Female C57BL/6 J mice were fed a control or obesogenic diet six weeks before mating. Male and female offspring were euthanized at P10 and P20 or weaned at P21 and fed chow diet until P60. At P50, mice were treated with saline or CL316,243, a ß3-adrenoceptor agonist, for ten days. Maternal obesity induced insulin resistance at P60, and CL316,243 treatment effectively restored insulin sensitivity in male but not female offspring. This discrepancy occurred due to female offspring severe browning impairment. During development, the spontaneous iWAT browning and sympathetic nerve branching at P20 were severely impaired in female obese dam's offspring but occurred normally in males. Additionally, maternal obesity increased miR-22 expression in the iWAT of male and female offspring during development. ERα, a target and regulator of miR-22, was concomitantly upregulated in the male's iWAT. Next, we evaluated miR-22 knockout (KO) offspring at P10 and P20. The miR-22 deficiency does not affect spontaneous iWAT browning in females and, surprisingly, anticipates iWAT browning in males. In conclusion, maternal obesity impairs functional iWAT development in the offspring in a sex-specific way that seems to be driven by miR-22 levels and ERα signaling. This impacts adult browning capacity and glucose homeostasis, especially in female offspring.

Green tea actions on miRNAs expression - An update.

Compounds derived from plants have been widely studied in the context of metabolic diseases and associated clinical conditions. In this regard, although the effects of Camellia sinensis plant, from which various types of teas, such as green tea, originate, have been vastly reported in the literature, the mechanisms underlying these effects remain elusive. A deep search of the literature showed that green tea's action in different cells, tissues, and diseases is an open field in the research of microRNAs (miRNAs). miRNAs are important communicator molecules between cells in different tissues implicated in diverse cellular pathways. They have emerged as an important linkage between physiology and pathophysiology, raising the issue of polyphenols can act also by changing miRNA expression. miRNAs are short, non-coding endogenous RNA, which silence the gene functions by targeting messenger RNA (mRNA) through degradation or translation repression. Therefore, the aim of this review is to present the studies that show the main compounds of green tea modulating the expression of miRNAs in inflammation, adipose tissue, skeletal muscle, and liver. We provide an overview of a few studies that have tried to demonstrate the role of miRNAs associated with the beneficial effects of compounds from green tea. We have emphasized that there is still a considerable gap in the literature investigating the role and likely involvement of miRNAs in the extensive beneficial health effects of green tea compounds already described, indicating miRNAs as potential polyphenols' mediators with a promising field to be investigated.

Intramuscular Injection of miR-1 Reduces Insulin Resistance in Obese Mice.

The role of microRNAs in metabolic diseases has been recognized and modulation of them could be a promising strategy to treat obesity and obesity-related diseases. The major purpose of this study was to test the hypothesis that intramuscular miR-1 precursor replacement therapy could improve metabolic parameters of mice fed a high-fat diet. To this end, we first injected miR-1 precursor intramuscularly in high-fat diet-fed mice and evaluated glucose tolerance, insulin sensitivity, and adiposity. miR-1-treated mice did not lose weight but had improved insulin sensitivity measured by insulin tolerance test. Next, using an in vitro model of insulin resistance by treating C2C12 cells with palmitic acid (PA), we overexpressed miR-1 and measured p-Akt content and the transcription levels of a protein related to fatty acid oxidation. We found that miR-1 could not restore insulin sensitivity in C2C12 cells, as indicated by p-Akt levels and that miR-1 increased expression of Pgc1a and Cpt1b in PA-treated cells, suggesting a possible role of miR-1 in mitochondrial respiration. Finally, we analyzed mitochondrial oxygen consumption in primary skeletal muscle cells treated with PA and transfected with or without miR-1 mimic. PA-treated cells showed reduced basal respiration, oxygen consumption rate-linked ATP production, maximal and spare capacity, and miR-1 overexpression could prevent impairments in mitochondrial respiration. Our data suggest a role of miR-1 in systemic insulin sensitivity and a new function of miR-1 in regulating mitochondrial respiration in skeletal muscle.

Palmitic Acid Impairs Myogenesis and Alters Temporal Expression of miR-133a and miR-206 in C2C12 Myoblasts.

Palmitic acid (PA), a saturated fatty acid enriched in high-fat diet, has been implicated in the development of sarcopenic obesity. Herein, we chose two non-cytotoxic concentrations to better understand how excess PA could impact myotube formation or diameter without inducing cell death. Forty-eight hours of 100 µM PA induced a reduction of myotube diameter and increased the number of type I fibers, which was associated with increased miR-206 expression. Next, C2C12 myotube growth in the presence of PA was evaluated. Compared to control cells, 150 µM PA reduces myoblast proliferation and the expression of MyoD and miR-206 and miR-133a expression, leading to a reduced number and diameter of myotubes. PA (100 µM), despite not affecting proliferation, impairs myotube formation by reducing the expression of Myf5 and miR-206 and decreasing protein synthesis. Interestingly, 100 and 150 µM PA-treated myotubes had a higher number of type II fibers than control cells. In conclusion, PA affects negatively myotube diameter, fusion, and metabolism, which may be related to myomiRs. By providing new insights into the mechanisms by which PA affects negatively skeletal muscle, our data may help in the discovery of new targets to treat sarcopenic obesity.

Adipogenic commitment induced by green tea polyphenols remodel adipocytes to a thermogenic phenotype.

The potential contribution of green tea (GT) to the development of thermogenic/beige cells have been scarcely investigated. Here we investigated if the beneficial effects of GT in the induction of thermogenic/beige adipocytes results from an initial cell commitment during adipogenesis. Male C57Bl/6 mice (3 months) were divided into 3 groups: Control (chow diet), Obese (cafeteria diet), and Obese + GT. Mice received GT gavage (500 mg/kg of BW) over 12 weeks (5 days/week), after 4 weeks of diet, totalizing 16 weeks of experimentation. GT treatment increased energy expenditure (EE) in mice fed with cafeteria-diet leading to reduced BW gain, decreased adiposity, reduced inflammation, and improving insulin sensitivity. Those phenotypes were associated with enhanced expression of oxidative, thermogenic and beige genes. GT induced a futile cycle through de novo lipogenesis activating the thermogenic pathway. Induction of beige phenotype occurs autonomously in adipocytes and involves the PPARγ/FGF21/AMPK/UCP1 pathway. Our study identified that metabolic changes caused by GT may involve the temporal expression of PPARγ promoting the induction of thermogenic cells by reprogramming initial steps of adipocyte commitment.

Polyphenol-rich green tea extract induces thermogenesis in mice by a mechanism dependent on adiponectin signaling.

Adiponectin is downregulated in obesity negatively impacting the thermogenesis and impairing white fat browning. Despite the notable effects of green tea (GT) extract in the enhancement of thermogenesis, if its effects are being mediated by adiponectin has been scarcely explored. For this purpose, we investigated the role of adiponectin in the thermogenic actions of GT extract by using an adiponectin-knockout mice model. Male wild-type (WT) and knockout (AdipoKO) C57Bl/6 mice (3 months) were divided into 6 groups: mice fed a standard diet+gavage with water (SD WT, and SD AdipoKO), high-fat diet (HFD)+gavage with water (HFD WT, and HFD AdipoKO), and HFD + gavage with 500 mg/kg of body weight (BW) of GT extract (HFD + GT WT, and HFD + GT AdipoKO). After 20 weeks of experimentation, mice were euthanized and adipose tissue was properly removed. Our findings indicate that treatment with GT extract reversed complications of obesity in WT mice by decreasing final BW gain, adiposity index, adipocyte size and insulin resistance (IR). However, the action of the GT extract was not effective in reversing those markers in the AdipoKO mice, although GT acts independently in the reversal of IR. GT-treatment induced enhancement in energy expenditure (EE), BAT thermogenesis, and promoted browning phenotype in the subcutaneous WAT (scWAT) of WT mice. On the other hand, the thermogenic program was markedly impaired in BAT and scWAT of AdipoKO mice. Our outcomes unveiled adiponectin as a key direct signal for GT extract inducing adaptive thermogenesis and browning in scWAT.

Polyphenol-rich green tea extract improves adipose tissue metabolism by down-regulating miR-335 expression and mitigating insulin resistance and inflammation.

Obesity leads to changes in miRNA expression in adipose tissue, and this modulation is linked to the pathophysiology of the disease. Green tea (GT) is a natural source of polyphenols that have been shown to confer health benefits, particularly preventing metabolic diseases. Here, we investigated if the beneficial effects of GT in obesity results from changes in the miRNA profile in white adipose tissue. GT treatment [500 mg/body weight (BW)/12 weeks] increased energy expenditure of high-fat diet-fed mice (16 weeks), leading to reduced weight gain, decreased adiposity, reduced inflammation and improved insulin sensitivity. These phenotypes were associated with a decrease in the expression of miR-335 in the adipose tissue. miR-335 was up-regulated by TNF-α in adipocytes and, in turn, down-regulated genes involved in insulin signaling and lipid metabolism. On the other hand, GT inhibited TNF-α effect. In conclusion, miR-335 serves as a link between inflammation and impaired metabolism in adipose tissue, providing an important mechanistic insight into the molecular basis underlying GT action during obesity.

Green tea extract activates AMPK and ameliorates white adipose tissue metabolic dysfunction induced by obesity.

PURPOSE: Beneficial effects of green tea (GT) polyphenols against obesity have been reported. However, until this moment the molecular mechanisms of how green tea can modulate obesity and regulates fat metabolism, particularly in adipose tissue, remain poorly understood. The aim of this study was to evaluate the role of GT extract in the adipose tissue of obese animals and its effect on weight gain, metabolism and function (de novo lipogenesis and lipolysis), and the involvement of AMP-activated protein kinase (AMPK). METHODS AND RESULTS: Male Wistar rats were treated with GT by gavage (12 weeks/5 days/week; 500 mg/kg of body weight), and obesity was induced by cafeteria diet (8 weeks). Here, we show that obese rats treated with GT showed a significant reduction in indicators of obesity such as hyperlipidemia, fat synthesis, body weight, and fat depots as compared to those treated with standard control diet. AMPK was induced in adipose tissue in rats that were treated with GT and likely restored insulin sensitivity, increased mRNA expression of GLUT4, reducing the concentrations of plasma and liver lipid content, also stimulating fatty acid oxidation in the same tissue. Importantly, repression of de novo lipogenesis in the adipose tissue, reduced lipid droplets in the liver, and the development of insulin resistance in diet-induced obese rats were accompanied by AMPK activation. CONCLUSION: Our study identified that metabolic changes caused by GT intake induced AMPK activation and modulate the expression of genes involved in metabolism, particularly in adipose tissue, thus offering a therapeutic strategy to combat insulin resistance, dyslipidemia, and obesity in rats.

Comparative effect of fucoxanthin and vitamin C on oxidative and functional parameters of human lymphocytes.

The aim of this study was to evaluate the effects of FUCO alone or combined with vitamin C on different features of lymphocyte function related to ROS/RNS (reactive oxygen/nitrogen species) production. For this purpose we have evaluated the cytotoxicity of increasing concentrations of FUCO and vitamin C, the proliferative capacity of stimulated T- and B-lymphocytes, superoxide anion radicals (O(2)), hydrogen peroxide (H(2)O(2)) and nitric oxide (NO) production, antioxidant enzyme activities and the indexes of oxidative damage in proteins (carbonyl and thiol content). We have also evaluated the release of inflammatory cytokines and glucose-6-phosphate dehydrogenase (G6PDH) activity. Healthy human lymphocytes were acutely treated in vitro with FUCO (2 µM) with or without vitamin C (100 µM). Results revealed that human lymphocytes treated with FUCO at 2µM did not present any significant alteration in the proliferation of T- and B-lymphocytes at both resting and stimulated conditions. Moreover, FUCO used at low concentrations showed more pro-oxidant than antioxidant effects, which were recognized by the increased H(2)O(2) and increased NO production. Anti-inflammatory activity of FUCO was confirmed by significantly increased IL-10 and decreased TNF-α production. Vitamin C increased T-lymphocyte proliferation, whereas vitamin C plus FUCO promoted a reduction in the proliferation rate of these cells. All groups decreased pro-inflammatory cytokine TNF-α and increased anti-inflammatory IL-10 production although only vitamin C decreased IFN-γ either alone or when combined with FUCO. Overall, the combination of the antioxidants had more antioxidant and anti-inflammatory effects than when they were applied alone.

Oxidative stress and antioxidant status response of handball athletes: implications for sport training monitoring.

The chronic exposure to regular exercise training seems to improve antioxidant defense systems. However, the intense physical training imposed on elite athletes may lead to overtraining associated with oxidative stress. The purpose of the present study was to investigate the effect of different training loads and competition on oxidative stress, biochemical parameters and antioxidant enzymatic defense in handball athletes during 6-months of monitoring. Ten male elite handball athletes were recruited to the study. Blood samples were collected four times every six weeks throughout the season. During most intense periods of training and competitions there were significant changes in plasma indices of oxidative stress (increased TBARS and decreased thiols). Conversely, chronic adaptations to exercise training demonstrated a significant protective effect against oxidative stress in erythrocyte (decrease in TBARs and carbonyl group levels). Erythrocyte antioxidant enzyme activities were significantly increased, suggesting a training-induced antioxidant adaptation. Biomarkers of skeletal muscle damage were significantly increased during high-intensity training period (creatine kinase, lactate dehydrogenase and aspartate aminotransferase). No significant changes were observed in plasma IL-6, TNF-α and uric acid, whereas a significant reduction was found in the IL-1ß concentration and gamma-glutamyl transferase activity. Oxidative stress and antioxidant biomarkers can change throughout the season in competitive athletes, reflecting the physical stress and muscle damage that occurs as the result of competitive handball training. In addition, these biochemical measurements can be applied in the physiological follow-up of athletes.

Glycolaldehyde impairs neutrophil biochemical parameters by an oxidative and calcium-dependent mechanism--protective role of antioxidants astaxanthin and vitamin C.

AIM: The present study examined the effects of glycolaldehyde (GC) on biochemical parameters of human neutrophils and whether the antioxidant astaxanthin associated with vitamin C can modulate these parameters. METHODS: Neutrophils from healthy subjects were treated with GC (1mM) followed or not by the antioxidants astaxanthin (2 µM) and vitamin C (100 µM). We examined the phagocytic capacity, hypochlorous acid, myeloperoxidase (MPO) and glucose-6-phosphate dehydrogenase (G6PDH) activities, cytokines and [Ca(2+)](i). Also, superoxide anion, hydrogen peroxide, nitric oxide production, antioxidant enzyme activities and glutathione-recycling system were evaluated. RESULTS: GC promoted a marked reduction on the phagocytic capacity, maximal G6PDH and MPO activities, hypochlorous acid production and release of IL-1ß, IL-6 and TNF-α cytokines. Some impairment in the neutrophils biochemical parameters appears to be mediated by oxidative stress through ROS/RNS production and calcium reduction. Oxidative stress was evidenced by reduction in the activities of the main antioxidant enzymes, GSH/GSSG ratio and in the increment of O(2)(-) and H(2)O(2) and NO. CONCLUSIONS: Treatment of cells with the combination of the antioxidants astaxanthin and vitamin C was able to restore some neutrophils function mainly by decreasing ROS/RNS production and improving the redox state. Overall, our findings demonstrate that GC modulates several neutrophils biochemical parameters in vitro.

Combined astaxanthin and fish oil supplementation improves glutathione-based redox balance in rat plasma and neutrophils.

The present study aimed to investigate the effects of daily (45 days) intake of fish oil (FO; 10mg EPA/kg body weight (BW) and 7 mg DHA/kg BW) and/or natural ASTA (1mg ASTA/kg BW) on oxidative stress and functional indexes of neutrophils isolated from Wistar rats by monitoring superoxide (O(2)(-)), hydrogen peroxide (H(2)O(2)), and nitric oxide (NO()) production compared to the progression of auto-induced lipid peroxidation and Ca(2+) release in activated neutrophils. Furthermore, phagocytic capacity, antioxidant enzyme activities, glutathione-recycling system, and biomarkers of lipid and protein oxidation in neutrophils were compared to the redox status. Our results show evidence of the beneficial effects of FO+ASTA supplementation for immune competence based on the redox balance in plasma (significant increase in GSH-dependent reducing power), non-activated neutrophils (increased activity of the glutathione-recycling enzymes GPx and GR) and PMA-activated neutrophils (lower O(2)(-), H(2)O(2), and NO() generation, reduced membrane oxidation, but higher phagocytic activity). Combined application of ASTA and FO promoted hypolipidemic/hypocholesterolemic effects in plasma and resulted in increased phagocytic activity of activated neutrophils when compared with ASTA or FO applied alone. In PMA-activated neutrophils, ASTA was superior to FO in exerting antioxidant effects. The bulk of data reinforces the hypothesis that habitual consumption of marine fish (e.g. salmon, which is a natural source of both astaxanthin and fish oil) is beneficial to human health, in particular by improving immune response and lowering the risk of vascular and infectious diseases.

Combined fish oil and astaxanthin supplementation modulates rat lymphocyte function.

PURPOSE: Higher intakes of n-3 polyunsaturated fatty acids that are abundant in marine fishes have been long described as a "good nutritional intervention" with increasing clinical benefits to cardiovascular health, inflammation, mental, and neurodegenerative diseases. The present study was designed to investigate the effect of daily fish oil (FO-10 mg EPA/kg body weight (BW) and 7 mg DHA/kg BW) intake by oral gavage associated with the antioxidant astaxanthin (ASTA-1 mg/kg BW) on the redox metabolism and the functional properties of lymphocytes from rat lymph nodes. METHODS: This study was conducted by measurements of lymphocyte proliferation capacity, ROS production [superoxide (O2(•-)) and hydrogen peroxide (H2O2)], nitric oxide (NO(•)) generation, intracellular calcium release, oxidative damage to lipids and proteins, activities of major antioxidant enzymes, GSH/GSSG content, and cytokines release. RESULTS: After 45 days of FO + ASTA supplementation, the proliferation capacity of activated T- and B-lymphocytes was significantly diminished followed by lower levels of O2(•-), H2O2 and NO(•) production, and increased activities of total/SOD, GR and GPx, and calcium release in cytosol. ASTA was able to prevent oxidative modification in cell structures through the suppression of the oxidative stress condition imposed by FO. L: -selectin was increased by FO, and IL-1ß was decreased only by ASTA supplementation. CONCLUSION: We can propose that association of ASTA with FO could be a good strategy to prevent oxidative stress induced by polyunsaturated fatty acids and also to potentiate immuno-modulatory effects of FO.

Cytokines and oxidative stress status following a handball game in elite male players.

BACKGROUND: Handball is considered an intermittent sport that places an important stress on a player's aerobic and anaerobic metabolism. However, the oxidative stress responses following a handball game remain unknown. We investigated the responses of plasma and erythrocyte antioxidant system and oxidative stress biomarkers following a single handball game. METHODS: Fourteen male elite Brazilian handball athletes were recruited in the present study. Blood samples were taken before, immediately, and 24 hours after the game. RESULTS: After the game and during 24 hours of recovery, the concentration of all oxidative stress indices changed significantly in a way indicating increased oxidative stress in the blood (thiol groups and reduced glutathione decreased, whereas TBARS and plasma antioxidant capacity was increased) as well as in erythrocyte (increased levels of TBARS and protein carbonyls). Erythrocyte antioxidant enzyme activities were also significantly changed by handball. Muscle damage indices (creatine kinase and lactate dehydrogenase) increased significantly after exercise. In addition, IL-6 increased after the game, whereas TNF-α decreased during recovery. CONCLUSION: This study demonstrates that a single handball game in elite athletes induces a marked state of oxidative stress evidenced by the oxidative modification in plasma and erythrocyte macromolecules, as well as by changes in the enzymatic and nonenzymatic antioxidant system.

ROS production in neutrophils from alloxan-induced diabetic rats treated in vivo with astaxanthin.

BACKGROUND: Astaxanthin (ASTA) is a carotenoid which has powerful antioxidant, anti-tumor, anti-diabetic, anti-inflammatory and cardioprotective properties. The present study investigated the effect of daily ASTA intake on oxidative stress and the functional properties of neutrophils from alloxan-induced diabetic rats. METHODS: Neutrophils isolated from ASTA-fed rats (30days, 20mg ASTA/kg of body weight - BW) induced to diabetes by alloxan treatment (i.p. 75mg/BW) were assessed by: production of superoxide and hydrogen peroxide, nitric oxide, basal calcium release, oxidative damage (TBARS and carbonyls content), and activities of major antioxidant enzymes. RESULTS: Our results show that diabetes promotes a significant oxidative stress in neutrophils. The production of superoxide was significantly increased in neutrophils from diabetic rats and treatment with ASTA was not effective in reducing superoxide levels. At the same time, a reduction in the activity of total superoxide dismutase enzyme was observed, which was not restored after treatment with ASTA. At resting conditions, neutrophils have a higher basal production of hydrogen peroxide, which is enhanced following PMA-stimulation. Treatment with ASTA does not restore values to the basal levels. The indicators of oxidative damage to biomolecules showed that diabetic rats significantly increased the lipid and protein damage, but this change was reversed after treatment with ASTA. CONCLUSION: Our results show that diabetes condition promotes a marked oxidative stress in neutrophils and treatment with ASTA for 30days at a dose of 20mg/kg of BW partially reverses those deleterious effects.

ROS production in neutrophils from alloxan-induced diabetic rats treated in vivo with astaxanthin

Astaxanthin (ASTA) is a carotenoid which has powerful antioxidant, anti-tumor, anti-diabetic, anti-inflammatory and cardioprotective properties. The present study investigated the effect of daily ASTA intake on oxidative stress and the functional properties of neutrophils from alloxan-induced diabetic rats.Neutrophils isolated from ASTA-fed rats (30 days, 20 mg ASTA/kg of body weight — BW) induced to diabetes by alloxan treatment (i.p. 75 mg/BW) were assessed by: production of superoxide and hydrogen peroxide, nitric oxide, basal calcium release, oxidative damage (TBARS and carbonyls content), and activities of major antioxidant enzymes.Our results show that diabetes promotes a significant oxidative stress in neutrophils. The production of superoxide was significantly increased in neutrophils from diabetic rats and treatment with ASTA was not effective in reducing superoxide levels. At the same time, a reduction in the activity of total superoxide dismutase enzyme was observed, which was not restored after treatment with ASTA. At resting conditions, neutrophils have a higher basal production of hydrogen peroxide, which is enhanced following PMAstimulation. Treatment with ASTA does not restore values to the basal levels. The indicators of oxidative damage to biomolecules showed that diabetic rats significantly increased the lipid and protein damage, but this change was reversed after treatment with ASTA. Our results show that diabetes condition promotes a marked oxidative stress in neutrophils and treatment with ASTA for 30 days at a dose of 20 mg/kg of BW partially reverses those deleterious effects.

Testosterone suppresses oxidative stress in human neutrophils.

The in vitro effect of testosterone on human neutrophil function was investigated. Blood neutrophils from healthy male subjects were isolated and treated with 10 nM, 0.1 and 10 microM testosterone for 24 h. As compared with untreated cells, the testosterone treatment produced a significant decrease of superoxide production as indicated by the measurement of extra- and intracellular superoxide content. An increment in the production of nitric oxide was observed at 0.1 and 10 microM testosterone concentrations, whereas no effect was found for 10 nM. Intracellular calcium mobilization was significantly increased at 10 nM, whereas it was reduced at 10 microM testosterone. There was an increase in phagocytic capacity at 10 nM and a decrease of microbicidal activity in neutrophils treated with testosterone at 10 microM. Glutathione reductase activity was increased by testosterone treatment, whereas no effect was observed in other antioxidant enzyme activities. An increase in the content of thiol groups was observed at all testosterone concentrations. Lipid peroxidation in neutrophils evaluated by levels of TBARS was decreased at 10 nM and 0.1 microM testosterone. These results indicate the antioxidant properties of testosterone in neutrophils as suggested by reduction of superoxide anion production, and lipid peroxidation, and by the increase in nitric oxide production, glutathione reductase activity and the content of thiol groups. Therefore, the plasma levels of testosterone are important regulators of neutrophil function and so of the inflammatory response.

Astaxanthin ameliorates the redox imbalance in lymphocytes of experimental diabetic rats.

Diabetes mellitus is a syndrome of impaired insulin secretion/sensitivity and frequently diagnosed by hyperglycemia, lipid abnormalities, and vascular complications. The diabetic 'glucolipotoxicity' also induces immunodepression in patients by redox impairment of immune cells. Astaxanthin (ASTA) is a pinkish-orange carotenoid found in many marine foods (e.g. shrimp, crabs, salmon), which has powerful antioxidant, photoprotective, antitumor, and cardioprotective properties. Aiming for an antioxidant therapy against diabetic immunodepression, we here tested the ability of prophylactic ASTA supplementation (30 days, 20 mg ASTA/kg BW) to oppose the redox impairment observed in isolated lymphocytes from alloxan-induced diabetic Wistar rats. The redox status of lymphocytes were thoroughly screened by measuring: (i) production of superoxide (O(2)(-)), nitric oxide (NO), and hydrogen peroxide (H(2)O(2)); (ii) cytosolic Ca(2+); (iii) indexes of oxidative injury; and (iv) activities of major antioxidant enzymes. Hypolipidemic and antioxidant effects of ASTA in plasma of ASTA-fed/diabetic rats were apparently reflected in the circulating lymphocytes, since lower activities of catalase, restored ratio between glutathione peroxidase and glutathione reductase activities and lower scores of lipid oxidation were concomitantly measured in those immune cells. Noteworthy, lower production of NO and O(2)(-) (precursors of peroxynitrite), and lower cytosolic Ca(2+) indicate a hypothetical antiapoptotic effect of ASTA in diabetic lymphocytes. However, questions are still open regarding the proper ASTA supplementation dose needed to balance efficient antioxidant protection and essential NO/H(2)O(2)-mediated proliferative capacities of diabetic lymphocytes.