Sulforaphane prevents diabetes-induced hepatic ferroptosis by activating Nrf2 signaling axis.

Recently, we characterized the ferroptotic phenotype in the liver of diabetic mice and revealed nuclear factor (erythroid-derived-2)-related factor 2 (Nrf2) inactivation as an integral part of hepatic injury. Here, we aim to investigate whether sulforaphane, an Nrf2 activator and antioxidant, prevents diabetes-induced hepatic ferroptosis and the mechanisms involved. Male C57BL/6 mice were divided into four groups: control (vehicle-treated), diabetic (streptozotocin-induced; 40 mg/kg, from Days 1 to 5), diabetic sulforaphane-treated (2.5 mg/kg from Days 1 to 42) and non-diabetic sulforaphane-treated group (2.5 mg/kg from Days 1 to 42). Results showed that diabetes-induced inactivation of Nrf2 and decreased expression of its downstream antiferroptotic molecules critical for antioxidative defense (catalase, superoxide dismutases, thioredoxin reductase), iron metabolism (ferritin heavy chain (FTH1), ferroportin 1), glutathione (GSH) synthesis (cystine-glutamate antiporter system, cystathionase, glutamate-cysteine ligase catalitic subunit, glutamate-cysteine ligase modifier subunit, glutathione synthetase), and GSH recycling - glutathione reductase (GR) were reversed/increased by sulforaphane treatment. In addition, we found that the ferroptotic phenotype in diabetic liver is associated with increased ferritinophagy and decreased FTH1 immunopositivity. The antiferroptotic effect of sulforaphane was further evidenced through the increased level of GSH, decreased accumulation of labile iron and lipid peroxides (4-hydroxy-2-nonenal, lipofuscin), decreased ferritinophagy and liver damage (decreased fibrosis, alanine aminotransferase, and aspartate aminotransferase). Finally, diabetes-induced increase in serum glucose and triglyceride level was significantly reduced by sulforaphane. Regardless of the fact that this study is limited by the use of one model of experimentally induced diabetes, the results obtained demonstrate for the first time that sulforaphane prevents diabetes-induced hepatic ferroptosis in vivo through the activation of Nrf2 signaling pathways. This nominates sulforaphane as a promising phytopharmaceutical for the prevention/alleviation of ferroptosis in diabetes-related pathologies.

Defining the ferroptotic phenotype of beta cells in type 1 diabetes and its inhibition as a potential antidiabetic strategy.

Introduction: Recently, the involvement of ferroptotic cell death in the reduction of ß-cell mass in diabetes has been demonstrated. To elucidate the mechanisms of ß-cell ferroptosis and potential antidiabetic effects of the ferroptosis inhibitor ferrostatin-1 (Fer-1) in vivo, a mouse model of type 1 diabetes (T1D) was used. Methods: Animals were divided into three groups: control (vehicle-treated), diabetic (streptozotocin-treated, 40 mg/kg, from days 1-5), and diabetic treated with Fer-1 (1 mg/kg, from days 1-21). On day 22, glycemia and insulinemia were measured and pancreases were isolated for microscopic analyses. Results: Diabetes disturbed general parameters of ß-cell mass (islet size, ß-cell abundance and distribution) and health (insulin and PDX-1 expression), increased lipid peroxidation in islet cells, and phagocytic removal of iron-containing material. It also downregulated the main players of the antiferroptotic pathway - Nrf2, GPX4, and xCT. In contrast, Fer-1 ameliorated the signs of deterioration of ß-cell/islets, decreased lipid peroxidation, and reduced phagocytic activity, while upregulated expression of Nrf2 (and its nuclear translocation), GPX4, and xCT in ß-cell/islets. Discussion: Overall, our study confirms ferroptosis as an important mode of ß-cell death in T1D and suggests antiferroptotic agents as a promising strategy for the prevention and treatment of diabetes.

Involvement of Ferroptosis in Diabetes-Induced Liver Pathology.

Cell death plays an important role in diabetes-induced liver dysfunction. Ferroptosis is a newly defined regulated cell death caused by iron-dependent lipid peroxidation. Our previous studies have shown that high glucose and streptozotocin (STZ) cause ß-cell death through ferroptosis and that ferrostatin-1 (Fer-1), an inhibitor of ferroptosis, improves ß-cell viability, islet morphology, and function. This study was aimed to examine in vivo the involvement of ferroptosis in diabetes-related pathological changes in the liver. For this purpose, male C57BL/6 mice, in which diabetes was induced with STZ (40 mg/kg/5 consecutive days), were treated with Fer-1 (1 mg/kg, from day 1-21 day). It was found that in diabetic mice Fer-1 improved serum levels of ALT and triglycerides and decreased liver fibrosis, hepatocytes size, and binucleation. This improvement was due to the Fer-1-induced attenuation of ferroptotic events in the liver of diabetic mice, such as accumulation of pro-oxidative parameters (iron, lipofuscin, 4-HNE), decrease in expression level/activity of antioxidative defense-related molecules (GPX4, Nrf2, xCT, GSH, GCL, HO-1, SOD), and HMGB1 translocation from nucleus into cytosol. We concluded that ferroptosis contributes to diabetes-related pathological changes in the liver and that the targeting of ferroptosis represents a promising approach in the management of diabetes-induced liver injury.

Ferroptosis as a Novel Determinant of ß-Cell Death in Diabetic Conditions.

The main pathological hallmark of diabetes is the loss of functional ß-cells. Among several types of ß-cell death in diabetes, the involvement of ferroptosis remains elusive. Therefore, we investigated the potential of diabetes-mimicking factors: high glucose (HG), proinflammatory cytokines, hydrogen peroxide (H2O2), or diabetogenic agent streptozotocin (STZ) to induce ferroptosis of ß-cells in vitro. Furthermore, we tested the contribution of ferroptosis to injury of pancreatic islets in an STZ-induced in vivo diabetic model. All in vitro treatments increased loss of Rin-5F cells along with the accumulation of reactive oxygen species, lipid peroxides and iron, inactivation of NF-E2-related factor 2 (Nrf2), and decrease in glutathione peroxidase 4 expression and mitochondrial membrane potential (MMP). Ferrostatin 1 (Fer-1), ferroptosis inhibitor, diminished the above-stated effects and rescued cells from death in case of HG, STZ, and H2O2 treatments, while failed to increase MMP and to attenuate cell death after the cytokines' treatment. Moreover, Fer-1 protected pancreatic islets from STZ-induced injury in diabetic in vivo model, since it decreased infiltration of macrophages and accumulation of lipid peroxides and increased the population of insulin-positive cells. Such results revealed differences between diabetogenic stimuli in determining the destiny of ß-cells, emerging HG, H2O2, and STZ, but not cytokines, as contributing factors to ferroptosis and shed new light on an antidiabetic strategy based on Nrf2 activation. Thus, targeting ferroptosis in diabetes might be a promising new approach for preservation of the ß-cell population. Our results obtained from in vivo study strongly justify this approach.

Adipokine signatures of subcutaneous and visceral abdominal fat in normal-weight and obese women with different metabolic profiles.

INTRODUCTION: Metabolic syndrome arises from abnormal adipose function accompanied by insulin resistance. As early factors reflecting/impacting lipid storage dysfunction of adipose tissues, we sought to determine adipokine levels in subcutaneous and visceral adipose tissues (SAT and VAT). MATERIAL AND METHODS: Gene and protein expression levels of leptin, adiponectin, and resistin were analysed in SAT and VAT of normal-weight and overweight/obese women, subclassified according to insulin resistance index, triglyceride, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels into metabolically healthy and "at risk" groups. RESULTS: Compared with normal-weight women, obese women had higher serum leptin levels (p < 0.05), as well as increased leptin gene and protein expression in VAT. Conversely, expression levels of leptin were lower in SAT of obese women, and minor in the SAT of "at risk" groups of women, compared with weight-matched healthy groups. In addition, lower adiponectin levels were detected in SAT of metabolically healthy obese women (p < 0.01), and lower in SAT and VAT (p < 0.05) of "at risk" obese women compared to healthy, obese women. Significant differences in resistin levels were only observed in obese women; resistin gene expression was higher in VAT and SAT of obese, compared to normal-weight women. However, higher gene expression was not consistent with protein expression of resistin. CONCLUSIONS: Low adiponectin in both examined adipose tissues and inappropriate leptin expression levels in SAT appear to be important characteristics of obesity-related metabolic syndrome. Intriguingly, this adipokine dysregulation is primary seen in SAT, suggesting that endocrine dysfunction in this abdominal depot may be an early risk sign of metabolic syndrome.

Reactive oxygen, nitrogen, and sulfur species in human male fertility. A crossroad of cellular signaling and pathology.

Infertility is a significant global health problem that currently affects one of six couples in reproductive age. The quality of male reproductive cells dramatically decreased over the last years and almost every aspect of modern life additionally worsen sperm functional parameters that consequently markedly increase male infertility. This clearly points out the importance of finding a new approach to treat male infertility. Redox signaling mediated by reactive oxygen, nitrogen and sulfur species (ROS, RNS, and RSS respectively), has appeared important for sperm reproductive function. Present review summarizes the current knowledge of ROS, RNS, and RSS in male reproductive biology and identifies potential targets for development of novel pharmacological and therapeutic approaches for male infertility by targeted therapeutic modulation of redox signaling.

Evaluation of the antioxidative enzymes in the seminal plasma of infertile men: Contribution to classic semen quality analysis.

Protein expression/activity of antioxidative defense enzymes (AD) in seminal plasma of fertile men might be used as biomarkers of male fertility status. To test this concept, the present study examined the semen parameters of males among 14 normal idiopathic (normozoospermia) and 84 subnormal (teratozoospermia, oligoteratozoospermia, oligoasthenoteratozoospermia) infertile individuals\. We investigated levels of protein expression/activity of Cu, Zn superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD), catalase and glutathione peroxidase (GSH-Px), their association with functional sperm parameters, as well as their potential to serve as biomarkers of specific sperm pathologies. Although the activity of CuZnSOD and protein expression of catalase were significantly correlated with several sperm parameters, underlying their potential role in etiology of various sperm abnormalities, investigation of their potential usefulness as a biomarker of semen quality showed that these AD enzymes could not distinguish subtle differences between various sperm pathologies. In contrast, GSH-Px activity was decreased in all groups with sperm pathologies and was a very good indicator of aberrations in functional sperm parameters, explaining up to 94.6% of infertility cases where functional sperm parameters were affected. Therefore, assessment of GSH-Px activity showed the potential to discriminate between infertile males with normal and subnormal semen characteristics and may prove useful in the evaluation of male (in)fertility. Abbreviations: AD: antioxidative defense; Cu, Zn SOD: copper, zinc superoxide dismutase; GSH-Px: glutathione peroxidase; MnSOD: manganese superoxide dismutase; NS: normospermia; OATS: oligoasthenoteratozoospermia; OTS: oligoteratozoospermia; ROC: receiver operating characteristic; ROS: reactive oxygen species; TS: teratozoospermia; WHO: world health organization.

Level of NO/nitrite and 3-nitrotyrosine in seminal plasma of infertile men: Correlation with sperm number, motility and morphology.

Nitric oxide (NO) is a signaling molecule responsible for initiation of molecular events that influence sperm functionality in a concentration-dependent manner. It is still not fully understood how seminal plasma NO contributes to sperm pathologies. The aim of this study was to elucidate whether and how NO is implicated in etiology of different sperm abnormalities. To this end we determine NO, nitrite and 3-nitrotyrosine (3-NT) content in seminal plasma of infertile men with specific pathologies (terato-, oligoterato- and oligoasthenoteratospermia) and relate it to infertile normospermic samples. To gain further understanding of NO metabolism in seminal plasma we determine protein expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS). Here we show that NO, nitrite and 3-NT levels in seminal plasma of men with suboptimal semen parameters are significantly lower compared to normospermic men. An increase in protein expression of eNOS and no change in protein expression of iNOS is observed in men with sperm pathologies. Association of seminal plasma 3-NT level with functional sperm parameters is observed - positive correlation with sperm count, motility and morphology in normospermia, teratospermia and oligoteratospermia, as well as negative correlation with sperm morphology and motility in oligoasthenoteratospermia. Present study revealed that suboptimal seminal plasma NO content is found in all examined sperm pathologies. This result unequivocally shows the importance of NO for sperm function and involvement of suboptimal NO level in etiology of sperm abnormalities. Lower seminal plasma 3-NT level and its significant association with sperm parameters, found in pathologies, strongly indicates that protein nitration is important for spermatozoa function and that failure to establish this post-translational protein modification might be involved in etiology of sperm abnormalities. According to our results, NO measurement can discriminate infertile men with sperm pathologies from infertile normospermic men but is not indicative of a specific type of sperm pathology.

Structural alterations in rat myocardium induced by chronic l-arginine and l-NAME supplementation.

Structural changes affecting cardiomyocyte function may contribute to the pathophysiological remodeling underlying cardiac function impairment. Recent reports have shown that endogenous nitric oxide (NO) plays an important role in this process. In order to examine the role of NO in cardiomyocyte remodeling, male rats were acclimated to room temperature (22 ± 1 °C) or cold (4 ± 1 °C) and treated with 2.25% l-arginine·HCl or 0.01% l-NAME (Nω-nitro-l-arginine methyl ester)·HCl for 45 days. Untreated groups served as controls. Right heart ventricles were routinely prepared for light microscopic examination. Stereological estimations of volume densities of cardiomyocytes, surrounding blood vessels and connective tissue, as well as the morphometric measurements of cardiomyocyte diameters were performed. Tissue sections were also analyzed for structural alterations. We observed that both l-arginine and l-NAME supplementation induced cardiomyocyte hypertrophy, regardless of ambient temperature. However, cardiomyocyte hypertrophy was associated with fibrosis and extra collagen deposition only in the l-NAME treated group. Taken together, our results suggest that NO has a modulatory role in right heart ventricle remodeling by coordinating hypertrophy of cardiomyocytes and fibrous tissue preventing cardiac fibrosis.

A lesson from the oxidative metabolism of hibernator heart: Possible strategy for cardioprotection.

In the present study we hypothesized that myocardial adaptive phenotype in mammalian hibernation involves rearrangement of mitochondria bioenergetic pathways providing protective pattern in states of reduced metabolism and low temperature. European ground squirrels (Spermophilus citellus) were exposed to low temperature (4 ±â€¯1 °C) and then divided into two groups: (1) animals that fell into torpor (hibernating group) and (2) animals that stayed active and euthermic for 1, 3, 7, 12, or 21 days (cold-exposed group). Protein levels of selected components of the electron transport chain and ATP synthase in the heart increased after prolonged cold acclimation (mainly from day 7-21 of cold exposure) and during hibernation. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was also upregulated under both cold exposure and hibernating conditions. The phosphorylation state (Thr172) of 5'-AMP-activated protein kinase α increased early in cold exposure (at day 1 and 3) along with increased protein levels of phosphofructokinase and pyruvate dehydrogenase, whereas hypoxia inducible factor 1α protein levels showed no changes in response to cold exposure or hibernation. Hibernation also resulted in protein upregulation of three antioxidant defense enzymes (manganese and copper/zinc superoxide dismutases and glutathione peroxidase) and thioredoxin in the heart. Cold-exposed and hibernation-related phenotypes of the heart are characterized by improved molecular basis for mitochondrial energy-producing and antioxidant capacities that are achieved in a controlled manner. The recapitulation of such adaptive mechanisms found in hibernators could have broad application for myocardial protection from ishemia/reperfusion to improve hypothermic survival and cold preservation of hearts from non-hibernating species, including humans.

The role of nitric oxide in diabetic skin (patho)physiology.

The role of nitric oxide (NO) in cutaneous physiology/pathology became a growing research field since the discovery that almost all types of skin cells can synthetize this redox signaling molecule about 20 years ago. Now, it is evident that NO is an important player in skin physiological processes and in responses of cutaneous cells to external insults, while the impaired NO signaling has an important consequence in skin pathology. Skin disorders are common complications in diabetic conditions. Various metabolic/biochemical and immunological dysregulations in diabetic skin are tightly coupled with the disturbances in the redox state, primarily the ratio between NO and superoxide (О2-). This review describes possible therapeutic significance of different redox state modulators in the treatment of diabetic skin disorders. The focus is on those modulators that tightly control NO/О2- ratio through the complex mechanisms affecting endogenous NO and О2- producing and removing systems. The fact that classic antioxidants failed to show significant benefits in diabetes, emphasizes the importance of such redox mechanism-based and targeted approaches.

Physiological regulation and metabolic role of browning in white adipose tissue.

Great progress has been made in our understanding of the browning process in white adipose tissue (WAT) in rodents. The recognition that i) adult humans have physiologically inducible brown adipose tissue (BAT) that may facilitate resistance to obesity and ii) that adult human BAT molecularly and functionally resembles beige adipose tissue in rodents, reignited optimism that obesity and obesity-related diabetes type 2 can be battled by controlling the browning of WAT. In this review the main cellular mechanisms and molecular mediators of browning of WAT in different physiological states are summarized. The relevance of browning of WAT in metabolic health is considered primarily through a modulation of biological role of fat tissue in overall metabolic homeostasis.

Early energy metabolism-related molecular events in skeletal muscle of diabetic rats: The effects of l-arginine and SOD mimic.

Considering the vital role of skeletal muscle in control of whole-body metabolism and the severity of long-term diabetic complications, we aimed to reveal the molecular pattern of early diabetes-related skeletal muscle phenotype in terms of energy metabolism, focusing on regulatory mechanisms, and the possibility to improve it using two redox modulators, l-arginine and superoxide dismutase (SOD) mimic. Alloxan-induced diabetic rats (120 mg/kg) were treated with l-arginine or the highly specific SOD mimic, M40403, for 7 days. As appropriate controls, non-diabetic rats received the same treatments. We found that l-arginine and M40403 restored diabetes-induced impairment of phospho-5'-AMP-activated protein kinase α (AMPKα) signaling by upregulating AMPKα protein itself and its downstream effectors, peroxisome proliferator-activated receptor-γ coactivator-1α and nuclear respiratory factor 1. Also, there was a restitution of the protein levels of oxidative phosphorylation components (complex I, complex II and complex IV) and mitofusin 2. Furthermore, l-arginine and M40403 induced translocation of glucose transporter 4 to the membrane and upregulation of protein of phosphofructokinase and acyl coenzyme A dehydrogenase, diminishing negative diabetic effects on limiting factors of glucose and lipid metabolism. Both treatments abolished diabetes-induced downregulation of sarcoplasmic reticulum calcium-ATPase proteins (SERCA 1 and 2). Similar effects of l-arginine and SOD mimic treatments suggest that disturbances in the superoxide/nitric oxide ratio may be responsible for skeletal muscle mitochondrial and metabolic impairment in early diabetes. Our results provide evidence that l-arginine and SOD mimics have potential in preventing and treating metabolic disturbances accompanying this widespread metabolic disease.

Targeting the NO/superoxide ratio in adipose tissue: relevance to obesity and diabetes management.

Insulin sensitivity and metabolic homeostasis depend on the capacity of adipose tissue to take up and utilize excess glucose and fatty acids. The key aspects that determine the fuel-buffering capacity of adipose tissue depend on the physiological levels of the small redox molecule, nitric oxide (NO). In addition to impairment of NO synthesis, excessive formation of the superoxide anion (О2•- ) in adipose tissue may be an important interfering factor diverting the signalling of NO and other reactive oxygen and nitrogen species in obesity, resulting in metabolic dysfunction of adipose tissue over time. Besides its role in relief from superoxide burst, enhanced NO signalling may be responsible for the therapeutic benefits of different superoxide dismutase mimetics, in obesity and experimental diabetes models. This review summarizes the role of NO in adipose tissue and highlights the effects of NO/О2•- ratio 'teetering' as a promising pharmacological target in the metabolic syndrome. LINKED ARTICLES: This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Targeting the superoxide/nitric oxide ratio by L-arginine and SOD mimic in diabetic rat skin.

Setting the correct ratio of superoxide anion (O2•-) and nitric oxide (•NO) radicals seems to be crucial in restoring disrupted redox signaling in diabetic skin and improvement of •NO physiological action for prevention and treatment of skin injuries in diabetes. In this study we examined the effects of L-arginine and manganese(II)-pentaazamacrocyclic superoxide dismutase (SOD) mimic - M40403 in diabetic rat skin. Following induction of diabetes by alloxan (blood glucose level ≥12 mMol l -1) non-diabetic and diabetic male Mill Hill hybrid hooded rats were divided into three subgroups: (i) control, and receiving: (ii) L-arginine, (iii) M40403. Treatment of diabetic animals started after diabetes induction and lasted for 7 days. Compared to control, lower cutaneous immuno-expression of endothelial NO synthase (eNOS), heme oxygenase 1 (HO1), manganese SOD (MnSOD) and glutathione peroxidase (GSH-Px), in parallel with increased NFE2-related factor 2 (Nrf2) and nitrotyrosine levels characterized diabetic skin. L-arginine and M40403 treatments normalized alloxan-induced increase in nitrotyrosine. This was accompanied by the improvement/restitution of eNOS and HO1 or MnSOD and GSH-Px protein expression levels in diabetic skin following L-arginine, i.e. SOD mimic treatments, respectively. The results indicate that L-arginine and M40403 stabilize redox balance in diabetic skin and suggest the underlying molecular mechanisms. Restitution of skin redox balance by L-arginine and M40403 may represent an effective strategy to ameliorate therapy of diabetic skin.

Expression patterns of mitochondrial OXPHOS components, mitofusin 1 and dynamin-related protein 1 are associated with human embryo fragmentation.

Developmental dysfunction in embryos, such as a lethal level of fragmentation, is assumed to be mitochondrial in origin. This study investigated the molecular basis of mitochondrial impairment in embryo fragmentation. Transcription patterns of factors that determine mitochondrial functionality: (i) components of the oxidative phosphorylation (OXPHOS) - complex I, cytochrome b, complex IV and ATP synthase; (ii) mitochondrial membrane potential (MMP); (iii) mitochondrial DNA (mtDNA) content and (iv) proteins involved in mitochondrial dynamics, mitofusin 1 (Mfn1) and dynamin related protein 1 (Drp1) were examined in six-cells Day 3 non-fragmented (control), low-fragmented (LF) and high-fragmented (HF) human embryos. Gene expression of mitochondria-encoded components of complex I and IV, cytochrome b and mtDNA were increased in HF embryos compared with control and LF embryos. In LF embryos, expression of these molecules was decreased compared with control and HF embryos. Both classes of fragmented embryos had decreased MMP compared with control. LF embryos had increased gene expression of Mfn1 accompanied by decreased expression of Drp1, while HF embryos had decreased Mfn1 expression but increased Drp1 expression. The study revealed that each improper transcriptional (in)activation of mitochondria-encoded components of the OXPHOS during early in vitro embryo development is associated with a decrease in MMP and with embryo fragmentation. The results also showed the importance of mitochondrial dynamics in fragmentation, at least in the extent of this process.

Redox implications in adipose tissue (dys)function--A new look at old acquaintances.

Obesity is an energy balance disorder associated with dyslipidemia, insulin resistance and diabetes type 2, also summarized with the term metabolic syndrome or syndrome X. Increasing evidence points to "adipocyte dysfunction", rather than fat mass accretion per se, as the key pathophysiological factor for metabolic complications in obesity. The dysfunctional fat tissue in obesity characterizes a failure to safely store metabolic substrates into existing hypertrophied adipocytes and/or into new preadipocytes recruited for differentiation. In this review we briefly summarize the potential of redox imbalance in fat tissue as an instigator of adipocyte dysfunction in obesity. We reveal the challenge of the adipose redox changes, insights in the regulation of healthy expansion of adipose tissue and its reduction, leading to glucose and lipids overflow.

Two key temporally distinguishable molecular and cellular components of white adipose tissue browning during cold acclimation.

KEY POINTS: White to brown adipose tissue conversion and thermogenesis can be ignited by different conditions or agents and its sustainability over the long term is still unclear. Browning of rat retroperitoneal white adipose tissue (rpWAT) during cold acclimation involves two temporally apparent components: (1) a predominant non-selective browning of most adipocytes and an initial sharp but transient induction of uncoupling protein 1, peroxisome proliferator-activated receptor (PPAR) coactivator-1α, PPARγ and PPARα expression, and (2) the subsistence of relatively few thermogenically competent adipocytes after 45 days of cold acclimation. The different behaviours of two rpWAT beige/brown adipocyte subsets control temporal aspects of the browning process, and thus regulation of both components may influence body weight and the potential successfulness of anti-obesity therapies. ABSTRACT: Conversion of white into brown adipose tissue may have important implications in obesity resistance and treatment. Several browning agents or conditions ignite thermogenesis in white adipose tissue (WAT). To reveal the capacity of WAT to function in a brownish/burning mode over the long term, we investigated the progression of the rat retroperitoneal WAT (rpWAT) browning during 45 days of cold acclimation. During the early stages of cold acclimation, the majority of rpWAT adipocytes underwent multilocularization and thermogenic-profile induction, as demonstrated by the presence of a multitude of uncoupling protein 1 (UCP1)-immunopositive paucilocular adipocytes containing peroxisome proliferator-activated receptor (PPAR) coactivator-1α (PGC-1α) and PR domain-containing 16 (PRDM16) in their nuclei. After 45 days, all adipocytes remained PRDM16 immunopositive, but only a few multilocular adipocytes rich in mitochondria remained UCP1/PGC-1α immunopositive. Molecular evidence showed that thermogenic recruitment of rpWAT occurred following cold exposure, but returned to starting levels after cold acclimation. Compared with controls (22 ± 1 °C), levels of UCP1 mRNA increased in parallel with PPARγ (PPARα from days 1 to 7 and PGC-1α on day 1). Transcriptional recruitment of rpWAT was followed by an increase in UCP1 protein content (from days 1 to 21). Results clearly showed that most of the adipocytes within rpWAT underwent transient brown-fat-like thermogenic recruitment upon stimulation, but only a minority of cells retained a brown adipose tissue-like phenotype after the attainment of cold acclimation. Therefore, browning of WAT is dependent on both maintaining the thermogenic response and retaining enough brown-like thermogenically competent adipocytes in the long-term. Both aspects of browning could be important for long-term energy homeostasis and body-weight regulation.

Correlation between sperm parameters and protein expression of antioxidative defense enzymes in seminal plasma: a pilot study.

BACKGROUND: Semen analysis is the cornerstone in the evaluation of male (in)fertility. However, there are men with normal semen tests but with impaired fertilizing ability, as well as fertile men with poor sperm characteristics. Thus, there is rising interest to find novel parameters that will help to predict and define the functional capacity of spermatozoa. METHODS: We examined whether there is a correlation between semen parameters (count, progressive motility, and morphology) and protein expression/activity of antioxidative defense enzymes in seminal plasma from 10 normospermic subjects. RESULTS: Sperm progressive motility was in positive correlation with seminal plasma protein expression of both superoxide dismutase (SOD) isoforms (MnSOD and CuZnSOD) and catalase. Also, positive correlation was observed between sperm count and MnSOD protein expression, as well as between sperm morphology and protein expression of catalase in seminal plasma. In contrast, protein expression of glutathione peroxidase was not in correlation with any sperm parameter, while its activity negatively correlated with sperm morphology and motility. CONCLUSIONS: These data suggest that evaluation of protein expression of antioxidative defense enzymes in seminal plasma might be of importance in the evaluation of male fertility status and that could be used as an additional biomarker along with classic semen analysis in assessment of semen quality.

Differences in the redox status of human visceral and subcutaneous adipose tissues--relationships to obesity and metabolic risk.

OBJECTIVE: Metabolic homeostasis depends on adipocyte metabolic responses/processes, most of which are redox-regulated. Besides, visceral and subcutaneous adipose tissues (VAT and SAT, respectively) differ metabolically and in their contribution to metabolic complications, but their redox characteristics in humans are still unknown. To understand the molecular mechanisms of metabolic syndrome development, we analysed the redox characteristics of VAT and SAT in groups with various body weights and metabolic risks. MATERIAL AND METHODS: Fifty premenopausal women were classified according to body mass index into normal-weight and obese groups, and these groups were further sub-classified into metabolically healthy and metabolically obese ("at risk") based on the homeostasis model assessment of insulin resistance (HOMA-IR) index and the triglyceride, total-, LDL- and HDL-cholesterol levels. Antioxidant components, NADPH oxidase protein and 4-hydroxynonenal (4-HNE) levels were analysed in VAT and SAT. RESULTS: Compared with the SAT, the VAT showed a higher basal level of glutathione (GSH) and GSH-dependent enzyme activities. Compared with the metabolically healthy normal-weight controls, the obese groups of women showed lower GSH levels in both depots. However, in these groups, additional prooxidative changes (increased NADPH oxidase and 4-HNE and decreased levels of SOD and/or CAT) were observed only in VAT. CONCLUSIONS: Because of the critical role of thiol-redox homeostasis in lipogenesis, interdepot-differences in the GSH-dependent antioxidant part may be connected to the higher metabolic activity found in VAT. Analogously, the lower GSH levels that occur during obesity and the corresponding additional redox imbalance may be signs of VAT metabolic dysfunction that underlie the subsequent metabolic impairment.