Interplay between bioenergetics and oxidative stress at normal brain aging. Aging as a result of increasing disbalance in the system oxidative stress-energy provision

[Recent research on the role of oxidative stress in the pathogenesis of attention deficit hyperactivity disorder]

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents, and its etiology and pathogenesis are still unclear. Brain is the organ with the largest oxygen consumption in human body and is easily affected by oxidative imbalance. Oxidative stress has become the key research direction for the pathogenesis of ADHD, but there is still a lack of relevant studies in China. Based on the latest research findings in China and overseas, this article reviews the clinical and experimental studies on oxidative stress in ADHD and explores the association of oxidative stress with neurotransmitter imbalance, neuroinflammation, and cell apoptosis in the pathogenesis of ADHD, so as to provide new research ideas for exploring the pathogenesis of ADHD.

Exposure to Polystyrene Nanoplastics Led to Learning and Memory Deficits in Zebrafish by Inducing Oxidative Damage and Aggravating Brain Aging

Nanoplastics (NPs) may pass through the blood-brain barrier, giving rise to serious concerns about their potential toxicity to the brain. In this study, the effects of NPs exposure on learning and memory, the primary cognitive functions of the brain, are assessed in zebrafish with classic T-maze exploration tasks. Additionally, to reveal potential affecting mechanisms, the impacts of NPs exposure on brain aging, oxidative damage, energy provision, and the cell cycle are evaluated. The results demonstrate that NP-exposed zebrafish takes significantly longer for their first entry and spends markedly less time in the reward zone in the T-maze task, indicating the occurrence of learning and memory deficits. Moreover, higher levels of aging markers (β-galactosidase and lipofuscin) are detected in the brains of NP-exposed fish. Along with the accumulation of reactive free radicals, NP-exposed zebrafish suffer significant levels of brain oxidative damage. Furthermore, lower levels of Adenosine triphosphate (ATP) and cyclin-dependent kinase 2 and higher levels of p53 are observed in the brains of NP-exposed zebrafish, suggesting that NPs exposure also results in a shortage of energy supply and an arrestment of the cell cycle. These findings suggest that NPs exposure may pose a severe threat to brain health, which deserves closer attention.

Neurotoxicity of melittin: Role of mitochondrial oxidative phosphorylation system in synaptic plasticity dysfunction

Melittin (Mel), a main active peptide component of bee venom, has been proven to possess strong antitumor activity. Previous studies have shown that Mel caused severe cell membrane lysis and acted on the central nervous system (CNS). Here, this study was designed to investigate the effects of Mel on CNS and explore the potential mechanism. We confirmed the neurotoxic effect of melittin by in vivo and in vitro experiments. After subcutaneous administration of Mel (4 mg/kg, 8 mg/kg) for 14 days, the mice exhibited obvious depression-like behavior in a dose dependent manner. Besides, RNA-sequencing analysis revealed that oxidative phosphorylation (OXPHOS) signaling pathway was mostly enriched in hippocampus. Consistently, we found that Mel distinctly inhibited the activity of OXPHOS complex I and induced oxidative stress injury. Moreover, Mel significantly induced synaptic plasticity dysfunction in hippocampus via BDNF/TrkB/CREB signaling pathway. Taken together, the neurotoxic effect of Mel was involved in impairing OXPHOS system and hippocampal synaptic plasticity. These novel findings provide new insights into fully understanding the health risks of Mel and are conducive to the development of Mel related drugs.

Molecular mechanism of caloric restriction mimetics-mediated neuroprotection of age-related neurodegenerative diseases: an emerging therapeutic approach

Aging-induced neurodegenerative diseases (NDs) are significantly increasing health problem worldwide. It has been well documented that oxidative stress is one of the potential causes of aging and age-related NDs. There are no drugs for the treatment of NDs, therefore there is an immediate necessity for the development of strategies/treatments either to prevent or cure age-related NDs. Caloric restriction (CR) and intermittent fasting have been considered as effective strategies in increasing the healthspan and lifespan, but it is difficult to adhere to these routines strictly, which has led to the development of calorie restriction mimetics (CRMs). CRMs are natural compounds that provide similar molecular and biochemical effects of CR, and activate autophagy process. CRMs have been reported to regulate redox signaling by enhancing the antioxidant defense systems through activation of the Nrf2 pathway, and inhibiting ROS generation through attenuation of mitochondrial dysfunction. Moreover, CRMs also regulate redox-sensitive signaling pathways such as the PI3K/Akt and MAPK pathways to promote neuronal cell survival. Here, we discuss the neuroprotective effects of various CRMs at molecular and cellular levels during aging of the brain. The CRMs are envisaged to become a cornerstone of the pharmaceutical arsenal against aging and age-related pathologies.

AFG, an important maillard reaction product in red ginseng, alleviates D-galactose-induced brain aging in mice via correcting mitochondrial dysfunction induced by ROS accumulation

Red ginseng is a classical processed product from Panax ginseng. C.A Meyer with many bioactive components formed through the Maillard reaction called Maillard reaction products. Maillard reaction refers to complex reversible reactions between amino acids or proteins and glycosides, which are used in food processing and storage, as well as in tobacco development, traditional Chinese medicine processing, and wine brewing. Arginyl-fructosyl-glucose (AFG) is a main non-saponin (ginsenoside) component produced in red ginseng processing, with high antioxidant, anti-apoptotic and neuroprotective efficiencies. However, its effects and mechanisms against oxidation stress in on the brain remain elusive. Therefore, this study aimed at exploring the therapeutic effect exerted by AFG on murine subacute brain aging induced by D-galactose (D-gal) and its potential molecular mechanism in the murine model, finding that AFG (40 and 80 mg/kg) significantly ameliorated D-gal-resulted changes in pathology. Besides, according to the transmission electron microscopy (TEM) and Western blot, AFG corrected the mitochondrial dysfunction resulted from ROS, thereby delaying the mice brain aging caused by D-gal.

Aspartame and Its Metabolites Cause Oxidative Stress and Mitochondrial and Lipid Alterations in SH-SY5Y Cells

Due to a worldwide increase in obesity and metabolic disorders such as type 2 diabetes, synthetic sweeteners such as aspartame are frequently used to substitute sugar in the diet. Possible uncertainties regarding aspartame's ability to induce oxidative stress, amongst others, has led to the recommendation of a daily maximum dose of 40 to 50 mg per kg. To date, little is known about the effects of this non-nutritive sweetener on cellular lipid homeostasis, which, besides elevated oxidative stress, plays an important role in the pathogenesis of various diseases, including neurodegenerative diseases such as Alzheimer's disease. In the present study, treatment of the human neuroblastoma cell line SH-SY5Y with aspartame (271.7 µM) or its three metabolites (aspartic acid, phenylalanine, and methanol (271.7 µM)), generated after digestion of aspartame in the human intestinal tract, resulted in significantly elevated oxidative stress associated with mitochondrial damage, which was illustrated with reduced cardiolipin levels, increased gene expression of SOD1/2, PINK1, and FIS1, and an increase in APF fluorescence. In addition, treatment of SH-SY5Y cells with aspartame or aspartame metabolites led to a significant increase in triacylglycerides and phospholipids, especially phosphatidylcholines and phosphatidylethanolamines, accompanied by an accumulation of lipid droplets inside neuronal cells. Due to these lipid-mediating properties, the use of aspartame as a sugar substitute should be reconsidered and the effects of aspartame on the brain metabolism should be addressed in vivo.

Cellular mechanisms in brain aging: Focus on physiological and pathological aging

Aging is a natural phenomenon characterized by accumulation of cellular damage and debris. Oxidative stress, cellular senescence, sustained inflammation, and DNA damage are the main cellular processes characteristic of aging associated with morphological and functional decline. These effects tend to be more pronounced in tissues with high metabolic rates such as the brain, mainly in regions such as the prefrontal cortex, hippocampus, and amygdala. These regions are highly related to cognitive behavior, and therefore their atrophy usually leads to decline in processes such as memory and learning. These cognitive declines can occur in physiological aging and are exacerbated in pathological aging. In this article, we review the cellular processes that underlie the triggers of aging and how they relate to one another, causing the atrophy of nerve tissue that is typical of aging. The main topic of this review to determine the central factor that triggers all the cellular processes that lead to cellular aging and discriminate between normal and pathological aging. Finally, we review how the use of supplements with antioxidant and anti-inflammatory properties reduces the cognitive decline typical of aging, which reinforces the hypothesis of oxidative stress and cellular damage as contributors of physiological atrophy of aging. Moreover, cumulative evidence suggests their possible use as therapies, which improve the aging population's quality of life.

Oxidative stress, inflammation and hormesis: The role of dietary and lifestyle modifications on aging

Oxidative stress (OS) is primarily caused by the formation of free radicals and reactive oxygen species; it is considered as one of the prominent factors in slowing down and degrading cellular machinery of an individual, and it eventually leads to aging and age-related diseases by its continuous higher state. The relation between molecular damage and OS should be particularized to understand the beginning of destruction at the cellular levels, extending outwards to affect tissues, organs, and ultimately to the organism. Several OS biomarkers, which are established at the biomolecular level, are useful in investigating the disease susceptibility during aging. Slowing down the aging process is a matter of reducing the rate of oxidative damage to the cellular machinery over time. The breakdown of homeostasis, the mild overcompensation, the reestablishment of homeostasis, and the adaptive nature of the process are the essential features of hormesis, which incorporates several factors, including calorie restriction, nutrition and lifestyle modifications that play an important role in reducing the OS. In the current review, along with the concept and theories of aging (with emphasis on free radical theory), various manifestations of OS with special attention on mitochondrial dysfunction and age-related diseases have been discussed. To alleviate the OS, hormetic approaches including caloric restriction, exercise, and nutrition have also been discussed.

Influence of Guanine-Based Purines on the Oxidoreductive Reactions Involved in Normal or Altered Brain Functions

The production of reactive oxygen species (ROS) in the brain is homeostatically controlled and contributes to normal neural functions. Inefficiency of control mechanisms in brain aging or pathological conditions leads to ROS overproduction with oxidative neural cell damage and degeneration. Among the compounds showing therapeutic potential against neuro-dysfunctions induced by oxidative stress are the guanine-based purines (GBPs), of which the most characterized are the nucleoside guanosine (GUO) and the nucleobase guanine (GUA), which act differently. Indeed, the administration of GUO to in vitro or in vivo models of acute brain injury (ischemia/hypoxia or trauma) or chronic neurological/neurodegenerative disorders, exerts neuroprotective and anti-inflammatory effects, decreasing the production of reactive radicals and improving mitochondrial function via multiple molecular signals. However, GUO administration to rodents also causes an amnesic effect. In contrast, the metabolite, GUA, could be effective in memory-related disorders by transiently increasing ROS production and stimulating the nitric oxide/soluble guanylate cyclase/cGMP/protein kinase G cascade, which has long been recognized as beneficial for cognitive function. Thus, it is worth pursuing further studies to ascertain the therapeutic role of GUO and GUA and to evaluate the pathological brain conditions in which these compounds could be more usefully used.

Homeostasis of carbohydrates and reactive oxygen species is critically changed in the brain of middle-aged mice: molecular mechanisms and functional reasons

The brain is an organ that consumes a lot of energy. In the brain, energy is required for synaptic transmission, numerous biosynthetic processes and axonal transport in neurons, and for many supportive functions of glial cells. The main source of energy in the brain is glucose and to a lesser extent lactate and ketone bodies. ATP is formed at glucose catabolism via glycolysis and oxidative phosphorylation in mitochondrial electron transport chain (ETC) within mitochondria being the main source of ATP. With age, brain's energy metabolism is disturbed, involving a decrease in glycolysis and mitochondrial dysfunction. The latter is accompanied by intensified generation of reactive oxygen species (ROS) in ETC leading to oxidative stress. Recently, we have found that crucial changes in energy metabolism and intensity of oxidative stress in the mouse brain occur in middle age with minor progression in old age. In this review, we analyze the metabolic changes and functional causes that lead to these changes in the aging brain.

Developing and pilot testing a frailty-focused education and communication training workshop

Objective

To describe development and pilot testing of a multi-modal frailty-focused education and communication training workshop for health care clinicians.

Methods

Pilot testing was conducted via two workshops (#1:face-to-face [2019], #2:virtual [2020]). Participants: convenience sample of clinicians and students who volunteered. Workshop #1 included registered nurses working in an acute care and one medical student (N=14); #2: nursing students enrolled in an APRN program. Design: Pre/post observational study. Data analysis: descriptive statistics, paired t-tests and Wilcoxon rank test.

Results

Statistically significant increases in frailty knowledge (#1: p = 0.02, d = 0.44; #2: p = 0.006, d = 0.55) and self-reported competency with older adult interactions (#1: p < 0.001, d = 0.62; #2: p = 0.001, d = 0.63) were reported for both workshops. Post course evaluations of the workshop were positive, with scores ranging from 3.5-3.9 (range: 0-4) for increased understanding of the concept of frailty, communication to support health-related behavior, and best practice empathic communication skills.

Conclusion

The FCOM workshop was successful. Participants gained knowledge and skills for use in working with older adults across the aging continuum from non-frail to frail.

Innovation

Our FCOM training workshop expands prior communication training on shared decision-making with frail individuals to a broader population of all older adults.

Mesenchymal stem cells and exosomes improve cognitive function in the aging brain by promoting neurogenesis

Biologically speaking, normal aging is a spontaneous and inevitable process of organisms over time. It is a complex natural phenomenon that manifests itself in the form of degenerative changes in structures and the decline of functions, with diminished adaptability and resistance. Brain aging is one of the most critical biological processes that affect the physiological balance between health and disease. Age-related brain dysfunction is a severe health problem that contributes to the current aging society, and so far, there is no good way to slow down aging. Mesenchymal stem cells (MSCs) have inflammation-inhibiting and proliferation-promoting functions. At the same time, their secreted exosomes inherit the regulatory and therapeutic procedures of MSCs with small diameters, allowing high-dose injections and improved therapeutic efficiency. This manuscript describes how MSCs and their derived exosomes promote brain neurogenesis and thereby delay aging by improving brain inflammation.

Assessment of Novel Oligopeptides from Rapeseed Napin (Brassica napus) in Protecting HepG2 Cells from Insulin Resistance and Oxidative Stress

Oligopeptides (Thr-His-Leu-Pro-Lys (THLPK), His-Pro-Leu-Lys (HPLK), Leu-Pro-Lys (LPK), His-Leu-Lys (HLK), and Leu-His-Lys (LHK)) are newly identified from rapeseed napin (Brassica napus) protein-derived hydrolysates with the capability of upregulating glucose transporter-4 (GLUT4) expression and translocation. However, whether each of them enhances GLUT4 expression and translocation and their specific mechanisms remain unclear. Here, we assess the effects of the oligopeptides against insulin resistance (IR) and oxidative stress in hepatocytes and screen out the most antidiabetic one. Specifically, compared with other oligopeptides, LPK not only remarkably elevated glucose consumption to 8.45 mmol/L protein; superoxide dismutase (SOD) activity to 319 U/mg protein; GLUT4 expression and translocation; and phosphorylated level of insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt) (P < 0.05) but also remarkably attenuated the reactive oxygen species (ROS) level to 2255, lactate dehydrogenase (LDH) activity to 20.5 U/mg protein, malondialdehyde (MDA) content to 241 nmol/mg protein, and NO content to 1302 μmol/mL protein (P < 0.05). These findings demonstrated that antidiabetic oligopeptide LPK possessed the most potential to protect HepG2 cells from IR and oxidative stress via activating IRS-1/PI3K/Akt/GLUT4 and regulating common oxidative markers in vitro.

High fat high fructose diet induces mild oxidative stress and reorganizes intermediary metabolism in male mouse liver: Alpha-ketoglutarate effects

BACKGROUND

Diets rich in fats and/or carbohydrates are used to study obesity and related metabolic complications. We studied the effects of a high fat high fructose diet (HFFD) on intermediary metabolism and the development of oxidative stress in mouse liver and tested the ability of alpha-ketoglutarate to prevent HFFD-induced changes.

METHODS

Male mice were fed a standard diet (10% kcal fat) or HFFD (45% kcal fat, 15% kcal fructose) with or without addition of 1% alpha-ketoglutarate (AKG) in drinking water for 8 weeks.

RESULTS

The HFFD had no effect on body mass but activated fructolysis and glycolysis and induced inflammation and oxidative stress with a concomitant increase in activity of antioxidant enzymes in the mouse liver. HFFD-fed mice also showed lower mRNA levels of pyruvate dehydrogenase kinase 4 (PDK4) and slightly increased intensity of mitochondrial respiration in liver compared to mice on the standard diet. No significant effects of HFFD on transcription of PDK2 and PGC1α, a peroxisome proliferator-activated receptor co-activator-1α, or protein levels of p-AMPK, an active form of AMP-activated protein kinase, were found. The addition of AKG to HFFD decreased oxidized glutathione levels, did not affect levels of lipid peroxides and PDK4 transcripts but increased activities of hexokinase and phosphofructokinase in mouse liver.

CONCLUSIONS

Supplementation with AKG had weak modulating effects on HFFD-induced oxidative stress and changes in energetics in mouse liver.

GENERAL SIGNIFICANCE

Our research expands the understanding of diet-induced metabolic switching and elucidates further roles of alpha-ketoglutarate as a metabolic regulator.

Exposure of adult sea urchin Strongylocentrotus intermedius to stranded heavy fuel oil causes developmental toxicity on larval offspring

Heavy fuel oil (HFO) spills pose serious threat to coastlines and sensitive resources. Stranded HFO that occurs along the coastline could cause long-term and massive damage to the marine environment and indirectly affect the survival of parental marine invertebrates. However, our understanding of the complex associations within invertebrates is primarily limited, particularly in terms of the toxicity effects on the offspring when parents are exposed to stranded HFO. Here, we investigated the persistent effects on the early development stage of the offspring following stranded HFO exposure on the sea urchin Strongylocentrotus intermedius. After 21 d exposure, sea urchins exhibited a significant decrease in the reproductive capacity; while the reactive oxygen species level, 3-nitrotyrosine protein level, protein carbonyl level, and heat shock proteins 70 expression in the gonadal tissues and gametes significantly increased as compared to the controls, indicating that HFO exposure could cause development toxicity on offspring in most traits of larval size. These results suggested that the stranded HFO exposure could increase oxidative stress of gonadal tissues, impair reproductive functions in parental sea urchins, and subsequently impact on development of their offspring. This study provides valuable information regarding the persistent toxicity effects on the offspring following stranded HFO exposure on sea urchins.

Interplay between reactive oxygen and nitrogen species in living organisms

In living organisms most oxygen consumed is reduced to water via four-electron reduction. However, few percentages of oxygen are reduced by consecutive one electron mechanisms giving rise to superoxide anion radical, (O₂^•-), hydrogen peroxide (H₂O₂) and hydroxyl radical (HO^•) and their derivatives collectively called reactive oxygen species (ROS). Nitric oxide (^•NO) is produced at oxidation of arginine by nitric oxide synthase (NOS) or at reduction of nitrites by diverse reductases. Interaction of ^•NO with O₂^•- results in formation of peroxinitrite (ONOO^-), a powerful oxidant. Additionally, H₂O₂ can interact with ^•NO resulting in HO^• production. Nitric oxide and its derivatives are collectively called reactive nitrogen species (RNS) and together with ROS they form a group of so-called reactive oxygen/nitrogen species (RONS). Nonspecific effects of RONS are related to their interaction with various components of living organisms, whereas specific effects are based mainly on interaction with specific proteins containing [Fe-S]-clusters and thiol groups of cysteine residues. Most early ROS studies were mainly focused on their deleterious effects, whereas now more delicate mechanisms of their involvement in signaling and toxic processes are under inspection. Studies of RNS activities in biological systems started from their vasodilating effects which lead to discovery of activation of soluble guanylate cyclase. Interestingly, at low ROS and RNS concentrations signaling effects prevail, whereas at their high concentrations they affect biological systems inhibiting due to massive oxidation of cellular components.

Oxidative Stress and Energy Metabolism in the Brain: Midlife as a Turning Point

Neural tissue is one of the main oxygen consumers in the mammalian body, and a plentitude of metabolic as well as signaling processes within the brain is accompanied by the generation of reactive oxygen (ROS) and nitrogen (RNS) species. Besides the important signaling roles, both ROS and RNS can damage/modify the self-derived cellular components thus promoting neuroinflammation and oxidative stress. While previously, the latter processes were thought to progress linearly with age, newer data point to midlife as a critical turning point. Here, we describe (i) the main pathways leading to ROS/RNS generation within the brain, (ii) the main defense systems for their neutralization and (iii) summarize the recent literature about considerable changes in the energy/ROS homeostasis as well as activation state of the brain's immune system at midlife. Finally, we discuss the role of calorie restriction as a readily available and cost-efficient antiaging and antioxidant lifestyle intervention.

Genetic repression of the antioxidant enzymes reduces the lifespan in Drosophila melanogaster

Aging is a biological process associated with gradual loss of function caused by cellular and molecular damages ultimately leading to mortality. Free radicals are implicated in oxidative damage which affects the longevity of organisms. Natural cellular defenses involving antioxidant enzymes delay or prevent oxidative damage and, therefore, influence the aging process and longevity has been shown in many species including Drosophila. We and others have shown that oxidative resistance is an important mechanism in the aging process in Drosophila. Therefore, we hypothesized that repressing endogenous antioxidant defenses shortens longevity in Drosophila. To study the influence of natural defense mechanisms against oxidative stress in aging, we have investigated the effect of genetic repression of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), on longevity in Drosophila using transgenic RNAi flies and in vivo inhibition of the enzymes with chemical inhibitors. RNAi lines of Drosophila viz., UAS-sod1-IR and UAS-cat-IR, are driven ubiquitously using Act5C-Gal4 and Tubulin-Gal4 to achieve the suppression of SOD1 and CAT activities, respectively. We show that genetic repression of SOD1 and CAT by RNAi in transgenic flies led to drastically reduced longevity (SOD1, 77%; CAT, 83%), presenting the evidence for the role of endogenous antioxidant defenses in lifespan extension in Drosophila. Further, our study shows that the enzyme inhibitors, diethyldithiocarbamate and 3-amino-1,2,4-triazole, although lower the enzyme activities in vivo in flies, but did not affect longevity, which could be attributed to the factors such as bioavailability and metabolism of the inhibitors and adaptive mechanisms involving de novo synthesis of the enzymes. Our study of genetic repression using transgenic RNAi provides experimental evidence that extended longevity is associated with endogenous antioxidant defenses and aging is correlated with oxidative stress resistance.

Chamomile as a potential remedy for obesity and metabolic syndrome

Obesity is an increasing health concern related to many metabolic disorders, including metabolic syndrome, diabetes type 2 and cardiovascular diseases. Many studies suggest that herbal products can be useful dietary supplements for weight management due to the presence of numerous biologically active compounds, including antioxidant polyphenols that can counteract obesity-related oxidative stress. In this review we focus on Matricaria chamomilla, commonly known as chamomile, and one of the most popular medicinal plants in the world. Thanks to a high content of phenolic compounds and essential oils, preparations from chamomile flowers demonstrate a number of pharmacological effects, including antioxidant, anti-inflammatory, antimicrobial and sedative actions as well as improving gastrointestinal function. Several recent studies have shown certain positive effects of chamomile preparations in the prevention of obesity and complications of diabetes. These effects were associated with modulation of signaling pathways involving the AMP-activated protein kinase, NF-κB, Nrf2 and PPARγ transcription factors. However, the potential of chamomile in the management of obesity seems to be underestimated. This review summarizes current data on the use of chamomile and its individual components (apigenin, luteolin, essential oils) to treat obesity and related metabolic disorders in cell and animal models and in human studies. Special attention is paid to molecular mechanisms that can be involved in the anti-obesity effects of chamomile preparations. Limitation of chamomile usage is also analyzed.

Oxidative stress concept updated: Definitions, classifications, and regulatory pathways implicated

Reactive oxygen species were discovered in living organisms in the early 1950's and their action has been implicated in diverse biological processes. First formulated by H. Sies in 1985[57], the oxidative stress concept stimulated substantial interest in reactive oxygen species and it is now common that fundamental research in various biomedical fields includes mention of research on the involvement of oxidative stress. Such strong interest has resulted in the development of definitions and classifications of oxidative stress and much research progress in the field. Although we clearly understand the limitations of various definitions or classifications, such parameters may help to provide quantitative descriptions, compare related processes among different laboratories, and introduce some measurable parameters. This paper highlights recent advances in the areas of oxidative stress definitions and the classification of oxidative stresses. Such items are directly associated with our understanding of the molecular mechanisms involved in organismal responses to oxidative insults. The knowledge accumulated to date indicates that selective expression of specific genes is a central player in the adaptive response to oxidative stress and reversible oxidation of cysteine residues of sensor proteins is a key process regulating responses to oxidative stress.