Do glutathione levels decline in aging human brain?

Brain extended and closed forms glutathione levels decrease with age and extended glutathione is associated with visuospatial memory

During aging, the brain is subject to greater oxidative stress (OS), which is thought to play a critical role in cognitive impairment. Glutathione (GSH), as a major antioxidant in the brain, can be used to combat OS. However, how brain GSH levels vary with age and their associations with cognitive function is unclear. In this study, we combined point-resolved spectroscopy and edited spectroscopy sequences to investigate extended and closed forms GSH levels in the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and occipital cortex (OC) of 276 healthy participants (extended form, 166 females, age range 20-70 years) and 15 healthy participants (closed form, 7 females, age range 26-56 years), and examined their relationships with age and cognitive function. The results revealed decreased extended form GSH levels with age in the PCC among 276 participants. Notably, the timecourse of extended form GSH level changes in the PCC and ACC differed between males and females. Additionally, positive correlations were observed between extended form GSH levels in the PCC and OC and visuospatial memory. Additionally, a decreased trend of closed form GSH levels with age was also observed in the PCC among 15 participants. Taken together, these findings enhance our understanding of the brain both closed and extended form GSH time course during normal aging and associations with sex and memory, which is an essential first step for understanding the neurochemical underpinnings of healthy aging.

Brain glutathione and GABA+ levels in autistic children

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by social communication challenges and repetitive behaviors. Altered neurometabolite levels, including glutathione (GSH) and gamma-aminobutyric acid (GABA), have been proposed as potential contributors to the biology underlying ASD. This study investigated whether cerebral GSH or GABA levels differ between a cohort of children aged 8-12 years with ASD (n = 52) and typically developing children (TDC, n = 49). A comprehensive analysis of GSH and GABA levels in multiple brain regions, including the primary motor cortex (SM1), thalamus (Thal), medial prefrontal cortex (mPFC), and supplementary motor area (SMA), was conducted using single-voxel HERMES MR spectroscopy at 3T. The results revealed no significant differences in cerebral GSH or GABA levels between the ASD and TDC groups across all examined regions. These findings suggest that the concentrations of GSH (an important antioxidant and neuromodulator) and GABA (a major inhibitory neurotransmitter) do not exhibit marked alterations in children with ASD compared to TDC. A statistically significant positive correlation was observed between GABA levels in the SM1 and Thal regions with ADHD inattention scores. No significant correlation was found between metabolite levels and hyper/impulsive scores of ADHD, measures of core ASD symptoms (ADOS-2, SRS-P) or adaptive behavior (ABAS-2). While both GSH and GABA have been implicated in various neurological disorders, the current study provides valuable insights into the specific context of ASD and highlights the need for further research to explore other neurochemical alterations that may contribute to the pathophysiology of this complex disorder.

Brain Glutathione and GABA+ levels in autistic children

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by social communication challenges and repetitive behaviors. Altered neurometabolite levels, including glutathione (GSH) and gamma-aminobutyric acid (GABA), have been proposed as potential contributors to the biology underlying ASD. This study investigated whether cerebral GSH or GABA levels differ between a large cohort of children aged 8-12 years with ASD (n=52) and typically developing children (TDC, n=49). A comprehensive analysis of GSH and GABA levels in multiple brain regions, including the primary motor cortex (SM1), thalamus (Thal), medial prefrontal cortex (mPFC), and supplementary motor area (SMA), was conducted using single-voxel HERMES MR spectroscopy at 3T. The results revealed no significant differences in cerebral GSH or GABA levels between the ASD and TDC groups across all examined regions. These findings suggest that the concentrations of GSH (an important antioxidant and neuromodulator) and GABA (a major inhibitory neurotransmitter) do not exhibit marked alterations in children with ASD compared to TDC. A statistically significant positive correlation was observed between GABA levels in the SM1 and Thal regions with ADHD inattention scores. No significant correlation was found between metabolite levels and hyper/impulsive scores of ADHD, measures of core ASD symptoms (ADOS-2, SRS-P) or adaptive behavior (ABAS-2). While both GSH and GABA have been implicated in various neurological disorders, the current study provides valuable insights into the specific context of ASD and highlights the need for further research to explore other neurochemical alterations that may contribute to the pathophysiology of this complex disorder.

Reduced brain glutathione levels during normal aging are associated with visuospatial memory

During aging, the brain is subject to greater oxidative stress (OS), which is thought to play a critical role in cognitive impairment. Glutathione (GSH), as a major antioxidant in the brain, can be used to combatting OS. However, how brain GSH levels vary with age and their associations with cognitive function remain unclear. In this study, we combined point-resolved spectroscopy and edited spectroscopy sequences to investigate GSH levels in the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and occipital cortex (OC) of 276 healthy participants (166 females, age range 20-70 years) and examined their relationships with age and cognitive function. The results revealed decreased GSH levels with age in the PCC among all participants. Notably, the timecourse of GSH level changes in the PCC and ACC differed between males and females. Additionally, positive correlations were observed between GSH levels in the PCC and OC and visuospatial memory. Taken together, these findings enhance our understanding of the brain GSH timecourse during normal aging and associations with sex and memory, which is an essential first step for understanding the neurochemical underpinnings of OS-related diseases.

Quantitation of Brain and Blood Glutathione and Iron in Healthy Age Groups Using Biophysical and In Vivo MR Spectroscopy: Potential Clinical Application

The antioxidant glutathione (GSH) and pro-oxidant iron levels play a balancing role in the modulation of oxidative stress (OS). There is a significant depletion of GSH in the left hippocampus (LH) in patients with Alzheimer's disease (AD) with concomitant elevation of iron level. However, the correlation of GSH and iron distribution patterns between the brain and the peripheral system (blood) is not yet known. We measured GSH and magnetic susceptibility (e.g., iron) in the LH region along with GSH in plasma and iron in serum across four age groups consisting of healthy volunteers (age range 18-72 y, n = 70). We report non-variability of the mean GSH in the plasma and LH region across mentioned age groups. The mean iron level in the LH region does not change, but the iron level in the serum in the 51-72 y age group increases non-significantly. Regression analysis of our data indicated that GSH and iron levels (both in blood and in brain) are not related to age. This research pave the way for the identification of a risk/susceptibility biomarker for AD and Parkinson's disease from the evaluation of GSH (in plasma) and iron (in serum) levels concomitantly.

Milk intake enhances cerebral antioxidant (glutathione) concentration in older adults: A randomized controlled intervention study

Background

A major antioxidant, glutathione (GSH), is a key factor in the antioxidant defense mechanism against oxidative stress and aging-related functional declines. Our previous observational study showed positive correlations between brain GSH concentrations and dairy food consumption, particularly milk (p < 0.001), in older adults.

Objective

To investigate whether a recommended amount of milk intake (3 cups/day) in low dairy consumers enhances brain GSH concentrations through an intervention trial.

Methods

Seventy-three older adults (60–89 years) with a low dairy intake (≤1.5 servings/day) were randomized (5:2 ratio) in this 3-month randomized clinical trial. The intervention group was provided 1% milk weekly and instructed to consume 3 cups of milk/day for 3 months while the control group continued their habitual intake of total dairy ≤ 1.5 servings/day (<1 cup of milk/day). Brain GSH concentrations were measured in the fronto-parietal region using our unique 3 T magnetic resonance chemical shift imaging technique at baseline and 3 months.

Results

Among 73 randomized participants, 66 participants (49 intervention; 17 controls) completed the study. Milk intake in the intervention group increased from 0.2 ± 0.3 cups/day to 3.0 ± 0.6 cups/day (p < 0.001) between baseline and the end of the study, while milk intake in the control group did not differ throughout the study duration (0.4 ± 0.4 cups/day). The intervention group showed increases in brain GSH concentrations by 7.4 ± 11.7% (p < 0.001) in parietal and 4.7 ± 9.8% (p = 0.003) in fronto-parietal regions, and 4.6 ± 8.7% (p < 0.001) in overall brain concentration after the intervention compared with baseline, while the control group showed no changes.

Conclusion

This study provides evidence that milk serves as a good dietary source to increase and/or restore brain GSH concentrations in older adults. Identifying dietary sources that effectively enhance antioxidant defenses and neuroprotection could lead to the development of new strategies to promote brain health in the aging population.

Clinical trial registration

[https://ClinicalTrials.gov], identifier [NCT02957422].

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.

Edited magnetic resonance spectroscopy in the neonatal brain

J-difference-edited spectroscopy is a valuable approach for the detection of low-concentration metabolites with magnetic resonance spectroscopy (MRS). Currently, few edited MRS studies are performed in neonates due to suboptimal signal-to-noise ratio, relatively long acquisition times, and vulnerability to motion artifacts. Nonetheless, the technique presents an exciting opportunity in pediatric imaging research to study rapid maturational changes of neurotransmitter systems and other metabolic systems in early postnatal life. Studying these metabolic processes is vital to understanding the widespread and rapid structural and functional changes that occur in the first years of life. The overarching goal of this review is to provide an introduction to edited MRS for neonates, including the current state-of-the-art in editing methods and editable metabolites, as well as to review the current literature applying edited MRS to the neonatal brain. Existing challenges and future opportunities, including the lack of age-specific reference data, are also discussed.

Common Pathogenetic Mechanisms Underlying Aging and Tumor and Means of Interventions

Recently, there has been an increase in the incidence of malignant tumors among the older population. Moreover, there is an association between aging and cancer. During the process of senescence, the human body suffers from a series of imbalances, which have been shown to further accelerate aging, trigger tumorigenesis, and facilitate cancer progression. Therefore, exploring the junctions of aging and cancer and searching for novel methods to restore the junctions is of great importance to intervene against aging-related cancers. In this review, we have identified the underlying pathogenetic mechanisms of aging-related cancers by comparing alterations in the human body caused by aging and the factors that trigger cancers. We found that the common mechanisms of aging and cancer include cellular senescence, alterations in proteostasis, microbiota disorders (decreased probiotics and increased pernicious bacteria), persistent chronic inflammation, extensive immunosenescence, inordinate energy metabolism, altered material metabolism, endocrine disorders, altered genetic expression, and epigenetic modification. Furthermore, we have proposed that aging and cancer have common means of intervention, including novel uses of common medicine (metformin, resveratrol, and rapamycin), dietary restriction, and artificial microbiota intervention or selectively replenishing scarce metabolites. In addition, we have summarized the research progress of each intervention and revealed their bidirectional effects on cancer progression to compare their reliability and feasibility. Therefore, the study findings provide vital information for advanced research studies on age-related cancers. However, there is a need for further optimization of the described methods and more suitable methods for complicated clinical practices. In conclusion, targeting aging may have potential therapeutic effects on aging-related cancers.

Is There a Glutathione Centered Redox Dysregulation Subtype of Schizophrenia?

Schizophrenia continues to be an illness with poor outcome. Most mechanistic changes occur many years before the first episode of schizophrenia; these are not reversible after the illness onset. A developmental mechanism that is still modifiable in adult life may center on intracortical glutathione (GSH). A large body of pre-clinical data has suggested the possibility of notable GSH-deficit in a subgroup of patients with schizophrenia. Nevertheless, studies of intracortical GSH are not conclusive in this regard. In this review, we highlight the recent ultra-high field magnetic resonance spectroscopic studies linking GSH to critical outcome measures across various stages of schizophrenia. We discuss the methodological steps required to conclusively establish or refute the persistence of GSH-deficit subtype and clarify the role of the central antioxidant system in disrupting the brain structure and connectivity in the early stages of schizophrenia. We propose in-vivo GSH quantification for patient selection in forthcoming antioxidant trials in psychosis. This review offers directions for a promising non-dopaminergic early intervention approach in schizophrenia.

In Vivo Brain GSH: MRS Methods and Clinical Applications

Glutathione (GSH) is an important antioxidant implicated in several physiological functions, including the oxidation−reduction reaction balance and brain antioxidant defense against endogenous and exogenous toxic agents. Altered brain GSH levels may reflect inflammatory processes associated with several neurologic disorders. An accurate and reliable estimation of cerebral GSH concentrations could give a clear and thorough understanding of its metabolism within the brain, thus providing a valuable benchmark for clinical applications. In this context, we aimed to provide an overview of the different magnetic resonance spectroscopy (MRS) technologies introduced for in vivo human brain GSH quantification both in healthy control (HC) volunteers and in subjects affected by different neurological disorders (e.g., brain tumors, and psychiatric and degenerative disorders). Additionally, we aimed to provide an exhaustive list of normal GSH concentrations within different brain areas. The definition of standard reference values for different brain areas could lead to a better interpretation of the altered GSH levels recorded in subjects with neurological disorders, with insights into the possible role of GSH as a biomarker and therapeutic target.

In Vivo Brain Glutathione is Higher in Older Age and Correlates with Mobility

Brain markers of oxidative damage increase with advancing age. In response, brain antioxidant levels may also increase with age, although this has not been well investigated. Here, we used edited magnetic resonance spectroscopy to quantify endogenous levels of glutathione (GSH, one of the most abundant brain antioxidants) in 37 young [mean: 21.8 (2.5) years; 19 female] and 23 older adults [mean: 72.8 (8.9) years; 19 female]. Accounting for age-related atrophy, we identified higher frontal and sensorimotor GSH levels for the older compared with the younger adults. For the older adults only, higher sensorimotor (but not frontal) GSH was correlated with poorer balance and gait. This suggests a regionally specific relationship between higher brain oxidative stress levels and motor performance declines with age. We suggest these findings reflect an upregulation of GSH in response to increasing brain oxidative stress with normal aging. Together, these results provide insight into age differences in brain antioxidant levels and implications for motor function.

Metabolomic Characterization of Pediatric Acute-Onset Neuropsychiatric Syndrome (PANS)

Introduction

PANS is a controversial clinical entity, consisting of a complex constellation of psychiatric symptoms, adventitious changes, and expression of various serological alterations, likely sustained by an autoimmune/inflammatory disease. Detection of novel biomarkers of PANS is highly desirable for both diagnostic and therapeutic management of affected patients. Analysis of metabolites has proven useful in detecting biomarkers for other neuroimmune-psychiatric diseases. Here, we utilize the metabolomics approach to determine whether it is possible to define a specific metabolic pattern in patients affected by PANS compared to healthy subjects.

Design

This observational case-control study tested consecutive patients referred for PANS between June 2019 to May 2020. A PANS diagnosis was confirmed according to the PANS working criteria (National Institute of Mental Health [NIMH], 2010). Healthy age and sex-matched subjects were recruited as controls.

Methods

Thirty-four outpatients referred for PANS (mean age 9.5 years; SD 2.9, 71% male) and 25 neurotypical subjects matched for age and gender, were subjected to metabolite analysis. Serum samples were obtained from each participant and were analyzed using Nuclear Magnetic Resonance (NMR) spectroscopy. Subsequently, multivariate and univariate statistical analyses and Receiver Operator Curves (ROC) were performed.

Results

Separation of the samples, in line with the presence of PANS diagnosis, was observed by applying a supervised model (R²X = 0.44, R²Y = 0.54, Q² = 0.44, p-value < 0.0001). The significantly altered variables were 2-Hydroxybutyrate, glycine, glutamine, histidine, tryptophan. Pathway analysis indicated that phenylalanine, tyrosine, and tryptophan metabolism, as well as glutamine and glutamate metabolism, exhibited the largest deviations from neurotypical controls.

Conclusion

We found a unique plasma metabolic profile in PANS patients, significantly differing from that of healthy children, that suggests the involvement of specific patterns of neurotransmission (tryptophan, glycine, histamine/histidine) as well as a more general state of neuroinflammation and oxidative stress (glutamine, 2-Hydroxybutyrate, and tryptophan-kynurenine pathway) in the disorder. This metabolomics study offers new insights into biological mechanisms underpinning the disorder and supports research of other potential biomarkers implicated in PANS.

Responsive Expression of MafF to β-Amyloid-Induced Oxidative Stress

The small musculoaponeurotic fibrosarcoma (sMaf) proteins MafF, MafG, and MafK are basic region leucine zipper- (bZIP-) type transcription factors and display tissue- or stimulus-specific expression patterns. As the oxidative stress reactive proteins, sMafs are implicated in various neurological disorders. In the present study, the expressions of sMafs were investigated across five databases gathering transcriptomic data from 74 Alzheimer's disease (AD) patients and 66 controls in the Gene Expression Omnibus (GEO) database. The expression of MafF was increased in the hippocampus of AD patients, which was negatively correlated with the expression of the glutamate cysteine ligase catalytic subunit (GCLC). Furthermore, MafF was significantly increased in patients with Braak stage V-VI, compared to those with Braak stage III-IV. β-Amyloid (Aβ), a strong inducer of oxidative stress, plays a crucial role in the pathogenesis of AD. The responsive expressions of sMafs to Aβ-induced oxidative stress were studied in the APP/PS1 mouse model of AD, Aβ intrahippocampal injection rats, and several human cell lines from different tissue origins. This study revealed that only the induction of MafF was accompanied with reduction of GCLC and glutathione (GSH). MafF knockdown suppressed the increase of GSH induced by Aβ. Among sMafs, MafF is the most responsive to Aβ-induced oxidative stress and might potentiate the inhibition of antioxidation. These results provide a better understanding of sMaf modulation in AD and highlight MafF as a potential therapeutic target in AD.

Molecular Mechanisms and Genetics of Oxidative Stress in Alzheimer's Disease

Alzheimer’s disease is the most common neurodegenerative disorder that can cause dementia in elderly over 60 years of age. One of the disease hallmarks is oxidative stress which interconnects with other processes such as amyloid-β deposition, tau hyperphosphorylation, and tangle formation. This review discusses current thoughts on molecular mechanisms that may relate oxidative stress to Alzheimer’s disease and identifies genetic factors observed from in vitro, in vivo, and clinical studies that may be associated with Alzheimer’s disease-related oxidative stress.

Age-induced accumulation of methylmalonic acid promotes tumour progression

From age 65 onwards, the risk of cancer incidence and associated mortality is substantially higher^1–6. Nonetheless, our understanding of the complex relationship between age and cancer is still in its infancy^2,3,7,8. For decades, this link has largely been attributed to increased exposure time to mutagens in older individuals. However, this view does not account for the well-established role of diet, exercise and small molecules that target the pace of metabolic aging^9–12. Here, we show that metabolic alterations that occur with age can render a systemic environment favorable to progression and aggressiveness of tumors. Specifically, we show that methylmalonic acid (MMA), a by-product of propionate metabolism, is significantly up-regulated in the serum of older people, and functions as a mediator of tumor progression. We traced this to MMA’s ability to induce SOX4 and consequently eliciting a transcriptional reprogramming that can endow cancer cells with aggressive properties. Thus, accumulation of MMA represents a novel link between aging and cancer progression, implicating MMA as a novel therapeutic target for advanced carcinomas.

Concentration, distribution, and influence of aging on the 18 kDa translocator protein in human brain: Implications for brain imaging studies

Positron emission tomography (PET) imaging of the translocator protein (TSPO) is widely used as a biomarker of microglial activation. However, TSPO protein concentration in human brain has not been optimally quantified nor has its regional distribution been compared to TSPO binding. We determined TSPO protein concentration, change with age, and regional distribution by quantitative immunoblotting in autopsied human brain. Brain TSPO protein concentration (>0.1 ng/µg protein) was higher than those reported by in vitro binding assays by at least 2 to 70 fold. TSPO protein distributed widely in both gray and white matter regions, with distribution in major gray matter areas ranked generally similar to that of PET binding in second-generation radiotracer studies. TSPO protein concentration in frontal cortex was high at birth, declined precipitously during the first three months, and increased modestly during adulthood/senescence (10%/decade; vs. 30% for comparison astrocytic marker GFAP). As expected, TSPO protein levels were significantly increased (+114%) in degenerating putamen in multiple system atrophy, providing further circumstantial support for TSPO as a gliosis marker. Overall, findings show some similarities between TSPO protein and PET binding characteristics in the human brain but also suggest that part of the TSPO protein pool might be less available for radioligand binding.

Acrolein is involved in ischemic stroke-induced neurotoxicity through spermidine/spermine-N1-acetyltransferase activation

BACKGROUND AND PURPOSE

Ischemic stroke is the most common type of cerebrovascular event and is responsible for approximately 85% of all strokes in Taiwan. Neurons contain high concentrations of polyamines, which are prone to various pathological states in the brain and are perturbed after cerebral ischemia. Acrolein, an α,β-unsaturated aldehyde, has been suggested as the primary culprit of neuronal damage in stroke patients. However, the mechanism by which acrolein induces neuronal damage during ischemic stroke is not clear.

METHODS

Urinary 3-hydroxypropyl mercapturic acid (3-HPMA), an acrolein-glutathione (GSH) metabolite, plasma acrolein-protein conjugates (Acr-PC) and plasma GSH levels were analyzed to correlate disease severity and prognosis of stroke patients compared with control subjects. In vivo middle cerebral artery occlusion (MCAO) animal models and an in vitro oxygen glucose deprivation (OGD) stroke model were used to investigate the mechanisms of acrolein-induced neuronal damage.

RESULTS

A deregulated acrolein metabolism, including significantly increased plasma Acr-PC levels, decreased urinary 3-HPMA levels and decreased plasma GSH levels, was found in stroke patients compared to control subjects. We further observed that acrolein was produced during ischemia resulting in brain damage in in vivo MCAO animal model. The induction of acrolein in neuronal cells during OGD occurred due to the increased expression of spermidine/spermine N1-acetyltransferase (SSAT) by NF-kB pathway activation. In addition, acrolein elicited a vicious cycling of oxidative stress resulting in neurotoxicity. Finally, N-acetylcysteine effectively prevented OGD-induced neurotoxicity by scavenging acrolein.

CONCLUSION

Overall, our current results demonstrate that acrolein is a culprit of neuronal damage through GSH depletion in stroke patients. The mechanism underlying the role of acrolein in stroke-related neuronal damage occurs through SSAT-induced polyamine oxidation by NF-kB pathway activation. These results provide a novel mechanism of neurotoxicity in stroke patients, aid in the development of neutralizing or preventive measures, and further our understanding of neural protection.

Brain region-specific effects of long-term caloric restriction on redox balance of the aging rat

Caloric restriction (CR) is the most effective intervention to improve health span and extend lifespan in preclinical models. This anti-aging effect of CR is related to attenuation of oxidative damage in various tissues, with divergent results in the brain. We addressed how brain oxidoreductive balance would be modulated in male Sprague-Dawley (SD) rats submitted to a 40% CR from 8 to 19 months of age, by reference to ad libitum-fed (AL) rats at 2 and 19 months of age. Four brain structures were compared: hippocampus, striatum, parietal cortex, cerebellum. Our CR diet elicits significant prevention of oxidative damages with the upregulation of antioxidant defenses (levels of glutathione [GSH], mRNAs of clusterin and of three key antioxidant enzymes) as compared to age-matched AL controls, in a strikingly region-specific pattern. CR also prevented a drastic rise of the glial fibrillary acidic protein in the hippocampus of old AL rats. Besides, the CR effects at age 19 months mainly consist in improving endogenous defenses before the onset of age-related redox alterations. These effects are more prominent in the hippocampus.

Normal glutathione levels in autopsied brain of chronic users of heroin and of cocaine

BACKGROUND

Animal studies suggest that exposure to either of the two widely used drugs of abuse, heroin or cocaine, causes depletion of the antioxidant, reduced glutathione, a hallmark of oxidative stress, in the brain. However, the relevance of the animal findings to the human is uncertain and clinical trials with the antioxidant GSH precursor n-acetylcysteine have produced mixed results in cocaine dependence.

METHODS

Our major objective was to compare glutathione levels, determined by an HPLC-coulometric procedure, in autopsied brain of chronic heroin (n = 11) and cocaine users (n = 9), who were positive for the drugs in the brain, to those of matched controls (n = 16). Six brain regions were examined, including caudate, hippocampus, thalamus and frontal, temporal and insular cortices.

RESULTS

In contrast to experimental animal findings, we found no statistically significant difference between mean levels of reduced or oxidized glutathione in the drug user vs. control groups. Moreover, no correlation was found between levels of drugs in the brain and those of glutathione.

CONCLUSIONS

Acknowledging the many generic limitations of an autopsied human brain study and the preliminary nature of the findings, our data nevertheless suggest that any oxidative stress caused by heroin or cocaine in chronic users of the drugs might not be sufficient to cause substantial loss of stores of glutathione in the human brain, at least during early withdrawal. These findings, requiring replication, might also have some relevance to future clinical trials employing glutathione supplement therapy as an anti-oxidative strategy in chronic users of the two abused drugs.

Interaction between TSPO-a neuroimmune marker-and redox status in clinical high risk for psychosis: a PET-MRS study

Altered neuroimmune response and oxidative stress have both been implicated in the pathophysiology of schizophrenia. While preclinical studies have proposed several pathways regarding potential interactions between oxidative stress and neuroimmune imbalance in the development of psychosis, the molecular mechanisms underlying this interaction are not yet understood. To date, no study has investigated this link in vivo in the human brain. We conducted the first in vivo study linking translocator protein 18  kDa (TSPO) expression and glutathione (a major brain antioxidant and a marker for redox status) in the medial prefrontal cortex (mPFC) of a relatively large sample of participants (N = 48) including 27 antipsychotic-naïve individuals at clinical high risk for psychosis and 21 matched healthy volunteers using high-resolution PET with TSPO radioligand, [18F]FEPPA, and 3T proton magnetic resonance spectroscopy (1H MRS). The omnibus model (including TSPO genotype as covariate) was significant (F(4, 43) = 10.01, p < 0.001), with a significant group interaction (t = -2.10, p = 0.04), suggesting a different relation between [18F]FEPPA VT and glutathione in each clinical group. In healthy volunteers, but not in individuals at clinical high risk for psychosis, we found a significant negative association between glutathione levels and [18F]FEPPA VT (r = -0.60, p = 0.006). We observed no significant group differences with respect to [18F]FEPPA VT or glutathione levels. These findings suggest an abnormal interaction between TSPO expression and redox status in the clinical high risk states for psychosis.

Healthy brain aging: Interplay between reactive species, inflammation and energy supply

Brains' high energy expenditure with preferable utilization of glucose and ketone bodies, defines the specific features of its energy homeostasis. The extensive oxidative metabolism is accompanied by a concomitant generation of high amounts of reactive oxygen, nitrogen, and carbonyl species, which will be here collectively referred to as RONCS. Such metabolism in combination with high content of polyunsaturated fatty acids creates specific problems in maintaining brains' redox homeostasis. While the levels of products of interaction between RONCS and cellular components increase slowly during the first two trimesters of individuals' life, their increase is substantially accelerated towards the end of life. Here we review the main mechanisms controlling the redox homeostasis of the mammalian brain, their age-dependencies as well as their adaptive potential, which might turn out to be much higher than initially assumed. According to recent data, the organism seems to respond to the enhancement of aging-related toxicity by forming a new homeostatic set point. Therefore, further research will focus on understanding the properties of the new set point(s), the general nature of this phenomenon and will explore the limits of brains' adaptivity.

Aging exacerbates cognitive and anxiety alterations induced by an intracerebroventricular injection of amyloid-β1-42 peptide in mice

An increasing body of evidence indicates that the activation of indoleamine-2,3-dyoxigenase (IDO), a first and rate-limiting enzyme in the kynurenine (KYN) pathway, is involved in Aβ_1-42-neurotoxicity and AD pathogenesis. We have reported for the first time that brain IDO activation is related to Aβ_1-42 exposure in young mice. Because aging is characterized by a brain dyshomeostasis and because it remains the most dominant risk factor for AD, the purpose of this study was to determine whether aging is associated with a higher sensitivity to behavioural and neurochemical alterations elicited by an intracerebroventricular (i.c.v.) injection of Aβ_1-42 (400 pmol/mice), and whether KYN pathway is involved in these effects. We confirmed that aged mice displayed higher cognitive deficit in the object recognition test and higher anxiety-like behaviour in the elevated plus-maze and open field tests after the Aβ_1-42 administration. Aged mice also responded to Aβ_1-42 with a higher deficiency of brain-derived neurotrophic factor, glutathione levels and total radical-trapping antioxidant capacity, a higher IDO activity, and a higher KYN and KYN/tryptophan ratio in the prefrontal cortex and hippocampus. These effects of Aβ_1-42 were associated with a higher proinflammatory status, as measured by higher levels of interleukin-6, lower levels of interleukin-10 and higher expression of glial fibrillary acidic protein (GFAP) and allograft inflammatory factor 1 (Iba1) in the brain of aged mice. These results represent primary evidence suggesting that age-associated inflammatory signature and down-regulation of neuroprotectants in the brain render aged mice more vulnerable to Aβ_1-42-induced memory loss, anxiety symptoms and KYN pathway dysregulation.

Measuring Cerebral and Cerebellar Glutathione in Children Using 1H MEGA-PRESS MRS

BACKGROUND AND PURPOSE

Glutathione is an important antioxidant in the human brain and therefore of interest in neurodegenerative disorders. The purpose of this study was to investigate the feasibility of measuring glutathione in healthy nonsedated children by using the ¹H Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence at 3T and to compare glutathione levels between the medial parietal gray matter and the cerebellum.

MATERIALS AND METHODS

Glutathione was measured using MEGA-PRESS MRS (TR = 1.8 seconds, TE = 131 ms) in the parietal gray matter (35 × 25 × 20 mm³) of 6 healthy children (10.0 ± 2.4 years of age; range, 7-14 years; 3 males) and in the cerebellum of 11 healthy children (12.0 ± 2.7 years of age; range, 7-16 years; 6 males). A postprocessing pipeline was developed to account for frequency and phase variations in the edited ON and nonedited OFF spectra. Metabolites were quantified with LCModel and reported both as ratios and water-scaled values. Glutathione was quantified in the ON-OFF spectra, whereas total NAA, total Cho, total Cr, mIns, Glx, and taurine were quantified in the OFF spectra.

RESULTS

We found significantly higher glutathione, total Cho, total Cr, mIns, and taurine in the cerebellum (P < .01). Glx and total NAA were significantly higher in the parietal gray matter (P < .01). There was no significant difference in glutathione/total Cr (P = .93) between parietal gray matter and cerebellum.

CONCLUSIONS

We demonstrated that glutathione measurement in nonsedated children is feasible. We found significantly higher glutathione in the cerebellum compared with the parietal gray matter. Metabolite differences between the parietal gray matter and cerebellum agree with published MRS data in adults.

Redox Signaling Mediated by Thioredoxin and Glutathione Systems in the Central Nervous System

SIGNIFICANCE

The thioredoxin (Trx) and glutathione (GSH) systems play important roles in maintaining the redox balance in the brain, a tissue that is prone to oxidative stress due to its high-energy demand. These two disulfide reductase systems are active in various areas of the brain and are considered to be critical antioxidant systems in the central nervous system (CNS). Various neuronal disorders have been characterized to have imbalanced redox homeostasis. Recent Advances: In addition to their detrimental effects, recent studies have highlighted that reactive oxygen species/reactive nitrogen species (ROS/RNS) act as critical signaling molecules by modifying thiols in proteins. The Trx and GSH systems, which reversibly regulate thiol modifications, regulate redox signaling involved in various biological events in the CNS.

CRITICAL ISSUES

In this review, we focus on the following: (i) how ROS/RNS are produced and mediate signaling in CNS; (ii) how Trx and GSH systems regulate redox signaling by catalyzing reversible thiol modifications; (iii) how dysfunction of the Trx and GSH systems causes alterations of cellular redox signaling in human neuronal diseases; and (iv) the effects of certain small molecules that target thiol-based signaling pathways in the CNS.

FUTURE DIRECTIONS

Further study on the roles of thiol-dependent redox systems in the CNS will improve our understanding of the pathogenesis of many human neuronal disorders and also help to develop novel protective and therapeutic strategies against neuronal diseases. Antioxid. Redox Signal. 27, 989-1010.

Glutathione, the Major Redox Regulator, in the Prefrontal Cortex of Individuals at Clinical High Risk for Psychosis

INTRODUCTION

Oxidative stress and glutathione dysregulation have been implicated in the etiology of schizophrenia. To date, most in vivo studies have investigated alterations in cerebral glutathione levels in patients in which the disorder is already established; however, whether oxidative stress actually predates the onset of psychosis remains unknown. In the current study, we investigated cerebral glutathione levels of antipsychotic-naïve individuals at clinical high risk for psychosis. As exploratory analyses, we also investigated the associations between cerebral glutathione levels and peripheral glutathione peroxidase activity and clinical and neuropsychological measures.

METHODS

Glutathione levels were measured in the medial prefrontal cortex of 30 clinical high risk (n=26 antipsychotic naïve) and 26 healthy volunteers using 3T proton magnetic resonance spectroscopy. Each participant was assessed for glutathione peroxidase activity in plasma and genotyped for the glutamate cysteine ligase catalytic subunit polymorphism.

RESULTS

No significant differences were observed in glutathione levels between clinical high risk and healthy volunteers in the medial prefrontal cortex (F(1,54)=0.001, P =0.98). There were no significant correlations between cerebral glutathione levels and clinical and neuropsychological measures. Similarly, no significant differences were found in peripheral glutathione peroxidase activity between clinical high risk and healthy volunteers (F(1,37)=0.15, P =0.70). However, in clinical high risk, we observed a significant effect of lifetime history of cannabis use on glutathione peroxidase activity (F(1,23)=7.41, P =0.01).

DISCUSSION

The lack of significant differences between antipsychotic naïve clinical high risk and healthy volunteers suggests that alterations in glutathione levels in medial prefrontal cortex are not present in the clinical high risk state.

Conditional Human Immunodeficiency Virus Transactivator of Transcription Protein Expression Induces Depression-like Effects and Oxidative Stress

BACKGROUND

The prevalence of major depression in those with HIV/AIDS is substantially higher than in the general population. Mechanisms underlying this comorbidity are poorly understood. HIV-transactivator of transcription (Tat) protein, produced and excreted by HIV, could be involved. We determined whether conditional Tat protein expression in mice is sufficient to induce depression-like behaviors and oxidative stress. Further, as oxidative stress is associated with depression, we determined whether decreasing or increasing oxidative stress by administering methylsulfonylmethane (MSM) or diethylmaleate (DEM), respectively, altered depression-like behavior.

METHODS

GT-tg bigenic mice received intraperitoneal saline or doxycycline (Dox, 25-100 mg/kg/day) to induce Tat expression. G-tg mice, which do not express Tat protein, also received Dox. Depression-like behavior was assessed with the tail suspension test (TST) and the two-bottle saccharin/water consumption task. Reactive oxygen/nitrogen species (ROS/RNS) were assessed ex vivo. Medial frontal cortex (MFC) oxidative stress and temperature were measured in vivo with 9.4-Tesla proton magnetic resonance spectroscopy (MRS).

RESULTS

Tat expression increased TST immobility time in an exposure-dependent manner and reduced saccharin consumption. MSM decreased immobility time while DEM increased it in saline-treated GT-tg mice. Tat and MSM behavioral effects persisted for 28 days. Tat and DEM increased while MSM decreased ROS/RNS levels. Tat expression increased MFC glutathione levels and temperature.

CONCLUSIONS

Tat expression induced rapid and enduring depression-like behaviors and oxidative stress. Increasing/decreasing oxidative stress increased/decreased, respectively, depression-like behavior. Thus, Tat produced by HIV may contribute to the high depression prevalence among those with HIV. Further, mitigation of oxidative stress could reduce depression severity.