Elevated oxidative stress and sensorimotor deficits but normal cognition in mice that cannot synthesize ascorbic acid

Ascorbate insufficiency disrupts glutamatergic signaling and alters electroencephalogram phenotypes in a mouse model of Alzheimer's disease

Clinical studies have reported that increased epileptiform and subclinical epileptiform activity can be detected in many patients with an Alzheimer's disease (AD) diagnosis using electroencephalogram (EEG) and this may correlate with poorer cognition. Ascorbate may have a specific role as a neuromodulator in AD as it is released concomitantly with glutamate reuptake following excitatory neurotransmission. Insufficiency may therefore result in an exacerbated excitatory/inhibitory imbalance in neuronal signaling. Using a mouse model of AD that requires dietary ascorbate (Gulo-/-APPswe/PSEN1dE9), EEG was recorded at baseline and during 4 weeks of ascorbate depletion in young (5-month-old) and aged (20-month-old) animals. Data were scored for changes in quantity of spike trains, individual spikes, sleep-wake rhythms, sleep fragmentation, and brainwave power bands during light periods each week. We found an early increase in neuronal spike discharges with age and following ascorbate depletion in AD model mice and not controls, which did not correlate with brain amyloid load. Our data also show more sleep fragmentation with age and with ascorbate depletion. Additionally, changes in brain wave activity were observed within different vigilance states in both young and aged mice, where Gulo-/-APPswe/PSEN1dE9 mice had shifts towards higher frequency bands (alpha, beta, and gamma) and ascorbate depletion resulted in shifts towards lower frequency bands (delta and theta). Microarray data supported ascorbate insufficiency altering glutamatergic transmission through the decreased expression of glutamate related genes, however no changes in protein expression of glutamate reuptake transporters were observed. These data suggest that maintaining optimal brain ascorbate levels may support normal brain electrical activity and sleep patterns, particularly in AD patient populations where disruptions are observed.

Circadian organization of clock factors, antioxidant defenses, and cognitive genes expression, is lost in the cerebellum of aged rats. Possible targets of therapeutic strategies for the treatment of age-related cerebellar disorders

Aging is a major risk factor for cognitive deficits, impaired locomotion, and gait disorders. Although oxidative stress and circadian disruption are involved in both normal aging and the pathogenesis of age-associated diseases, just a very few studies explore the consequences of aging on circadian rhythms in the cerebellum. Here, we investigated age-dependent changes in the circadian organization of the molecular clock, antioxidant defenses and synaptic plasticity-related factors, in the rat cerebellum, and discussed the impact of that altered temporal organization on the cognitive function of this brain area. Particularly, we examined the circadian patterns of Brain and muscle ARNT-like 1 (BMAL1) protein levels, Glutathione peroxidase 4 (GPx4) gene expression, GPx and Catalase (CAT) enzymes activity, reduced glutathione (GSH) levels, and the Brain-derived neurotrophic factor (Bdnf) and its Tyrosine kinase receptor B (TrkB) circadian expression. Endogenously-driven circadian rhythms of BMAL1, GPx4, CAT, GSH, and Bdnf/TrkB factors, were observed in the young rat cerebellum. The rhythms' acrophases show a circadian organization that might be crucial for the daily cerebellar-dependent cognitive functions. Notably, aging disrupted circadian rhythms and the temporal organization of BMAL1, antioxidant defenses, and cognitive Bdnf/TrkB gene expression. Increased oxidative stress and disruption of clock-controlled rhythms during aging, might precede and cause the loss of circadian organization in the aged cerebellum. We expect our results highlight circadian rhythms of the studied factors as new targets for the treatment of age-dependent cerebellar disorders.

Modulation of microglia activation by the ascorbic acid transporter SVCT2

Neuroinflammation is a major characteristic of pathology in several neurodegenerative diseases. Microglia, the brain's resident myeloid cells, shift between activation states under neuroinflammatory conditions, both responding to, but also driving damage in the brain. Vitamin C (ascorbate) is an essential antioxidant for central nervous system function that may have a specific role in the neuroinflammatory response. Uptake of ascorbate throughout the central nervous system is facilitated by the sodium-dependent vitamin C transporter 2 (SVCT2). SVCT2 transports the reduced form of ascorbate into neurons and microglia, however the contribution of altered SVCT2 expression to the neuroinflammatory response in microglia is not well understood. In this study we demonstrate that SVCT2 expression modifies microglial response, as shown through changes in cell morphology and mRNA expression, following a mild traumatic brain injury (mTBI) in mice with decreased or increased expression of SVCT2. Results were supported by in vitro studies in an immortalized microglial cell line and in primary microglial cultures derived from SVCT2-heterozygous and transgenic animals. Overall, this work demonstrates the importance of SVCT2 and ascorbate in modulating the microglial response to mTBI and suggests a potential role for both in response to neuroinflammatory challenges.

Electroacupuncture at ST25 corrected gut microbial dysbiosis and SNpc lipid peroxidation in Parkinson's disease rats

Introduction

Parkinson's disease (PD) remains one kind of a complex, progressive neurodegenerative disease. Levodopa and dopamine agonists as widely utilized PD therapeutics have not shown significant positive long-term outcomes. Emerging evidences indicate that electroacupuncture (EA) have potential effects on the therapy of nervous system disorders, particularly PD, but its specific underlying mechanism(s) remains poorly understood, leading to the great challenge of clinical application and management. Previous study has shown that acupuncture ameliorates PD motor symptoms and dopaminergic neuron damage by modulating intestinal dysbiosis, but its intermediate pathway has not been sufficiently investigated.

Methods

A rat model of PD was induced using rotenone. The therapeutic effect of EA on PD was assessed using the pole and rotarod tests and immunohistostaining for tyrosine hydroxylase (TH) in the substantia nigra (SN) of brain. The role of gut microbiota was explored using 16S rRNA gene sequencing and metabonomic analysis. PICRUSt2 analysis, lipidomic analysis, LPS and inflammatory factor assays were used for subsequent exploration and validation. Correlation analysis was used to identify the key bacteria that EA regulates lipid metabolism to improve PD.

Results

The present study firstly reappeared the effects of EA on protecting motor function and dopaminergic neurons and modulation of gut microbial dysbiosis in rotenone-induced PD rat model. EA improved motor dysfunction (via the pole and rotarod tests) and protected TH+ neurons in PD rats. EA increased the abundance of beneficial bacteria such as Lactobacillus, Dubosiella and Bifidobacterium and decreased the abundance of Escherichia-Shigella and Morganella belonging to Pseudomonadota, suggesting that the modulation of gut microbiota by EA improving the symptoms of PD motility via alleviating LPS-induced inflammatory response and oxidative stress, which was also validated by various aspects such as microbial gene functional analysis, fecal metabolomics analysis, LPS and inflammatory factor assays and SNpc lipidomics analysis. Moreover, correlation analyses also verified strong correlations of Escherichia-Shigella and Morganella with motor symptoms and SNpc lipid peroxidation, explicating targets and intermediate pathways through which EA improve PD exercise symptom.

Conclusion

Our results indicate that the improvement of motor function in PD model by EA may be mediated in part by restoring the gut microbiota, which intermediate processes involve circulating endotoxins and inflammatory mediators, SNpc oxidative stress and lipid peroxidation. The gut-microbiome - brain axis may be a potential mechanism of EA treatment for the PD.

Druggable transcriptomic pathways revealed in Parkinson's patient-derived midbrain neurons

Complex genetic predispositions accelerate the chronic degeneration of midbrain substantia nigra neurons in Parkinson’s disease (PD). Deciphering the human molecular makeup of PD pathophysiology can guide the discovery of therapeutics to slow the disease progression. However, insights from human postmortem brain studies only portray the latter stages of PD, and there is a lack of data surrounding molecular events preceding the neuronal loss in patients. We address this gap by identifying the gene dysregulation of live midbrain neurons reprogrammed in vitro from the skin cells of 42 individuals, including sporadic and familial PD patients and matched healthy controls. To minimize bias resulting from neuronal reprogramming and RNA-seq methods, we developed an analysis pipeline integrating PD transcriptomes from different RNA-seq datasets (unsorted and sorted bulk vs. single-cell and Patch-seq) and reprogramming strategies (induced pluripotency vs. direct conversion). This PD cohort’s transcriptome is enriched for human genes associated with known clinical phenotypes of PD, regulation of locomotion, bradykinesia and rigidity. Dysregulated gene expression emerges strongest in pathways underlying synaptic transmission, metabolism, intracellular trafficking, neural morphogenesis and cellular stress/immune responses. We confirmed a synaptic impairment with patch-clamping and identified pesticides and endoplasmic reticulum stressors as the most significant gene-chemical interactions in PD. Subsequently, we associated the PD transcriptomic profile with candidate pharmaceuticals in a large database and a registry of current clinical trials. This study highlights human transcriptomic pathways that can be targeted therapeutically before the irreversible neuronal loss. Furthermore, it demonstrates the preclinical relevance of unbiased large transcriptomic assays of reprogrammed patient neurons.

Ascorbate Is a Primary Antioxidant in Mammals

Ascorbate (vitamin C in primates) functions as a cofactor for a number of enzymatic reactions represented by prolyl hydroxylases and as an antioxidant due to its ability to donate electrons, which is mostly accomplished through non-enzymatic reaction in mammals. Ascorbate directly reacts with radical species and is converted to ascorbyl radical followed by dehydroascorbate. Ambiguities in physiological relevance of ascorbate observed during in vivo situations could be attributed in part to presence of other redox systems and the pro-oxidant properties of ascorbate. Most mammals are able to synthesize ascorbate from glucose, which is also considered to be an obstacle to verify its action. In addition to animals with natural deficiency in the ascorbate synthesis, such as guinea pigs and ODS rats, three strains of mice with genetic removal of the responsive genes (GULO, RGN, or AKR1A) for the ascorbate synthesis have been established and are being used to investigate the physiological roles of ascorbate. Studies using these mice, along with ascorbate transporter (SVCT)-deficient mice, largely support its ability in protection against oxidative insults. While combined actions of ascorbate in regulating epigenetics and antioxidation appear to effectively prevent cancer development, pharmacological doses of ascorbate and dehydroascorbate may exert tumoricidal activity through redox-dependent mechanisms.

Identification of an exporter that regulates vitamin C supply from blood to the brain

Vitamin C (VC) distribution in our body requires VC transporters. However, mammalian VC exporters are yet to be identified. Herein, to unravel this long-standing mystery, we focused on the pathways whereby VC moves from blood to the brain, which should require a VC entrance and exit system composed of an importer and a latent exporter. Via cell-based transport analyses of VC efflux and using knockout mice generated via the CRISPR-Cas9 system, we identified GLUT12/SLC2A12 as a physiologically important VC efflux protein expressed in the choroid plexus; Glut12/Slc2a12 knockout halved the cerebral VC levels, markedly increased VC accumulation in the choroid plexus, and reduced the cerebrospinal fluid VC levels. These findings facilitate our understanding of VC regulation and the physiological impact of VC in our body.

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A long-standing mystery in vitamin C handling in mammalians was uncovered

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GLUT12 was identified as a physiologically important vitamin C efflux protein—VCEP

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GLUT12 is expressed in the choroid plexus and acts as a vitamin C exporter

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Glut12 knockout halved the cerebral vitamin C levels in mice

Vitamin C Deficiency in the Young Brain-Findings from Experimental Animal Models

Severe and long-term vitamin C deficiency can lead to fatal scurvy, which is fortunately considered rare today. However, a moderate state of vitamin C (vitC) deficiency (hypovitaminosis C)-defined as a plasma concentration below 23 μM-is estimated to affect up to 10% of the population in the Western world, albeit clinical hallmarks in addition to scurvy have not been linked to vitC deficiency. The brain maintains a high vitC content and uniquely high levels during deficiency, supporting vitC's importance in the brain. Actions include both antioxidant and co-factor functions, rendering vitamin C deficiency likely to affect several targets in the brain, and it could be particularly significant during development where a high cellular metabolism and an immature antioxidant system might increase sensitivity. However, investigations of a non-scorbutic state of vitC deficiency and effects on the developing young brain are scarce. This narrative review provides a comprehensive overview of the complex mechanisms that regulate vitC homeostasis in vivo and in the brain in particular. Functions of vitC in the brain and the potential consequences of deficiency during brain development are highlighted, based primarily on findings from experimental animal models. Perspectives for future investigations of vitC are outlined.

Ascorbate deficiency decreases dopamine release in gulo-/- and APP/PSEN1 mice

Dopamine (DA) has important roles in learning, memory, and motivational processes and is highly susceptible to oxidation. In addition to dementia, Alzheimer's disease (AD) patients frequently exhibit decreased motivation, anhedonia, and sleep disorders, suggesting deficits in dopaminergic neurotransmission. Vitamin C (ascorbate, ASC) is a critical antioxidant in the brain and is often depleted in AD patients as a result of disease-related oxidative stress and dietary deficiencies. To probe the effects of ASC deficiency and AD pathology on the DAergic system, gulo-/- mice, which like humans depend on dietary ASC to maintain adequate tissue levels, were crossed with APP/PSEN1 mice and provided sufficient or depleted ASC supplementation from weaning until 12 months of age. Ex vivo fast-scan cyclic voltammetry showed that chronic ASC depletion and APP/PSEN1 genotype both independently decreased dopamine release in the nucleus accumbens, a hub for motivational behavior and reward, while DA clearance was similar across all groups. In striatal tissue containing nucleus accumbens, low ASC treatment led to decreased levels of DA and its metabolites 3,4-dihydroxyohenyl-acetic acid (DOPAC), 3-methoxytyramine (3-MT), and homovanillic acid (HVA). Decreased enzyme activity observed through lower pTH/TH ratio was driven by a cumulative effect of ASC depletion and APP/PSEN1 genotype. Together the data show that deficits in dopaminergic neurotransmission resulting from age and disease status are magnified in conditions of low ASC which decrease DA availability during synaptic transmission. Such deficits may contribute to the non-cognitive behavioral changes observed in AD including decreased motivation, anhedonia, and sleep disorders.

Decreased content of ascorbic acid (vitamin C) in the brain of knockout mouse models of Na+,K+-ATPase-related neurologic disorders

Na⁺,K⁺-ATPase is a crucial protein responsible for maintaining the electrochemical gradients across the cell membrane. The Na⁺,K⁺-ATPase is comprised of catalytic α, β, and γ subunits. In adult brains, the α3 subunit, encoded by ATP1A3, is predominantly expressed in neurons, whereas the α2 subunit, encoded by ATP1A2, is expressed in glial cells. In foetal brains, the α2 is expressed in neurons as well. Mutations in α subunits cause a variety of neurologic disorders. Notably, the onset of symptoms in ATP1A2- and ATP1A3-related neurologic disorders is usually triggered by physiological or psychological stressors. To gain insight into the distinct roles of the α2 and α3 subunits in the developing foetal brain, whose developmental dysfunction may be a predisposing factor of neurologic disorders, we compared the phenotypes of mouse foetuses with double homozygous knockout of Atp1a2 and Atp1a3 (α2α3-dKO) to those with single knockout. The brain haemorrhage phenotype of α2α3-dKO was similar to that of homozygous knockout of the gene encoding ascorbic acid (ASC or vitamin C) transporter, SVCT2. The α2α3-dKO brain showed significantly decreased level of ASC compared with the wild-type (WT) and single knockout. We found that the ASC content in the basal ganglia and cerebellum was significantly lower in the adult Atp1a3 heterozygous knockout mouse (α3-HT) than in the WT. Interestingly, we observed a significant decrease in the ASC level in the basal ganglia and cerebellum of α3-HT in the peripartum period, during which mice are under physiological stress. These observations indicate that the α2 and α3 subunits independently contribute to the ASC level in the foetal brain and that the α3 subunit contributes to ASC transport in the adult basal ganglia and cerebellum. We propose that decreases in ASC levels may affect neural network development and are linked to the pathophysiology of ATP1A2- and ATP1A3-related neurologic disorders.

Immunomodulatory role of reactive oxygen species and nitrogen species during T cell-driven neutrophil-enriched acute and chronic cutaneous delayed-type hypersensitivity reactions

Rationale: Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important regulators of inflammation. The exact impact of ROS/RNS on cutaneous delayed-type hypersensitivity reaction (DTHR) is controversial. The aim of our study was to identify the dominant sources of ROS/RNS during acute and chronic trinitrochlorobenzene (TNCB)-induced cutaneous DTHR in mice with differently impaired ROS/RNS production. Methods: TNCB-sensitized wild-type, NADPH oxidase 2 (NOX2)- deficient (gp91^phox-/-), myeloperoxidase-deficient (MPO^-/-), and inducible nitric oxide synthase-deficient (iNOS^-/-) mice were challenged with TNCB on the right ear once to elicit acute DTHR and repetitively up to five times to induce chronic DTHR. We measured ear swelling responses and noninvasively assessed ROS/RNS production in vivo by employing the chemiluminescence optical imaging (OI) probe L-012. Additionally, we conducted extensive ex vivo analyses of inflamed ears focusing on ROS/RNS production and the biochemical and morphological consequences. Results: The in vivo L-012 OI of acute and chronic DTHR revealed completely abrogated ROS/RNS production in the ears of gp91^phox-/- mice, up to 90 % decreased ROS/RNS production in the ears of MPO^-/- mice and unaffected ROS/RNS production in the ears of iNOS^-/- mice. The DHR flow cytometry analysis of leukocytes derived from the ears with acute DTHR confirmed our in vivo L-012 OI results. Nevertheless, we observed no significant differences in the ear swelling responses among all the experimental groups. The histopathological analysis of the ears of gp91^phox-/- mice with acute DTHRs revealed slightly enhanced inflammation. In contrast, we observed a moderately reduced inflammatory immune response in the ears of gp91^phox-/- mice with chronic DTHR, while the inflamed ears of MPO^-/- mice exhibited the strongest inflammation. Analyses of lipid peroxidation, 8-hydroxy-2'deoxyguanosine levels, redox related metabolites and genomic expression of antioxidant proteins revealed similar oxidative stress in all experimental groups. Furthermore, inflamed ears of wild-type and gp91^phox-/- mice displayed neutrophil extracellular trap (NET) formation exclusively in acute but not chronic DTHR. Conclusions: MPO and NOX2 are the dominant sources of ROS/RNS in acute and chronic DTHR. Nevertheless, depletion of one primary source of ROS/RNS exhibited only marginal but conflicting impact on acute and chronic cutaneous DTHR. Thus, ROS/RNS are not a single entity, and each species has different properties at certain stages of the disease, resulting in different outcomes.

The Effect of Perioperative Vitamin C on Postoperative Analgesic Consumption: A Meta-Analysis of Randomized Controlled Trials

Because the analgesic effect of vitamin C against acute pain remains poorly addressed, this meta-analysis aimed at investigating its effectiveness against acute postoperative pain. A total of seven randomized controlled trials with placebo/normal controls were identified from PubMed, Cochrane Library, Medline, Google Scholar, and Embase databases. Pooled analysis showed a lower pain score (standardized mean difference (SMD) = -0.68, 95% CI: -1.01 to -0.36, p < 0.0001; I2 = 57%) and a lower morphine consumption (weighted mean difference (WMD) = -2.44 mg, 95% CI: -4.03 to -0.86, p = 0.003; I2 = 52%) in the vitamin group than that in the placebo group within postoperative 1-2 h. At postoperative 24 h, a lower pain score (SMD = -0.65, 95% CI: -1.11 to -0.19, p = 0.005; I2 = 81%) and lower morphine consumption (WMD = -6.74 mg, 95% CI: -9.63 to -3.84, p < 0.00001; I2 = 85%) were also noted in the vitamin group. Subgroup analyses demonstrated significant reductions in pain severity and morphine requirement immediately (1-2 h) and 24 h after surgery for patients receiving intravenous vitamin C but not in the oral subgroup. These findings showed significant reductions in pain score and opioid requirement up to postoperative 24 h, respectively, suggesting the effectiveness of perioperative vitamin C use. Further large-scale trials are warranted to elucidate its optimal intravenous dosage and effectiveness against chronic pain in the postoperative pain control setting.

Traditional Korean herbal formulae, Yuk-Mi-Ji-Hwang-Tang, ameliorates impairment of hippocampal memory ability by chronic restraint stress of mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Yuk-Mi-Jihwang-Tang (YJT) has been popularly prescribed to treat aging related disorders over than hundreds of years in East Asia countries.

AIM OF THE STUDY

To investigate possible modulatory actions of YJT on chronic restraint stress (CRS)-induced neurodegeneration on hippocampus neuronal injuries.

MATERIALS AND METHODS

Mice were orally administered with YJT (100, 200, or 400 mg/kg) or ascorbic acid (100 mg/kg) before 4 h of stress for 28 days. Morris water maze task was completed from day 24th to 28th, and stress hormones and biochemical analyzes were measured.

RESULTS

Four weeks of the CRS abnormally affected memory impairments by measurement of escape latency and time spent in the target quadrant. Additionally, neurotransmitters were also drastically altered in serum or hippocampus protein levels by CRS. Gene expressions for 5-hydroxytryptamine (5-HT) receptor, 5-HT-transport, and tryptophan hydroxylase were also altered, whereas YJT led to normalize the above alterations. Additionally, YJT also beneficially worked on endogenous redox system as well as inflammatory reactions in the hippocampal neurons. We observed that hippocampal excitotoxicity was induced by CRS which were evidenced by depletion of phosphor-cAMP response element-binding protein, brain-derived neurotrophic factor, nuclear factor erythroid-2-related factor 2, heme oxygenase-1 and abnormally increases of acetylcholine esterase activities in hippocampus protein levels; however, YJT considerably improved the above pathological conditions.

CONCLUSIONS

Our findings supported YJT enhance memory function via regulation of hippocampal excitotoxicity-derived memory impairment, stress hormone, and endogenous redox, respectively.

A Cecal Slurry Mouse Model of Sepsis Leads to Acute Consumption of Vitamin C in the Brain

Vitamin C (ascorbate, ASC) is a critical antioxidant in the body with specific roles in the brain. Despite a recent interest in vitamin C therapies for critical care medicine, little is known about vitamin C regulation during acute inflammation and critical illnesses such as sepsis. Using a cecal slurry (CS) model of sepsis in mice, we determined ASC and inflammatory changes in the brain following the initial treatment. ASC levels in the brain were acutely decreased by approximately 10% at 4 and 24 h post CS treatment. Changes were accompanied by a robust increase in liver ASC levels of up to 50%, indicating upregulation of synthesis beginning at 4 h and persisting up to 7 days post CS treatment. Several key cytokines interleukin 6 (IL-6), interleukin 1β (IL-1β), tumor necrosis factor alpha (TNFα), and chemokine (C-X-C motif) ligand 1 (CXCL1, KC/Gro) were also significantly elevated in the cortex at 4 h post CS treatment, although these levels returned to normal by 48 h. These data strongly suggest that ASC reserves are directly challenged throughout illness and recovery from sepsis. Given the timescale of this response, decreases in cortical ASC are likely driven by hyper-acute neuroinflammatory processes. However, future studies are required to confirm this relationship and to investigate how this deficiency may subsequently impact neuroinflammation.

Neurobiology of vitamin C: Expanding the focus from antioxidant to endogenous neuromodulator

Ascorbic acid (AA) is a water-soluble vitamin (C) found in all bodily organs. Most mammals synthesize it, humans are required to eat it, but all mammals need it for healthy functioning. AA reaches its highest concentration in the brain where both neurons and glia rely on tightly regulated uptake from blood via the glucose transport system and sodium-coupled active transport to accumulate and maintain AA at millimolar levels. As a prototype antioxidant, AA is not only neuroprotective, but also functions as a cofactor in redox-coupled reactions essential for the synthesis of neurotransmitters (e.g., dopamine and norepinephrine) and paracrine lipid mediators (e.g., epoxiecoisatrienoic acids) as well as the epigenetic regulation of DNA. Although redox capacity led to the promotion of AA in high doses as potential treatment for various neuropathological and psychiatric conditions, ample evidence has not supported this therapeutic strategy. Here, we focus on some long-neglected aspects of AA neurobiology, including its modulatory role in synaptic transmission as demonstrated by the long-established link between release of endogenous AA in brain extracellular fluid and the clearance of glutamate, an excitatory amino acid. Evidence that this link can be disrupted in animal models of Huntington´s disease is revealing opportunities for new research pathways and therapeutic applications (e.g., epilepsy and pain management). In fact, we suggest that improved understanding of the regulation of endogenous AA and its interaction with key brain neurotransmitter systems, rather than administration of AA in excess, should be the target of future brain-based therapies.

Lentiviral-mediated knock-down of GD3 synthase protects against MPTP-induced motor deficits and neurodegeneration

Converging evidence demonstrates an important role for gangliosides in brain function and neurodegenerative diseases. Exogenous GM1 is broadly neuroprotective, including in rodent, feline, and primate models of Parkinson's disease, and has shown positive effects in clinical trials. We and others have shown that inhibition of the ganglioside biosynthetic enzyme GD3 synthase (GD3S) increases endogenous levels GM1 ganglioside. We recently reported that targeted deletion of St8sia1, the gene that codes for GD3S, prevents motor impairments and significantly attenuates neurodegeneration induced by 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The current study investigated the effects of GD3S inhibition on the neurotoxicity and parkinsonism induced by MPTP. Mice were injected intrastriatally with a lentiviral-vector-mediated shRNA construct targeting GD3S (shGD3S) or a scrambled-sequence control (scrRNA). An MPTP regimen of 18 mg/kg x 5 days reduced tyrosine-hydroxylase-positive neurons in the substantia nigra pars compacta of scrRNA-treated mice by nearly two-thirds. In mice treated with shGD3S the MPTP-induced lesion was approximately half that size. MPTP induced bradykinesia and deficits in fine motor skills in mice treated with scrRNA. These deficits were absent in shGD3S-treated mice. These results suggest that inhibition of GD3S protects against the nigrostriatal damage, bradykinesia, and fine-motor-skill deficits associated with MPTP administration.

Antioxidants prevent inflammation and preserve the optic projection and visual function in experimental neurotrauma

We investigated the role of oxidative stress and the inflammasome in trauma-induced axon degeneration and vision loss using a mouse model. The left eyes of male mice were exposed to over-pressure air waves. Wild-type C57Bl/6 mice were fed normal, high-vitamin-E (VitE), ketogenic or ketogenic-control diets. Mice lacking the ability to produce vitamin C (VitC) were maintained on a low-VitC diet. Visual evoked potentials (VEPs) and retinal superoxide levels were measured in vivo. Tissue was collected for biochemical and histological analysis. Injury increased retinal superoxide, decreased SOD2, and increased cleaved caspase-1, IL-1α, IL-1β, and IL-18 levels. Low-VitC exacerbated the changes and the high-VitE diet mitigated them, suggesting that oxidative stress led to the increase in IL-1α and activation of the inflammasome. The injury caused loss of nearly 50% of optic nerve axons at 2 weeks and astrocyte hypertrophy in mice on normal diet, both of which were prevented by the high-VitE diet. The VEP amplitude was decreased after injury in both control-diet and low-VitC mice, but not in the high-VitE-diet mice. The ketogenic diet also prevented the increase in superoxide levels and IL-1α, but had no effect on IL-1β. Despite this, the ketogenic diet preserved optic nerve axons, prevented astrocyte hypertrophy, and preserved the VEP amplitude. These data suggest that oxidative stress induces priming and activation of the inflammasome pathway after neurotrauma of the visual system. Further, blocking the activation of the inflammasome pathway may be an effective post-injury intervention.

Feeding Vitamin C during Neonatal and Juvenile Growth Improves Learning and Memory of Rats

We investigated the effects of feeding vitamin C (Vit C) during neonatal and juvenile growth on learning and memory of rats. Rats after delivery were randomly divided into four groups and treated. Group 1, control group, received normal drinking water. Groups 2-4 received Vit C 10, 100, and 500 mg/kg, respectively, from the first day. After 8 weeks, 10 male offspring of each group were randomly selected and tested in the Morris water maze (MWM) and passive avoidance (PA) tests. Finally, the brains were removed for biochemical measurement. In MWM, 10-500 mg/kg Vit C reduced the latency and traveled distance and increased time spent in the target quadrant. In PA, 10 and 100 mg/kg of Vit C increased the latency; 10-500 mg/kg of Vit C decreased the malondialdehyde (MDA) in the brain tissues and increased thiol and catalase (CAT) activity compared to the control group. We showed that feeding rats Vit C during neonatal and juvenile growth has positive effects on learning and memory.

Altered glutamate clearance in ascorbate deficient mice increases seizure susceptibility and contributes to cognitive impairment in APP/PSEN1 mice

Ascorbate (vitamin C) is critical as a first line of defense antioxidant within the brain, and specifically within the synapse. Ascorbate is released by astrocytes during glutamate clearance and disruption of this exchange mechanism may be critical in mediating glutamate toxicity within the synapse. This is likely even more critical in neurodegenerative disorders with associated excitotoxicity and seizures, in particular Alzheimer's disease, in which ascorbate levels are often low. Using Gulo^-/- mice that are dependent on dietary ascorbate, we established that low brain ascorbate increased sensitivity to kainic acid as measured via behavioral observations, electroencephalography (EEG) measurements, and altered regulation of several glutamatergic system genes. Kainic acid-induced immobility was improved in wild-type mice following treatment with ceftriaxone, which upregulates glutamate transporter GLT-1. The same effect was not observed in ascorbate-deficient mice in which sufficient ascorbate is not available for release. A single, mild seizure event was sufficient to disrupt performance in the water maze in low-ascorbate mice and in APP_SWE/PSEN1_dE9 mice. Together, the data support the critical role of brain ascorbate in maintaining protection during glutamatergic hyperexcitation events, including seizures. The study further supports a role for mild, subclinical seizures in cognitive decline in Alzheimer's disease.

Oxidative Stress Levels in the Brain Are Determined by Post-Mortem Interval and Ante-Mortem Vitamin C State but Not Alzheimer's Disease Status

The current study highlighted several changes in measures of oxidative stress and antioxidant status that take place in the mouse brain over the course of 24 h post-mortem. Ascorbic acid (vitamin C) and glutathione both decreased significantly in cortex in as little as 2 h and malondialdehyde levels increased. Further change from baseline was observed up to 24 h, including carbonyl and sulfhydryl formation. The greatest changes were observed in brains that began with low ascorbic acid levels (gulo^{&minus;/&minus;} mice) compared to wild-type or 5XFAD mice. Cortical samples from nine Alzheimer&rsquo;s Disease cases and five controls were also assayed under the same conditions. Post mortem intervals ranged from 6 to 47 h and all samples had low ascorbic acid levels at time of measurement. Malondialdehyde levels were lower in Alzheimer&rsquo;s Disease cases. Despite a strong positive correlation between ascorbic acid and glutathione levels, no other correlations among oxidative stress measures or post mortem interval were observed. Together the data suggest that molecular changes occurring within the first hours of death may mask differences between patient groups. Care must be taken interpreting studies in human brain tissue where ante-mortem nutrient status is not known to avoid bias or confounding of results.

Early Life Vitamin C Deficiency Does Not Alter Morphology of Hippocampal CA1 Pyramidal Neurons or Markers of Synaptic Plasticity in a Guinea Pig Model

Approximately 15% of the Western world population, including pregnant women and their children, is characterized as vitamin C (vitC) deficient. In guinea pigs, early life vitC deficiency causes spatial memory deficits, decreased hippocampal volume and neuron numbers, in otherwise clinically healthy animals. We hypothesized that vitC deficiency leads to decreased brain-derived neurotrophic factor and synaptic plasticity markers in selected brain areas (frontal cortex, hippocampus and striatum) and cause morphological changes in cornu ammonis 1 pyramidal neurons of the hippocampus either through a direct effect or indirectly by increased oxidative stress. Fifty-seven female guinea pigs were allocated to three groups receiving either 1390, 100 or 0–50 mg vitC/kg feed for 11 weeks. Dietary vitC levels were reflected in the plasma, cortical and adrenal gland levels, however, redox imbalance was only present in the adrenal glands allowing for the investigation of a direct influence of vitC deficiency on the chosen parameters in the brain. Synaptic plasticity markers were not affected in the investigated brain areas and no differences in isolated pyramidal neuron morphology was recorded. Based on our findings, it appears that vitC deficiency may primarily elicit impaired neuronal function through increased levels of oxidative stress.

Ascorbic acid and sodium benzoate synergistically aggravates testicular dysfunction in adult Wistar rats

BACKGROUND

The effect of the concomitant use of sodium benzoate (NaB) and ascorbic acid on human health remains controversial. Therefore, the current study is designed to investigate the effect of NaB and ascorbic acid on the testicular function of adult Wistar rats.

METHODS

Adult Wistar rats were randomly allotted into Control (vehicle; received 1 ml of distilled water), NaB-treated (SB-treated; received 100 mg/kg body weight; b.w), ascorbic acid-treated (AA-treated; received 150 mg/kg b.w) and NaB+ ascorbic acid-treated (SB+AA-treated) groups. The treatment lasted for 28 days and the administration was given orally. The body weight change was monitored. Semen analysis, biochemical assay and histological examination were performed.

RESULTS

Treatment with NaB significantly altered the cytoarchitecture of testicular tissue, sperm quality, testicular endocrine function and oxidative stress status without any alteration in body weight gain compared to control. In addition, treatment with NaB+ ascorbic acid exacerbated testicular tissue disruption, impaired sperm quality and testicular endocrine impairment with significant reduction in oxidative stress and unaltered body weight gain when compared with NaB-treated group.

CONCLUSION

This study suggests that ascorbic acid and NaB synergistically aggravates testicular dysfunction. This is independent of oxidative stress status.

Yuk-Mi-Jihwang-Tang, a Traditional Korean Multiple Herbal Formulae, Improves Hippocampal Memory on Scopolamine Injection-Induced Amnesia Model of C57BL/6 Mice

We evaluated neuropharmacological properties of Yuk-Mi-Jihwang-Tang (YJT) against scopolamine injection-induced memory impairment mice model. Mice were orally administered with YJT (50, 100, or 200 mg/kg) or tacrine (TAC, 12.5 mg/kg) for 10 days. At the first day of Morris water maze task, scopolamine (2 mg/kg) was intraperitoneally injected before 30 min of it. The hippocampal memory function was determined by the Morris water maze task for 5 days consecutively. Scopolamine drastically increased escape latency and decreased time spent in target quadrant. Pretreatment YJT properly improved them. Regarding the redox status, YJT significantly reduced the oxidative stress and it also exerted much effort to improve both superoxide dismutase and catalase activities in hippocampal gene expression and protein levels. These effects were well coincided with immunohistochemical analysis of 4-hydroxyneal-positive signals in hippocampal areas. Additionally, acetylcholine esterase activities and brain-derived neurotrophic factor abnormalities in the hippocampal protein levels were significantly normalized by YJT, and their related molecules were also improved. The neuronal proliferation in hippocampal regions was markedly inhibited by scopolamine, whereas YJT notably recovered them. Collectively, YJT exerts much effort to enhance memorial functions through improving redox status homeostasis and partially regulates acetylcholine esterase activities as well as neuronal cell proliferation.

Mitochondrial dysfunction in the APP/PSEN1 mouse model of Alzheimer's disease and a novel protective role for ascorbate

Mitochondrial dysfunction is elevated in very early stages of Alzheimer's disease and exacerbates oxidative stress, which contributes to disease pathology. Mitochondria were isolated from 4-month-old wild-type mice, transgenic mice carrying the APP_SWE and PSEN1_dE9 mutations, mice with decreased brain and mitochondrial ascorbate (vitamin C) via heterozygous knockout of the sodium dependent vitamin C transporter (SVCT2^+/-) and transgenic APP/PSEN1 mice with heterozygous SVCT2 expression. Mitochondrial isolates from SVCT2^+/- mice were observed to consume less oxygen using high-resolution respirometry, and also exhibited decreased mitochondrial membrane potential compared to wild type isolates. Conversely, isolates from young (4 months) APP/PSEN1 mice consumed more oxygen, and exhibited an increase in mitochondrial membrane potential, but had a significantly lower ATP/ADP ratio compared to wild type isolates. Greater levels of reactive oxygen species were also produced in mitochondria isolated from both APP/PSEN1 and SVCT2^+/- mice compared to wild type isolates. Acute administration of ascorbate to mitochondria isolated from wild-type mice increased oxygen consumption compared with untreated mitochondria suggesting ascorbate may support energy production. This study suggests that both presence of amyloid and ascorbate deficiency can contribute to mitochondrial dysfunction, even at an early, prodromal stage of Alzheimer's disease, although occurring via different pathways. Ascorbate may, therefore, provide a useful preventative strategy against neurodegenerative disease, particularly in populations most at risk for Alzheimer's disease in which stores are often depleted through mitochondrial dysfunction and elevated oxidative stress.

Targeted deletion of GD3 synthase protects against MPTP-induced neurodegeneration

Parkinson's disease is a debilitating neurodegenerative condition for which there is no cure. Converging evidence implicates gangliosides in the pathogenesis of several neurodegenerative diseases, suggesting a potential new class of therapeutic targets. We have shown that interventions that simultaneously increase the neuroprotective GM1 ganglioside and decrease the pro-apoptotic GD3 ganglioside - such as inhibition of GD3 synthase (GD3S) or administration of sialidase - are neuroprotective in vitro and in a number of preclinical models. In this study, we investigated the effects of GD3S deletion on parkinsonism induced by 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP was administered to GD3S-/- mice or controls using a subchronic regimen consisting of three series of low-dose injections (11 mg/kg/day × 5 days each, 3 weeks apart), and motor function was assessed after each. The typical battery of tests used to assess parkinsonism failed to detect deficits in MPTP-treated mice. More sensitive measures - such as the force-plate actimeter and treadmill gait parameters - detected subtle effects of MPTP, some of which were absent in mice lacking GD3S. In wild-type mice, MPTP destroyed 53% of the tyrosine-hydroxylase (TH)-positive neurons in the substantia nigra pars compacta (SNc) and reduced striatal dopamine 60.7%. In contrast, lesion size was only 22.5% in GD3S-/- mice and striatal dopamine was reduced by 37.2%. Stereological counts of Nissl-positive SNc neurons that did not express TH suggest that neuroprotection was complete but TH expression was suppressed in some cells. These results show that inhibition of GD3S has neuroprotective properties in the MPTP model and may warrant further investigation as a therapeutic target.

Oxidative stress, serotonergic changes and decreased ultrasonic vocalizations in a mouse model of Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome is an inherited monogenic disorder in which mutations to the 7-dehydrocholesterol (7-DHC) reductase (Dhcr7) gene lead to deficits in cholesterol synthesis. As a result, many patients suffer from gross physiological and neurological deficits. The purpose of this study was to identify a potential abnormal behavioral phenotype in a compound mutant mouse model for Smith-Lemli-Opitz disease (Dhcr7 ^Δ3-5/T93M ) to further validate the model and to provide potential targets for future therapeutic interventions. We also sought to identify some of the underlying changes in brain function that may be responsible for behavioral differences among groups. The Dhcr7 compound mutant mice were smaller than their single mutant littermates. Both single and compound heterozygous mice made fewer ultrasonic vocalizations when separated from the dam, which may suggest a communication deficit in these animals. Striking increases of the highly oxidizable 7-DHC were observed in the compound mutant mice. 7-Dehydrocholesterol is the precursor to cholesterol and builds up because of decreased function of the mutated Dhcr7 enzyme. Additionally, several differences were noted in the serotonergic system including increased expression of the serotonin transporter and increased uptake of serotonin by isolated synaptosomes. We propose that changes to the oxidative environment during development can have a significant impact on the development of serotonergic function and that this contributes to behavioral differences observed in the mutant mice.

Vitamin C modulates the metabolic and cytokine profiles, alleviates hepatic endoplasmic reticulum stress, and increases the life span of Gulo-/- mice

Suboptimal intake of dietary vitamin C (ascorbate) increases the risk of several chronic diseases but the exact metabolic pathways affected are still unknown. In this study, we examined the metabolic profile of mice lacking the enzyme gulonolactone oxidase (Gulo) required for the biosynthesis of ascorbate. Gulo^−/− mice were supplemented with 0%, 0.01%, and 0.4% ascorbate (w/v) in drinking water and serum was collected for metabolite measurements by targeted mass spectrometry. We also quantified 42 serum cytokines and examined the levels of different stress markers in liver. The metabolic profiles of Gulo^−/− mice treated with ascorbate were different from untreated Gulo^−/− and normal wild type mice. The cytokine profiles of Gulo^−/− mice, in return, overlapped the profile of wild type animals upon 0.01% or 0.4% vitamin C supplementation. The life span of Gulo^−/− mice increased with the amount of ascorbate in drinking water. It also correlated significantly with the ratios of serum arginine/lysine, tyrosine/phenylalanine, and the ratio of specific species of saturated/unsaturated phosphatidylcholines. Finally, levels of hepatic phosphorylated endoplasmic reticulum associated stress markers IRE1α and eIF2α correlated inversely with serum ascorbate and life span suggesting that vitamin C modulates endoplasmic reticulum stress response and longevity in Gulo^−/− mice.

Multiple free-radical scavenging (MULTIS) capacity in cattle serum

Multiple free-radical scavenging (MULTIS) activity in cattle and human sera was evaluated with electron spin resonance spectroscopy. Scavenging rates against six active species, namely hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen were quantified. The difference in the electron spin resonance signal intensity in the presence and absence of the serum was converted into the scavenging rates. Comparative MULTIS measurements were made in sera from eight beef cattle, three fetal calves and fifteen healthy human volunteers. Further, we determined the MULTIS value of albumin, the most abundant component in serum. MULTIS values in cattle sera indicated higher scavenging activity against most free radical species tested than human sera. In particular, cattle serum scavenging activities against superoxide and methyl radical were higher than human serum by 2.6 and 3.7 fold, respectively. In cattle serum, albumin appears to play a dominant role in MULTIS activity, but in human serum that is not the case. Previous data indicated that the abundance of uric acid in bovine blood is nearly 80% less than humans; however, this difference does not explain the deviation in MULTIS profile.

Effect of Intravenous High Dose Vitamin C on Postoperative Pain and Morphine Use after Laparoscopic Colectomy: A Randomized Controlled Trial

Background and Objective. Vitamin C has antioxidant, neuroprotective, and neuromodulating effects. Recently, it showed antinociceptive effect as a result of the antioxidant properties. Therefore, we designed this study to assess the effect of intravenous vitamin C on opiate consumption and pain in patients undergoing laparoscopic colectomy. Methods. A total of 100 patients were enrolled and allocated to receive 50 mg/kg vitamin C or placebo by intravenous infusion immediately after induction of anesthesia. Morphine consumption and scores of pain were assessed at 2, 6, and 24 h after completion of surgery. Results. There were 97 patients included in the analysis. Patients who received vitamin C had higher plasma concentrations of vitamin C at the end of surgery, significantly lower morphine consumption at the 2 h after end of surgery, and significantly lower pain scores at rest during first 24 h postoperatively. There was no significant difference between groups in side effects, fatigue score, or pain score during cough. Conclusion. This study shows high dose vitamin C infusion decreased postoperative pain during the first 24 h and reduced morphine consumption in the early postoperative period. Additional research needed to examine whether higher doses of vitamin C and longer infusion times can amplify these effects.

Vitamin C Deficiency Causes Severe Defects in the Development of the Neonatal Cerebellum and in the Motor Behaviors of Gulo(-/-) Mice

AIMS

The developing brain of a neonate is particularly susceptible to damage by vitamin C deficiency because of its rapid growth and immature antioxidant system. Cognitive impairment and sensory motor deficits are found in the adult brain upon vitamin C deficiency. Therefore, the aim of this study was to clarify the role of vitamin C in its own right and its related mechanisms in Gulo(-/-) mice incapable of synthesizing vitamin C.

RESULTS

When vitamin C supplementation was ceased for 2 weeks until delivery, stillbirths and a significant reduction in neonatal mice were observed and the growth of neonates was remarkably decreased. In addition, intraparenchymal hemorrhages were found in most of the brains, especially in the stillborn neonates. In addition, the levels of malondialdehyde (MDA) and 8-isoprostanes were increased and structural abnormalities were found in the cortex, hippocampus, and cerebellum. Especially, vitamin C deficiency caused the failure of or a delay in the formation of cerebellar fissures accompanied by abnormal foliation and altered Purkinje cell alignment. In the developed adult brains from vitamin C-deficient Gulo(-/-) mice, the levels of glutathione, MDA, nitrate, IL-6, TNF-α, and Bax were increased and the expression of the GABRA6 and calbindin-28k was decreased. Due to atrophy of the granule and Purkinje cells, the motor behavior of vitamin C-deficient Gulo(-/-) mice declined.

INNOVATION AND CONCLUSION

Vitamin C deficiency during gestation induces intraparenchymal hemorrhages and severe defects in the development of the cerebellum. In fully developed brains, it induces the functional impairment by altering the cellular composition in the cerebellum.

Sodium-dependent vitamin C transporter-2 mediates vitamin C transport at the cortical nerve terminal

It has been shown that vitamin C (VC) is transported at synaptic boutons, but how this occurs has not been elucidated. This study investigates the role of the sodium-dependent vitamin C transporter-2 (SVCT2) in transporting VC at the cortical nerve terminal. Immunostaining of cultured mouse superior cervical ganglion cells showed the SVCT2 to be expressed in presynaptic boutons, colocalizing with the vesicular monoamine transporter-2 and the norepinephrine transporter. Immunoblotting of enriched cortical synaptosomes demonstrated that the SVCT2 was enriched in presynaptic fractions, confirming a predominantly presynaptic location. In crude synaptosomes, known inhibitors of SVCT2 inhibited uptake of VC. Furthermore, the kinetic features of VC uptake were consistent with SVCT2-mediated function. VC was also found to efflux from synaptosomes by a mechanism not involving the SVCT2. Indeed, VC efflux was substantially offset by reuptake of VC on the SVCT2. The presence and function of the SVCT2 at the presynaptic nerve terminal suggest that it is the transporter responsible for recovery of VC released into the synaptic cleft.

Hippocampal memory enhancing activity of pine needle extract against scopolamine-induced amnesia in a mouse model

We evaluated the neuropharmacological effects of 30% ethanolic pine needle extract (PNE) on memory impairment caused by scopolamine injection in mice hippocampus. Mice were orally pretreated with PNE (25, 50, and 100 mg/kg) or tacrine (10 mg/kg) for 7 days, and scopolamine (2 mg/kg) was injected intraperitoneally, 30 min before the Morris water maze task on first day. To evaluate memory function, the Morris water maze task was performed for 5 days consecutively. Scopolamine increased the escape latency and cumulative path-length but decreases the time spent in target quadrant, which were ameliorated by pretreatment with PNE. Oxidant-antioxidant balance, acetylcholinesterase activity, neurogenesis and their connecting pathway were abnormally altered by scopolamine in hippocampus and/or sera, while those alterations were recovered by pretreatment with PNE. As lipid peroxidation, 4HNE-positive stained cells were ameliorated in hippocampus pretreated with PNE. Pretreatment with PNE increased the proliferating cells and immature neurons against hippocampal neurogenesis suppressed by scopolamine, which was confirmed by ki67- and DCX-positive stained cells. The expression of brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element-binding protein (pCREB) in both protein and gene were facilitated by PNE pretreatment. These findings suggest that PNE could be a potent neuropharmacological drug against amnesia, and its possible mechanism might be modulating cholinergic activity via CREB-BDNF pathway.

Vitamin C deficiency in the brain impairs cognition, increases amyloid accumulation and deposition, and oxidative stress in APP/PSEN1 and normally aging mice

Subclinical vitamin C deficiency is widespread in many populations, but its role in both Alzheimer's disease and normal aging is understudied. In the present study, we decreased brain vitamin C in the APPSWE/PSEN1deltaE9 mouse model of Alzheimer's disease by crossing APP/PSEN1(+) bigenic mice with SVCT2(+/-) heterozygous knockout mice, which have lower numbers of the sodium-dependent vitamin C transporter required for neuronal vitamin C transport. SVCT2(+/-) mice performed less well on the rotarod task at both 5 and 12 months of age compared to littermates. SVCT2(+/-) and APP/PSEN1(+) mice and the combination genotype SVCT2(+/-)APP/PSEN1(+) were also impaired on multiple tests of cognitive ability (olfactory memory task, Y-maze alternation, conditioned fear, Morris water maze). In younger mice, both low vitamin C (SVCT2(+/-)) and APP/PSEN1 mutations increased brain cortex oxidative stress (malondialdehyde, protein carbonyls, F2-isoprostanes) and decreased total glutathione compared to wild-type controls. SVCT2(+/-) mice also had increased amounts of both soluble and insoluble Aβ1-42 and a higher Aβ1-42/1-40 ratio. By 14 months of age, oxidative stress levels were similar among groups, but there were more amyloid-β plaque deposits in both hippocampus and cortex of SVCT2(+/-)APP/PSEN1(+) mice compared to APP/PSEN1(+) mice with normal brain vitamin C. These data suggest that even moderate intracellular vitamin C deficiency plays an important role in accelerating amyloid pathogenesis, particularly during early stages of disease development, and that these effects are likely modulated by oxidative stress pathways.

Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer's disease

Seizures are a known co-occurring symptom of Alzheimer's disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer's disease and epilepsy. The purpose of this study was to test whether mice that have diminished brain ascorbic acid in addition to carrying human Alzheimer's disease mutations in the amyloid precursor protein (APP) and presenilin 1 (PSEN1) genes, had altered electrical activity in the brain (electroencephalography; EEG), and were more susceptible to pharmacologically induced seizures. Brain ascorbic acid was decreased in APP/PSEN1 mice by crossing them with sodium vitamin C transporter 2 (SVCT2) heterozygous knockout mice. These mice have an approximately 30% decrease in brain ascorbic acid due to lower levels of SVCT2 that supplies the brain with ASC. SVCT2+/-APP/PSEN1 mice had decreased ascorbic acid and increased oxidative stress in brain, increased mortality, faster seizure onset latency following treatment with kainic acid (10 mg/kg i.p.), and more ictal events following pentylenetetrazol (50 mg/kg i.p.) treatment. Furthermore, we report the entirely novel phenomenon that ascorbic acid deficiency alone increased the severity of kainic acid- and pentylenetetrazol-induced seizures. These data suggest that avoiding ascorbic acid deficiency may be particularly important in populations at increased risk for epilepsy and seizures, such as Alzheimer's disease.

Non-enzymatic cyclic oxygenated metabolites of adrenic, docosahexaenoic, eicosapentaenoic and α-linolenic acids; bioactivities and potential use as biomarkers

Cyclic oxygenated metabolites are formed in vivo through non-enzymatic free radical reaction of n-6 and n-3 polyunsaturated fatty acids (PUFAs) such as arachidonic (ARA C20:4 n-6), adrenic (AdA 22:4 n-6), α-linolenic (ALA 18:3 n-3), eicosapentaenoic (EPA 20:5 n-3) and docosahexaenoic (DHA 22:6 n-3) acids. These cyclic compounds are known as isoprostanes, neuroprostanes, dihomo-isoprostanes and phytoprostanes. Evidence has emerged for their use as biomarkers of oxidative stress and, more recently, the n-3PUFA-derived compounds have been shown to mediate bioactivities as secondary messengers. Accordingly, this review will focus on the cyclic oxygenated metabolites generated from AdA, ALA, EPA and DHA. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".

Potato chip intake increases ascorbic acid levels and decreases reactive oxygen species in SMP30/GNL knockout mouse tissues

Potato chips (PC) contain abundant amounts of the free radical scavenger ascorbic acid (AA) due to the rapid dehydration of potato tubers (Solanum tuberosum) that occurs during frying. To evaluate the antioxidant activity of PC, this study examined reactive oxygen species (ROS) levels in tissues from SMP30/GNL knockout (KO) mice that cannot synthesize AA and determined AA and ROS levels after the animals were fed 20 and 10% PC diets for 7 weeks. Compared with AA-sufficient mice, AA-depleted SMP30/GNL KO mice showed high ROS levels in tissues. SMP30/GNL KO mice fed a PC diet showed high AA and low ROS levels in the brain, heart, lung, testis, soleus muscle, plantaris muscle, stomach, small intestine, large intestine, eyeball, and epididymal fat compared with AA-depleted mice. The data suggest that PC intake increases AA levels and enhances ROS scavenging activity in tissues of SMP30/GNL KO mice, which are a promising model for evaluating the antioxidant activity of foods.

Does vitamin C deficiency affect cognitive development and function?

Vitamin C is a pivotal antioxidant in the brain and has been reported to have numerous functions, including reactive oxygen species scavenging, neuromodulation, and involvement in angiogenesis. Absence of vitamin C in the brain has been shown to be detrimental to survival in newborn SVCT2(−/−) mice and perinatal deficiency have shown to reduce hippocampal volume and neuron number and cause decreased spatial cognition in guinea pigs, suggesting that maternal vitamin C deficiency could have severe consequences for the offspring. Furthermore, vitamin C deficiency has been proposed to play a role in age-related cognitive decline and in stroke risk and severity. The present review discusses the available literature on effects of vitamin C deficiency on the developing and aging brain with particular focus on in vivo experimentation and clinical studies.

Neuropsychiatric scurvy

BACKGROUND

Scurvy is a disease with well-known peripheral symptoms, such as bleeding and pain.

METHODS

The clinical and historical evidence for a distinct form of scurvy affecting the central nervous system, called neuropsychiatric scurvy, is reviewed. Pathophysiologic factors are described, as well as its diagnosis and management.

Ethanol extract of Astragali Radix and Salviae Miltiorrhizae Radix, Myelophil, exerts anti-amnesic effect in a mouse model of scopolamine-induced memory deficits

ETHNOPHARMACOLOGICAL RELEVANCE

Myelophil, a combination of extracts taken from Astragali Radix and Salviae Miltiorrhizae Radix, is a traditional Chinese medicine used for the treatment of chronic fatigue-associated disorders. Here we examined the ability of Myelophil to alleviate memory impairment in a mouse model. We aimed to investigate whether Myelophil has the pharmacological effects on memory deficits associated with brain dysfunctions using an animal model.

MATERIALS AND METHODS

Ten week-old male C57BL/6N mice were pretreated with Myelophil (50, 100, or 200 mg/kg), or tacrine (10 mg/kg) for 7 days, and then intraperitoneally injected with scopolamine (1 mg/kg). Memory-related behaviors were evaluated using the Morris water maze for 5 days. Levels of biomarkers of oxidative stress, antioxidant activity, acetylcholinesterase (AChE) activity, and extracellular signal-regulated kinase (ERK) were measured in brain tissues.

RESULTS

Scopolamine treatment increased the escape latency time and shortened time spent in the target quadrant; these effects were ameliorated by pretreatment with Myelophil. Scopolamine-induced changes in reactive oxygen species (ROS), malondialehyde (MDA), and AChE activity were significantly attenuated in mice pretreated with Myelophil. Recovery of antioxidant capacities, including total glutathione (GSH) content, and the activities of GSH-reductase, GSH-S-transferase, and catalase was also evident in Myelophil-treated mice. The strongest effects were seen for ERK and muscarinic acetylcholine receptor 1 (mAChR1) at both the protein and gene expression levels, with significant amelioration of expression levels in the Myelophil pretreatment group.

CONCLUSIONS

These results suggest that Myelophil confers anti-amnesic properties in a mouse model of memory impairment, driven in part by the modulation of cholinergic activity.

Chronic vitamin C deficiency promotes redox imbalance in the brain but does not alter sodium-dependent vitamin C transporter 2 expression

Vitamin C (VitC) has several roles in the brain acting both as a specific and non-specific antioxidant. The brain upholds a very high VitC concentration and is able to preferentially retain VitC even during deficiency. The accumulation of brain VitC levels much higher than in blood is primarily achieved by the sodium dependent VitC transporter (SVCT2). This study investigated the effects of chronic pre-and postnatal VitC deficiency as well as the effects of postnatal VitC repletion, on brain SVCT2 expression and markers of oxidative stress in young guinea pigs. Biochemical analyses demonstrated significantly decreased total VitC and an increased percentage of dehydroascorbic acid, as well as increased lipid oxidation (malondialdehyde), in the brains of VitC deficient animals (p < 0.0001) compared to controls. VitC repleted animals were not significantly different from controls. No significant changes were detected in either gene or protein expression of SVCT2 between groups or brain regions. In conclusion, chronic pre-and postnatal VitC deficiency increased brain redox imbalance but did not increase SVCT2 expression. Our findings show potential implications for VitC deficiency induced negative effects of redox imbalance in the brain and provide novel insight to the regulation of VitC in the brain during deficiency.

Ascorbic acid and the brain: rationale for the use against cognitive decline

This review is focused upon the role of ascorbic acid (AA, vitamin C) in the promotion of healthy brain aging. Particular attention is attributed to the biochemistry and neuronal metabolism interface, transport across tissues, animal models that are useful for this area of research, and the human studies that implicate AA in the continuum between normal cognitive aging and age-related cognitive decline up to Alzheimer’s disease. Vascular risk factors and comorbidity relationships with cognitive decline and AA are discussed to facilitate strategies for advancing AA research in the area of brain health and neurodegeneration.

Abnormal vibrissa-related behavior and loss of barrel field inhibitory neurons in 5xFAD transgenics

A recent study reported lower anxiety in the 5xFAD transgenic mouse model of Alzheimer's disease, as measured by reduced time on the open arms of an elevated plus maze. This is important because all behaviors in experimental animals must be interpreted in light of basal anxiety and response to novel environments. We conducted a comprehensive anxiety battery in the 5xFAD transgenics and replicated the plus-maze phenotype. However, we found that it did not reflect reduced anxiety, but rather abnormal avoidance of the closed arms on the part of transgenics and within-session habituation to the closed arms on the part of wild-type controls. We noticed that the 5xFAD transgenics did not engage in the whisker-barbering behavior typical of mice of this background strain. This is suggestive of abnormal social behavior, and we suspected it might be related to their avoidance of the closed arms on the plus maze. Indeed, transgenic mice exhibited excessive home-cage social behavior and impaired social recognition, and did not permit barbering by wild-type mice when pair-housed. When their whiskers were snipped the 5xFAD transgenics no longer avoided the closed arms on the plus maze. Examination of parvalbumin (PV) staining showed a 28.9% reduction in PV+ inhibitory interneurons in the barrel fields of 5xFAD mice, and loss of PV+ fibers in layers IV and V. This loss of vibrissal inhibition suggests a putatively aversive overstimulation that may be responsible for the transgenics' avoidance of the closed arms in the plus maze.

Oxidative imbalance and anxiety disorders

The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies.

Antioxidant supplementation ameliorates molecular deficits in Smith-Lemli-Opitz syndrome

BACKGROUND

Smith-Lemli-Opitz syndrome (SLOS) is an inborn error of cholesterol biosynthesis characterized by diminished cholesterol and increased 7-dehydrocholesterol (7-DHC) levels. 7-Dehydrocholesterol is highly reactive, giving rise to biologically active oxysterols.

METHODS

7-DHC-derived oxysterols were measured in fibroblasts from SLOS patients and an in vivo SLOS rodent model using high-performance liquid chromatography tandem mass spectrometry. Expression of lipid biosynthesis genes was ascertained by quantitative polymerase chain reaction and Western blot. The effects of an antioxidant mixture of vitamin A, coenzyme Q10, vitamin C, and vitamin E were evaluated for their potential to reduce formation of 7-DHC oxysterols in fibroblast from SLOS patients. Finally, the effect of maternal feeding of vitamin E enriched diet was ascertained in the brain and liver of newborn SLOS mice.

RESULTS

In cultured human SLOS fibroblasts, the antioxidant mixture led to decreased levels of the 7-DHC-derived oxysterol, 3β,5α-dihydroxycholest-7-en-6-one. Furthermore, gene expression changes in SLOS human fibroblasts were normalized with antioxidant treatment. The active ingredient appeared to be vitamin E, as even at low concentrations, it significantly decreased 3β,5α-dihydroxycholest-7-en-6-one levels. In addition, analyzing a mouse SLOS model revealed that feeding a vitamin E enriched diet to pregnant female mice led to a decrease in oxysterol formation in brain and liver tissues of the newborn Dhcr7-knockout pups.

CONCLUSIONS

Considering the adverse effects of 7-DHC-derived oxysterols in neuronal and glial cultures and the positive effects of antioxidants in patient cell cultures and the transgenic mouse model, we believe that preventing formation of 7-DHC oxysterols is critical for countering the detrimental effects of DHCR7 mutations.

Stereological studies of the effects of sodium benzoate or ascorbic acid on rats` cerebellum

OBJECTIVES

To evaluate the cerebellar structure in sodium benzoate (NaB) or ascorbic acid (AA) treated rats.

METHODS

This experimental study was conducted between May and September 2013 in the Laboratory Animal Center of Shiraz University of Medical Sciences, Shiraz, Iran. The rats received distilled either water, NaB (200mg/kg/day), AA (100mg/kg/day), or NaB+AA. The hemispheres were removed after 28 days and underwent quantitative study.

RESULTS

The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei; the total number of the Purkinje, Bergman, granule, neurons, and glial cells of the molecular layer; and neurons and glial cells of the intracerebellar nuclei reduced by 21-52% in the NaB-treated rats compared with the distilled water group (p=0.004). The total number of the Purkinje, Bergman, Golgi, and granule cells was 29-45% higher in the AA-treated rats compared with the distilled water group (p=0.05). However, these measures reduced by 17-50% in the NaB+AA-treated rats compared with the distilled water group (p=0.004). The NaB+AA group did not induce any significant structural changes in comparison with the NaB group (p&gt;0.05).

CONCLUSIONS

The NaB exposure with or without AA treatment could alter the cerebellum. Yet, AA could prevent the loss of some cells in the cerebellum. 

Ascorbic acid prevents protein oxidation in livers of senescence marker protein-30/gluconolactonase knockout mice

AIM

Senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice are incapable of synthesizing L-ascorbic acid (AA) in vivo. As AA is known to be a water-soluble anti-oxidant, we assessed protein oxidation levels in livers from SMP30/GNL KO mice maintained in an AA-insufficient condition.

METHODS

Livers were collected from male SMP30/GNL KO mice at the ages of 3, 6 and 12 months, and wild-type (WT) mice at the ages of 3, 6, 12 and 24 months. To assess protein oxidation, we measured the content of protein carbonyl, which is a major protein oxidation marker. AA levels were measured by 2,4-dinitrophenylhydrazine method using high-performance liquid chromatography.

RESULTS

Livers of SMP30/GNL KO mice had just ∼5% as much AA as those of WT mice from 3 to 12 months-of-age. Protein carbonyl levels in livers from SMP30/GNL KO mice were a significant 1.8- to 2.3-fold higher than those from age-atched WT mice. To establish that the AA-insufficiency caused this difference, we added AA to some drinking water, and examined the effect on AA and protein carbonyl levels in livers from SMP30/GNL KO and WT mice. Livers from SMP30/GNL KO mice given extra AA had a significantly higher content than those from their deprived counterparts. Furthermore, protein carbonyl levels in livers from AA-supplemented SMP30/GNL KO mice were significantly lower than those from the SMP30/GNL KO mice without AA supplementation. However, added AA did not affect the protein carbonyl levels in WT mice.

CONCLUSIONS

These results strongly suggest that AA plays an important role in preventing protein oxidation in vivo, thus enhancing overall health.

Attenuation of sepsis-induced organ injury in mice by vitamin C

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is the principal cause of death in patients with sepsis. Recent work supports the notion that parenteral vitamin C (VitC) is protective in sepsis through pleiotropic mechanisms. Whether suboptimal levels of circulating VitC increase susceptibility to sepsis-induced MODS is unknown.

MATERIALS AND METHODS

Unlike mice, humans lack the ability to synthesize VitC because of loss of L-gulono-γ-lactone oxidase (Gulo), the final enzyme in the biosynthesis of VitC. To examine whether physiological levels of VitC are required for defense against a catastrophic infection, we induced sepsis in VitC sufficient and VitC deficient Gulo(-/-) mice by intraperitoneal infusion of a fecal stem solution (FIP). Some VitC deficient Gulo(-/-) mice received a parenteral infusion of ascorbic acid (AscA, 200 mg/kg) 30 minutes after induction of FIP. We used molecular, histological, and biochemical analyses to assess for MODS as well as abnormalities in the coagulation system and circulating blood cells.

RESULTS

FIP produced injury to lungs, kidneys and liver (MODS) in VitC deficient Gulo(-/-) mice. MODS was not evident in FIP-exposed VitC sufficient Gulo(-/-) mice and attenuated in VitC deficient Gulo(-/-) mice infused with AscA. Septic VitC deficient Gulo(-/-) mice developed significant abnormalities in the coagulation system and circulating blood cells. These were attenuated by VitC sufficiency/infusion in septic Gulo(-/-) mice.

CONCLUSIONS

VitC deficient Gulo(-/-) mice were more susceptible to sepsis-induced MODS. VitC sufficiency or parenteral infusion of VitC, following induction of sepsis, normalized physiological functions that attenuated the development of MODS in sepsis.

Behavioral and serotonergic response changes in the Dhcr7-HET mouse model of Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is a developmental disorder resulting from mutations to the Dhcr7 gene, which is required for cholesterol synthesis. Patients with SLOS typically exhibit a number of severe behavioral deficits and many are diagnosed with autistic spectrum disorder. Although the molecular pathophysiology underlying behavioral changes in SLOS and autism spectrum disorders is poorly understood, there is evidence for the involvement of the serotonergic system in SLOS and autism in general. Behavioral testing was undertaken to ascertain the basal behavioral differences between Dhcr7-heterozygous (HET) and wild-type control mice and explore the utility of a Dhcr7-HET mouse line in the development of new treatments for this disorder. Dhcr7-HET mice did not differ from wild-type control mice on basic measures of locomotor activity, anxiety and neuromuscular ability. However, female Dhcr7-HET mice at 6 months of age or older were significantly more likely to win on the social dominance tube test against an unfamiliar mouse. Pharmacological testing, using the 5-HT2A agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), showed increased head-twitch response in Dhcr7-HET mice, which was apparent from 6 months of age. No differences were found between the genotypes in testing for 5-HT1A agonist 8-OH-DPAT-induced hypothermia. These data indicate an underlying dysfunction of the 5-HT2A receptors in Dhcr7-HET mice that warrants further investigation to establish how this may relate to behavioral disturbances in human patients carrying Dhcr7 mutations.