α-Lipoic acid (LA) enantiomers protect SH-SY5Y cells against glutathione depletion

Cadmium neurotoxicity and therapeutic strategies

Cadmium (Cd) is a multitarget, carcinogenic, nonessential environmental pollutant. Due to its toxic effects at very low concentrations, lengthy biological half-life, and low excretion rate, exposure to Cd carries a concern. Prolonged exposure to Cd causes severe injury to the nervous system of both humans and animals. Nevertheless, the precise mechanisms responsible for the neurotoxic effects of Cd have yet to be fully elucidated. The accurate chemical mechanism potentially entails the destruction of metal-ion homeostasis, inducing oxidative stress, apoptosis, and autophagy. Here we review the evidence of the neurotoxic effects of Cd and corresponding strategies to protect against Cd-induced central nervous system injury.

Protective effects of alpha-lipoic acid on anxiety-like behavior, memory and prevention of hippocampal oxidative stress in methamphetamine-treated rats

RATIONALE

Alpha-lipoic acid is an essential cofactor for aerobic metabolism and acts as a potent antioxidant in the body. It has been shown that acute exposure to methamphetamine induces oxidative stress, which is responsible for severe cognitive deficits in animals. The hippocampus plays a crucial role in the processing of memory and anxiety-like behavior.

OBJECTIVES

In this study, preventive effect of the alpha-lipoic acid on memory impairment in methamphetamine-induced neurotoxicity was investigated.

METHODS

Wistar male rats (200-220 g) were allocated to five groups (seven rats in each group): (1) saline + saline, (2) saline + vehicle (sunflower oil as alpha-lipoic acid solvent), (3) methamphetamine + vehicle, (4) methamphetamine + alpha-lipoic acid 10 mg/kg, and (5) methamphetamine + alpha-lipoic acid 40 mg/kg. Rats received intraperitoneal methamphetamine repeatedly (2 × 20 mg/kg, 2 h interval). Alpha-lipoic acid was injected 30 min, 24 h, and 48 h after the last injection of methamphetamine. The passive avoidance test and open field were used for evaluation of memory retrieval and anxiety, respectively. After behavioral test, rats were anesthetized, their brains were extracted, and after preparing hippocampal homogenates, malondialdehyde (MDA) level, catalase, and superoxide dismutase (SOD) activities were evaluated.

RESULTS

Statistical analysis showed that injection of saline or sunflower oil had no significant effect on anxiety, memory, or oxidative stress markers. Methamphetamine induced memory impairment, increased anxiety-like behavior and MDA level, but it reduced catalase and SOD activity. Treatment with alpha-lipoic acid decreased MDA, increased catalase and SOD activity, and also prevented memory impairment and anxiety-like behavior. Our results showed that alpha-lipoic acid protected the hippocampus from oxidative stress by elevating SOD and CAT activities and reduced memory impairment following acute methamphetamine injection. These findings suggest that alpha-lipoic acid may have a protective effect against the adverse effects of methamphetamine exposure on the hippocampus. Therefore, the current data indicated that ALA can reduce oxidative stress predominantly by its antioxidant property.

Seabra PS, Fonseca ADN, de Azevedo Sousa KM, de Oliveira SBB, Carneiro ADS, Coleman MD, Monteiro MC. Alpha-Lipoic Acid and Its Enantiomers Prevent Methemoglobin Formation and DNA Damage Induced by Dapsone Hydroxylamine: Molecular Mechanism and Antioxidant Action

Dapsone (DDS) therapy can frequently lead to hematological side effects, such as methemoglobinemia and DNA damage. In this study, we aim to evaluate the protective effect of racemic alpha lipoic acid (ALA) and its enantiomers on methemoglobin induction. The pre- and post-treatment of erythrocytes with ALA, ALA isomers, or MB (methylene blue), and treatment with DDS-NOH (apsone hydroxylamine) was performed to assess the protective and inhibiting effect on methemoglobin (MetHb) formation. Methemoglobin percentage and DNA damage caused by dapsone and its metabolites were also determined by the comet assay. We also evaluated oxidative parameters such as SOD, GSH, TEAC (Trolox equivalent antioxidant capacity) and MDA (malondialdehyde). In pretreatment, ALA showed the best protector effect in 2.5 µg/mL of DDS-NOH. ALA (1000 µM) was able to inhibit the induced MetHb formation even at the highest concentrations of DDS-NOH. All ALA tested concentrations (100 and 1000 µM) were able to inhibit ROS and CAT activity, and induced increases in GSH production. ALA also showed an effect on DNA damage induced by DDS-NOH (2.5 µg/mL). Both isomers were able to inhibit MetHb formation and the S-ALA was able to elevate GSH levels by stimulating the production of this antioxidant. In post-treatment with the R-ALA, this enantiomer inhibited MetHb formation and increased GSH levels. The pretreatment with R-ALA or S-ALA prevented the increase in SOD and decrease in TEAC, while R-ALA decreased the levels of MDA; and this pretreatment with R-ALA or S-ALA showed the effect of ALA enantiomers on DNA damage. These data show that ALA can be used in future therapies in patients who use dapsone chronically, including leprosy patients.

R- Is Superior to S-Form of α-Lipoic Acid in Anti-Inflammatory and Antioxidant Effects in Laying Hens

The development of single enantiomers with high efficiency and low toxic activity has become a hot spot for the development and application of drugs and active additives. The aim of the present study was to investigate the effectiveness of the application of α-lipoic acid with a different optical rotation to alleviate the inflammation response and oxidative stress induced by oxidized fish oil in laying hens. Sixty-four 124-week-old Peking Red laying hens were randomly allocated to four groups with eight replicates of two birds each. The normal group was fed basal diets supplemented with 1% fresh fish oil (FO), and the oxidative stress model group was constructed with diets supplemented with 1% oxidized fish oil (OFO). The two treatment groups were the S-form of the α-lipoic acid model with 1% oxidized fish oil (OFO + S-LA) and the R-form of the α-lipoic acid model with 1% oxidized fish oil (OFO + R-LA) added at 100 mg/kg, respectively. Herein, these results were evaluated by the breeding performance, immunoglobulin, immune response, estrogen secretion, antioxidant factors of the serum and oviduct, and pathological observation of the uterus part of the oviduct. From the results, diets supplemented with oxidized fish oil can be relatively successful in constructing a model of inflammation and oxidative stress. The OFO group significantly increased the levels of the serum inflammatory factor (TNF-α, IL-1β, IL-6, and IFN-γ) and the oxidative factor MDA and decreased the activity of the antioxidant enzyme (T-AOC, T-SOD, GSH-Px, GSH, and CAT) in the oviduct. The addition of both S-LA and R-LA significantly reduced the levels of serum inflammatory factors (TNF-α, IL-1β, IL-6, and IFN-γ), increased the activity of antioxidant indexes (T-AOC, T-SOD, GSH-Px, GSH, and CAT), and decreased the MDA contents in the serum and oviduct. Meanwhile, the supplementation of S-LA and R-LA also mitigated the negative effects of the OFO on the immunoglobulins (IgA and IgM) and serum hormone levels (P and E2). In addition, it was worth noting that the R-LA was significantly more effective than the S-LA in some inflammatory (IL-1β) and antioxidant indices (T-SOD, GSH, and CAT). Above all, both S-LA and R-LA can alleviate the inflammation and oxidative damage caused by oxidative stress in aged laying hens, and R-LA is more effective than S-LA. Thus, these findings will provide basic data for the potential development of α-lipoic acid as a chiral dietary additive for laying hens.

The Use of Bioactive Compounds in Hyperglycemia- and Amyloid Fibrils-Induced Toxicity in Type 2 Diabetes and Alzheimer’s Disease

It has become increasingly apparent that defective insulin signaling may increase the risk for developing Alzheimer’s disease (AD), influence neurodegeneration through promotion of amyloid formation or by increasing inflammatory responses to intraneuronal β-amyloid. Recent work has demonstrated that hyperglycemia is linked to cognitive decline, with elevated levels of glucose causing oxidative stress in vulnerable tissues such as the brain. The ability of β-amyloid peptide to form β-sheet-rich aggregates and induce apoptosis has made amyloid fibrils a leading target for the development of novel pharmacotherapies used in managing and treatment of neuropathological conditions such as AD-related cognitive decline. Additionally, deposits of β-sheets folded amylin, a glucose homeostasis regulator, are also present in diabetic patients. Thus, therapeutic compounds capable of reducing intracellular protein aggregation in models of neurodegenerative disorders may prove useful in ameliorating type 2 diabetes mellitus symptoms. Furthermore, both diabetes and neurodegenerative conditions, such as AD, are characterized by chronic inflammatory responses accompanied by the presence of dysregulated inflammatory biomarkers. This review presents current evidence describing the role of various small bioactive molecules known to ameliorate amyloidosis and subsequent effects in prevention and development of diabetes and AD. It also highlights the potential efficacy of peptide–drug conjugates capable of targeting intracellular targets.

Enantioselective Synthesis and Pharmacological Evaluation of Aza-CGP37157–Lipoic Acid Hybrids for the Treatment of Alzheimer’s Disease

Hybrids based on an aza-analogue of CGP37157, a mitochondrial Na⁺/Ca²⁺ exchanger antagonist, and lipoic acid were obtained in order to combine in a single molecule the antioxidant and NRF2 induction properties of lipoic acid and the neuroprotective activity of CGP37157. The four possible enantiomers of the hybrid structure were synthesized by using as the key step a fully diastereoselective reduction induced by Ellman’s chiral auxiliary. After computational druggability studies that predicted good ADME profiles and blood–brain permeation for all compounds, the DPPH assay showed moderate oxidant scavenger capacity. Following a cytotoxicity evaluation that proved the compounds to be non-neurotoxic at the concentrations tested, they were assayed for NRF2 induction capacity and for anti-inflammatory properties and measured by their ability to inhibit nitrite production in the lipopolysaccharide-stimulated BV2 microglial cell model. Moreover, the compounds were studied for their neuroprotective effect in a model of oxidative stress achieved by treatment of SH-SY5Y neuroblastoma cells with the rotenone–oligomycin combination and also in a model of hyperphosphorylation induced by treatment with okadaic acid. The stereocenter configuration showed a critical influence in NRF2 induction properties, and also in the neuroprotection against oxidative stress experiment, leading to the identification of the compound with S and R configuration as an interesting hit with a good neuroprotective profile against oxidative stress and hyperphosphorylation, together with a relevant anti-neuroinflammatory activity. This interesting multitarget profile will be further characterized in future work.

Aza-CGP37157-lipoic hybrids designed as novel Nrf2-inducers and antioxidants exert neuroprotection against oxidative stress and show neuroinflammation inhibitory properties

Two multitarget hybrids, derived from an aza-analogue of CGP37157, a mitochondrial Na⁺ /Ca²⁺ exchanger antagonist, and lipoic acid were designed in order to combine in a single molecule the antioxidant and Nrf2 induction properties of lipoic acid and the neuroprotective activity of CGP37157. The hybrid derivatives showed Nrf2 induction and radical scavenging properties, leading to a good neuroprotective profile against oxidative stress, together with an interesting antineuroinflammatory activity. The results obtained show differences in activity depending on the configuration of the chiral center of LA.

Establishment of Nrf2-deficient HaCaT and immortalized primary human foreskin keratinocytes and characterization of their responses to ROS-induced cytotoxicity

Nuclear factor erythroid 2-like 2 (Nrf2) is a key transcription factor responsible for the induction of cytoprotective genes when a cell is exposed to reactive oxygen species (ROS). Insufficient ROS neutralization has been associated with undesirable changes in the skin caused by age and disease. In order to mimic the pathological conditions of these oxidative stress-induced skin disorders, we established Nrf2-deficient HaCaT and immortalized human foreskin keratinocyte (iHFK) cell lines via lentiviral transduction of Nrf2-targeting short-hairpin RNAs. Their transcriptional, as well as translational blockage of Nrf2 expression, was verified by using a proteasomal inhibitor (MG132) and well-known Nrf2 activator (α-lipoic acid (ALA)). Reduced expression of NADPH dehydrogenase quinone 1 (NQO-1) and heme oxygenase 1 (HO-1) genes, which are well-characterized downstream targets of Nrf2-mediated transactivation, was also confirmed by using ALA and another Nrf2 activator, marliolide. In general, iHFK cells displayed more enhanced cytotoxicity to menadione, a ROS-generating reference compound, than HaCaT cells. In addition, the Nrf2 deficiency highly potentiated the cytotoxic effects of menadione in both HaCaT and iHFK cells. Interestingly, pretreatment of either ALA or marliolide conferred protection against the ROS induction and the subsequent development of cytotoxicity by menadione in both HaCaT and iHFK cells regardless of the Nrf2 status. These data suggest a possibility for activation of Nrf2-independent ROS detoxification pathways by either ALA or marliolide. These newly established Nrf2-deficient HaCaT and iHFK cell lines should be useful as a highly ROS-sensitive damaged skin model for the study of age-dependent cellular changes in an in vitro setting.

Mitochondrial Agents for Bipolar Disorder

Background

Bipolar disorder is a chronic and often debilitating illness. Current treatment options (both pharmaco- and psychotherapy) have shown efficacy, but for many leave a shortfall in recovery. Advances in the understanding of the pathophysiology of bipolar disorder suggest that interventions that target mitochondrial dysfunction may provide a therapeutic benefit.

Methods

This review explores the current and growing theoretical rationale as well as existing preclinical and clinical data for those therapies aiming to target the mitochondrion in bipolar disorder. A Clinicaltrials.gov and ANZCTR search was conducted for complete and ongoing trials on mitochondrial agents used in psychiatric disorders. A PubMed search was also conducted for literature published between January 1981 and July 2017. Systematic reviews, randomized controlled trials, observational studies, case series, and animal studies with an emphasis on agents affecting mitochondrial function and its role in bipolar disorder were included. The search was augmented by manually searching the references of key papers and related literature. The results were presented as a narrative review.

Results

Mitochondrial agents offer new horizons in mood disorder treatment. While some negative effects have been reported, most compounds are overall well tolerated and have generally benign side-effect profiles.

Conclusions

The study of neuroinflammation, neurodegeneration, and mitochondrial function has contributed the understanding of bipolar disorder's pathophysiology. Agents targeting these pathways could be a potential therapeutic strategy. Future directions include identification of novel candidate mitochondrial modulators as well as rigorous and well-powered clinical trials.

Potential Therapeutic Effects of Lipoic Acid on Memory Deficits Related to Aging and Neurodegeneration

The aging process comprises a series of organic alterations, affecting multiple systems, including the nervous system. Aging has been considered the main risk factor for the advance of neurodegenerative diseases, many of which are accompanied by cognitive impairment. Aged individuals show cognitive decline, which has been associated with oxidative stress, as well as mitochondrial, and consequently energetic failure. Lipoic acid (LA), a natural compound present in food and used as a dietary supplement, has been considered a promising agent for the treatment and/or prevention of neurodegenerative disorders. In spite of a number of preclinical studies showing beneficial effects of LA in memory functioning, and pointing to its neuroprotective potential effect, to date only a few studies have examined its effects in humans. Investigations performed in animal models of memory loss associated to aging and neurodegenerative disorders have shown that LA improves memory in a variety of behavioral paradigms. Moreover, cell and molecular mechanisms underlying LA effects have also been investigated. Accordingly, LA displays antioxidant, antiapoptotic, and anti-inflammatory properties in both in vivo and in vitro studies. In addition, it has been shown that LA reverses age-associated loss of neurotransmitters and their receptors, which can underlie its effects on cognitive functions. The present review article aimed at summarizing and discussing the main studies investigating the effects of LA on cognition as well as its cell and molecular effects, in order to improve the understanding of the therapeutic potential of LA on memory loss during aging and in patients suffering from neurodegenerative disorders, supporting the development of clinical trials with LA.

Efficacy of α-lipoic acid against cadmium toxicity on metal ion and oxidative imbalance, and expression of metallothionein and antioxidant genes in rabbit brain

To explore the protective efficacy of α-lipoic acid (ALA) against Cd-prompted neurotoxicity, young male New Zealand rabbits (Oryctolagus cuniculus) were divided randomly into four groups. Group 1 (control) received demineralized water. Group 2 (Cd) administered cadmium chloride (CdCl₂) 3 mg/kg bwt. Group 3 (ALA) administered ALA 100 mg/kg bwt. Group 4 (Cd + ALA) administered ALA 1 h after Cd. The treatments were administered orally for 30 consecutive days. Cd-induced marked disturbances in neurochemical parameters were indicated by the reduction in micro- and macro-elements (Zn, Fe, Cu, P, and Ca), with the highest reduction in Cd-exposed rabbits, followed by Cd + ALA group and then ALA group. In the brain tissues, Cd has significantly augmented the lipid hydroperoxides (LPO) and reduced the glutathione (GSH) and total antioxidant capacity (TAC), and glutathione peroxidase and glutathione S-transferase enzyme activities but had an insignificant effect on the antioxidant redox enzymes. Administration of ALA effectively restored LPO and sustained GSH and TAC contents. Moreover, Cd downregulated the transcriptional levels of Nrf2, MT3, and SOD1 genes, and upregulated that of Keap1 gene. ALA treatment, shortly following Cd exposure, downregulated Keap1, and upregulated Nrf2 and GPx1, while maintained MT3 and SOD1 mRNA gene expression in the rabbits' brain. These data indicated the ALA effectiveness in protecting against Cd-induced oxidative stress and the depletion of cellular antioxidants in the brain of rabbits perhaps due to its antioxidant, free radical scavenging, and chelating properties.

Alpha-Lipoic Acid Downregulates IL-1β and IL-6 by DNA Hypermethylation in SK-N-BE Neuroblastoma Cells

Alpha-lipoic acid (ALA) is a pleiotropic molecule with antioxidant and anti-inflammatory properties, of which the effects are exerted through the modulation of NF-kB. This nuclear factor, in fact, modulates different inflammatory cytokines, including IL-1b and IL-6, in different tissues and cell types. We recently showed that IL-1b and IL-6 DNA methylation is modulated in the brain of Alzheimer's disease patients, and that IL-1b expression is associated to DNA methylation in the brain of patients with tuberous sclerosis complex. These results prompted us to ask whether ALA-induced repression of IL-1b and IL-6 was dependent on DNA methylation. Therefore, we profiled DNA methylation in the 5'-flanking region of the two aforementioned genes in SK-N-BE human neuroblastoma cells cultured in presence of ALA 0.5 mM. Our experimental data pointed out that the two promoters are hypermethylated in cells supplemented with ALA, both at CpG and non-CpG sites. Moreover, the observed hypermethylation is associated with decreased mRNA expression and decreased cytokine release. These results reinforce previous findings indicating that IL-1b and IL-6 undergo DNA methylation-dependent modulation in neural models and pave the road to study the epigenetic mechanisms triggered by ALA.

Effect of Lipoic Acid on the Biochemical Mechanisms of Resistance to Bortezomib in SH-SY5Y Neuroblastoma Cells

Neuroblastoma (NB) is an extracranial solid cancer and the most common cancer in infancy. Despite the standard treatment for NB is based on the combination of chemotherapeutic drugs such as doxorubicin, vincristine, cyclophosphamide, and cisplatin, chemoresistance occurs over the time. The aim of the present research was to evaluate the effect of bortezomib (BTZ) (50 nM) on NB cell viability and how lipoic acid (ALA) (100 μM) modifies pharmacological response to this chemotherapeutic agent. Cell viability was assessed by ATP luminescence assay whereas expression of oxidative stress marker (i.e., heme oxygenase-1) and endoplasmic reticulum stress proteins was performed by real-time PCR, western blot, and immunofluorescence. Our data showed that BTZ treatment significantly reduced cell viability when compared to untreated cultures (about 40%). Interestingly, ALA significantly reduced the efficacy of BTZ (about 30%). Furthermore, BTZ significantly induced heme oxygenase-1 as a result of increased oxidative stress and such overexpression was prevented by concomitant treatment with ALA. Similarly, ALA significantly reduced BTZ-mediated endoplasmic reticulum stress as measured by reduction in BiP1 and IRE1α, ERO1α, and PDI expression. In conclusion, our data suggest that BTZ efficacy is dependent on cellular redox status and such mechanisms may be responsible of chemoresistance to this chemotherapeutic agent.

Protective Effects of Alpha-Lipoic Acid on Methotrexate-Induced Oxidative Lung Injury in Rats

OBJECTIVE

Oxidative stress is one of the major causes of methotrexate induced lung injury (MILI). Alpha-lipoic acid (ALA), which occurs naturally in human food, has antioxidative and anti-inflammatory activities. The aim of this study was to research the potential protective role of ALA on MILI in rats.

METHODS

Twenty one rats were randomly subdivided into three groups: control (group I), methotrexate (MTX) treated (group II), and MTX+ALA treated (group III). Lung injury was performed with a single dose of MTX (20 mg/kg) to groups 2 and 3. On the sixth day, animals in all groups were sacrificed by decapitation and lung tissue and blood samples were removed for histological examination and also measurement the levels of interleukin-1-beta (IL-1β), malondialdehyde (MDA), glutathione (GSH), tumour necrosis factor-alpha (TNF-α), myeloperoxidase (MPO), and sodium potassium-adenosine triphosphatase (Na+/K+ATPase).

RESULTS

In MTX group tissue GSH, Na+/K+ATPase activities were lower, tissue MDA, MPO and plasma IL-1?, TNF-? were significantly higher than the other groups. Histopathological examination showed that lung injury was less severe in group 2 according to group 3.

CONCLUSIONS

Oxidative damage of MTX in rat lung is partially reduced when combined with ALA.

Neuroprotection of Brain Cells by Lipoic Acid Treatment after Cellular Stress

We have previously observed that in vivo lipoic acid (LA) treatment induced a protective effect onto primary cortical neurons after brain injury. In an effort to better understand LA action mechanism in the brain, in the present study, we stressed brain cells in vitro and ex vivo and then analyzed by inmmunocytochemistry and biochemical assays, the changes induced by LA on cell survival and on the concentration of oxidative stress markers, such as glutathione (GSH), oxidized glutathione (GSSG), and malondialdehyde (MDA). The stressors used were lipopolysaccharide (LPS), dopamine, and l-buthionine-S,R-sulfoximine (BSO). Our results showed that LA decreased cell death and increased GSH/GSSG ratio in cells stressed by LPS + dopamine, suggesting that the mechanism underlying LA action is regeneration of GSSG to GSH. When cells were stressed by BSO, LA diminished cell death and decreased GSH/GSSG ratio. In this case, it could be concluded that, due to the low GSH basal levels, GSSG reduction is not possible and therefore it might be thought that cell death prevention might be mediated through other mechanisms. Finally, we induced chemical oxidative damage in brain homogenate. After LA treatment, GSH and GSH/GSSG ratio increased and MDA concentration decreased, demonstrating again that LA was not able to increase de novo GSH synthesis but is able to increase GSSG conversion to GSH.

Time Course Effect of R-Alpha-Lipoic Acid on Cellular Metabolomics in Cultured Hepatoma Cells

Alpha-lipoic acid (LA) is a powerful antioxidant. LA has two enantiomers, R(+)-LA (R-LA) and S(-)-LA (S-LA). Of these, R-LA is naturally occurring and an essential cofactor in energy metabolism. R-LA treatment has been reported to affect glucose metabolism in rat hepatoma cells. This study analyzed the time course of metabolite levels in LA-treated cultured H4IIEC3 rat hepatoma cells, including a specific evaluation of the effect of R-LA and the enantioselectivity of LA. Principal component analysis showed that this experiment was well designed to observe enantioselectivity. R-LA treatment was found to inhibit the glycolysis and Thr-Gly-Ser pathways, as well as lactic acid production, leading to the inhibition of gluconeogenesis in starved H4IIEC3 cells. This study may provide mechanistic insight into how R-LA induces apoptosis in hepatoma cells.

Effect of Novel Compound LX519290, a Derivative of l-allo Threonine, on Antioxidant Potential in Vitro and in Vivo

We investigated the antioxidative activity of LX519290, a derivative of l-allo threonine, in vitro and in vivo. To evaluate the antioxidative activity of LX519290, we performed several in vitro assays (2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical-scavenging assays, a ferric reducing antioxidant power assay, cupric-reducing antioxidant capacity, and oxygen radical absorbance capacity assay) and evaluated inhibition against the generation of nitric oxide (NO) and reactive oxygen species (ROS) in murine macrophage (RAW264.7) cells. The results showed that LX519290 possessed very strong radical scavenging activity and reducing power, and inhibited NO and ROS generation in a dose-dependent manner without showing any cytotoxicity. LX519290 treatment also increased the total thiol content and glutathione S-transferases (GST) activities in RAW264.7 cells. Finally, we also determined whether LX519290 affects the mRNA levels of antioxidant enzymes in vitro and in vivo. The expression of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were markedly higher in the sample-treated group than in the oxidative stress group. LX519290 treatment also increased the transcriptional and translational activities of NF-E2-related factor-2 (Nrf-2) with corresponding increases in the transcriptional and translational activities of haeme oxygenase-1 (HO-1). Collectively, the data demonstrated that LX519290 has potent antioxidative activity, decreases NO and ROS generation, increases total thiol content and GST activities in RAW264.7 cells, and increases the transcriptional and translational levels of antioxidant enzymes in vitro and in vivo.

An Involvement of PI3-K/Akt Activation and Inhibition of AIF Translocation in Neuroprotective Effects of Undecylenic Acid (UDA) Against Pro-Apoptotic Factors-Induced Cell Death in Human Neuroblastoma SH-SY5Y Cells

Undecylenic acid (UDA), a naturally occurring 11-carbon unsaturated fatty acid, has been used for several years as an economical antifungal agent and a nutritional supplement. Recently, the potential usefulness of UDA as a neuroprotective drug has been suggested based on the ability of this agent to inhibit μ-calpain activity. In order to verify neuroprotective potential of UDA, we tested protective efficacy of this compound against cell damage evoked by pro-apoptotic factors (staurosporine and doxorubicin) and oxidative stress (hydrogen peroxide) in human neuroblastoma SH-SY5Y cells. We showed that UDA partially protected SH-SY5Y cells against the staurosporine- and doxorubicin-evoked cell death; however, this effect was not connected with its influence on caspase-3 activity. UDA decreased the St-induced changes in mitochondrial and cytosolic AIF level, whereas in Dox-model it affected only the cytosolic AIF content. Moreover, UDA (1-40 μM) decreased the hydrogen peroxide-induced cell damage which was connected with attenuation of hydrogen peroxide-mediated necrotic (PI staining, ADP/ATP ratio) and apoptotic (mitochondrial membrane potential, caspase-3 activation, AIF translocation) changes. Finally, we demonstrated that an inhibitor of PI3-K/Akt (LY294002) but not MAPK/ERK1/2 (U0126) pathway blocked the protection mediated by UDA in all tested models of SH-SY5Y cell injury. These in vitro data point to UDA as potentially effective neuroprotectant the utility of which should be further validated in animal studies.

Ammonia-induced oxidative damage in neurons is prevented by resveratrol and lipoic acid with participation of heme oxygenase 1

Ammonia is a metabolite that, at high concentrations, is implicated in neurological disorders, such as hepatic encephalopathy (HE), which is associated with acute or chronic liver failure. Astrocytes are considered the primary target of ammonia toxicity in the central nervous system (CNS) because glutamine synthetase (GS), responsible for ammonia metabolism in CNS, is an astrocytic enzyme. Thus, neuronal dysfunction has been associated as secondary to astrocytic impairment. However, we demonstrated that ammonia can induce direct effects on neuronal cells. The cell viability was decreased by ammonia in SH-SY5Y cells and cerebellar granule neurons. In addition, ammonia induced increased reactive oxygen species (ROS) production and decreased GSH intracellular content, the main antioxidant in CNS. As ammonia neurotoxicity is strongly associated with oxidative stress, we also investigated the potential neuroprotective roles of the antioxidants, resveratrol (RSV) and lipoic acid (LA), against ammonia toxicity in cerebellar granule neurons. RSV and LA were able to prevent the oxidative damage induced by ammonia, maintaining the levels of ROS production and GSH close to basal values. Both antioxidants also decreased ROS production and increased GSH content under basal conditions (in the absence of ammonia). Moreover, we showed that heme oxygenase 1 (HO1), a protein associated with protection against stress conditions, is involved in the beneficial effects of RSV and LA in cerebellar granule neurons. Thus, this study reinforces the neuroprotective effects of RSV and LA. Although more studies in vivo are required, RSV and LA could represent interesting therapeutic strategies for the management of HE.

Anti-inflammatory effects of lipoic acid through inhibition of GSK-3β in lipopolysaccharide-induced BV-2 microglial cells

Activated microglial cells play an important role in immune and inflammatory responses in CNS and play a role in neurodegenerative diseases. We examined the effects of lipoic acid (LA) on inflammatory responses of BV-2 microglial cells activated by lipopolysaccharide (LPS), and explored the underlying mechanisms of action of LA. BV-2 cells treated with LPS showed an up-regulation of mRNA of the pro-inflammatory molecules, inducible nitric oxide synthase (iNOS). LA suppressed the expression of iNOS and furthermore, LPS-induced production of nitrite. Moreover, LA suppressed the nuclear translocation of RelA, a component of nuclear factor-kappa B (NF-κB) that contains transcriptional activator domain for LPS. The mechanisms of LA-mediated anti-inflammatory effects on microglia remain unknown, and we suggested an involvement of Akt/glycogen synthase kinase-3β (GSK-3β) phosphorylation. The results showed that inhibitor of phosphatidylinositol 3-kinase prevented LA-mediated suppression of LPS induction of RelA and expression of iNOS. Furthermore, these inflammatory actions were prevented by GSK-3β inhibitors. These data demonstrate a role for LA as a chemical modulator of inflammatory responses by microglia, and thus may be a therapeutic strategy for treating neurodegenerative diseases with an inflammatory component.

Tissue-specific upregulation of HSP72 in mice following short-term administration of alcohol

Oxidative stress and cellular injury have been implicated in induction of HSP72 by alcohol. We investigated the association between HSP72 induction and oxidative stress in mouse tissues following short-term administration of high doses of alcohol and caffeine alone or in combination. Adult male C57BL/6J mice were gavaged with vehicle, alcohol (∼1.7 g/kg/day), caffeine (∼44 mg/kg/day), or alcohol plus caffeine once daily for ten consecutive days. Upon completion of the treatments, tissues were collected for structural and biochemical analyses. Alcohol alone caused mild to moderate lesions in heart, liver, and gastrocnemius muscle. Similar structural changes were observed following administration of alcohol and caffeine combined. Alcohol administration also led to decreased glutathione levels in all three tissues and reduced plasma superoxide dismutase capacity. In contrast, alcohol and caffeine in combination reduced glutathione levels only in liver and gastrocnemius muscle and had no effect on plasma superoxide dismutase. Significant elevations in HSP72 protein and mRNA and in HSF1 protein levels were noted only in liver by alcohol alone or in combination with caffeine. No significant changes in morphology and HSP72 were detected in any tissues tested following administration of caffeine alone. These results suggest that a redox mechanism is involved in the structural impairment caused by short-term high-dose alcohol. Oxidative tissue injury by alcohol may not be associated with tissue HSP72 induction. Induction of HSP72 in liver by alcohol is mediated at both the transcriptional and translational levels.