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We have recently demonstrated that S-allylcysteine (SAC) induces protection on neurochemical, biochemical and behavioral markers of striatal damage in different neurotoxic animal models - including a murine model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridinium (MPTP) injection to mice - indicating that pro-oxidant reactions underlie neurotoxicity in these models (García et al. 2008). In this work we investigated whether SAC can protect the striatum of mice from the morphological alterations in the MPTP toxic model, and if this response is correlated with a reduction in pro-inflammatory cytokine tumor necrosis factor-[alpha] (TNF-[alpha]) and inducible nitric oxide synthase (iNOS) expressions, and further reduction in astrocyte activation (glial fibrillary acidic protein (GFAP) expression). The striatal tissue from MPTP injected animals (30mg/kg, i.p., x5 days) showed a significant degree of cell damage and enhanced immunoreactivities to GFAP, TNF-[alpha] and iNOS, as well as an enhanced number of apoptotic nuclei. Treatment of mice with SAC (120mg/kg, i.p., x5 days) in parallel to MPTP significantly reduced or prevented all these markers. Our results suggest that MPTP-induced morphological alterations recruit a pro-inflammatory component triggered by cytokine TNF-[alpha] release and nitric oxide formation, which is sensitive to the antioxidant properties of SAC. This antioxidant is an effective experimental tool to reduce the brain lesions associated with oxidative damage and inflammatory responses. [ABSTRACT FROM AUTHOR]

Neurological diseases comprise a group of heterogeneous disorders characterized by progressive brain dysfunction and cell death. In the next years, these diseases are expected to constitute a world-wide health problem. Because excitotoxicity and oxidative stress are involved in neurodegenerative diseases, it becomes relevant to describe pharmacological therapies designed to activate endogenous cytoprotective systems. Activation of transcription factor Nrf2 stimulates cytoprotective vitagenes involved in antioxidant defense. In this work, we investigated the ability of the antioxidant curcumin to induce transcription factor Nrf2 in a neurodegenerative model induced by quinolinic acid in rats. Animals were administered with curcumin (400 mg/kg, p.o.) for 10 days, and then intrastriatally infused with quinolinic acid (240 nmol) on day 10 of treatment. Curcumin prevented rotation behavior (6 days post-lesion), striatal morphological alterations (7 days post-lesion) and neurodegeneration (1 and 3 days post-lesion) induced by quinolinic acid. Curcumin also reduced quinolinic acid-induced oxidative stress (measured as protein carbonyl content) at 6 h post-lesion. The protective effects of curcumin were associated to its ability to prevent the quinolinic acid-induced decrease of striatal intra-nuclear Nrf2 levels (30 and 120 min post-lesion), and total superoxide dismutase and glutathione peroxidase activities (1 day post-lesion). Therefore, results of this study support the concept that neuroprotection induced by curcumin is associated with its ability to activate the Nrf2 cytoprotective pathway and to increase the total superoxide dismutase and glutathione peroxidase activities. [ABSTRACT FROM AUTHOR]

Stroke represents one of the main causes of death and disability in the world; despite this, pharmacological therapies against stroke remain insufficient. Ischemic stroke is the leading etiology of stroke. Different molecular mechanisms, such as excitotoxicity, oxidative stress, and inflammation, participate in cell death and tissue damage. At a preclinical level, different garlic compounds have been evaluated against these mechanisms. Additionally, there is evidence supporting the participation of garlic compounds in other mechanisms that contribute to brain tissue recovery, such as neuroplasticity. After ischemia, neuroplasticity is activated to recover cognitive and motor function. Some garlic-derived compounds and preparations have shown the ability to promote neuroplasticity under physiological conditions and, more importantly, in cerebral damage models. This work describes damage/repair mechanisms and the importance of garlic as a source of antioxidant and anti-inflammatory agents against damage. Moreover, we examine the less-explored neurotrophic properties of garlic, culminating in proposals and observations based on our review of the available information. The aim of the present study is to propose that garlic compounds and preparations could contribute to the treatment of ischemic stroke through their neurotrophic effects.

Quinolinic acid (QUIN) is an agonist of N-methyl-D-aspartate receptor (NMDAr) used to study the underlying mechanism of excitotoxicity in animal models. There is evidence indicating that impairment in autophagy at early times contributes to cellular damage in excitotoxicity; however, the status of autophagy in QUIN model on day 7 remains unexplored. In this study, the ultrastructural analysis of subcellular compartments and the status of autophagy, necroptosis, and apoptosis in the striatum of rats administered with QUIN (120 nmol and 240 nmol) was performed on day 7. QUIN induced circling behavior, neurodegeneration, and cellular damage; also, it promoted swollen mitochondrial crests, spherical-like morphology, and mitochondrial fragmentation; decreased ribosomal density in the rough endoplasmic reticulum; and altered the continuity of myelin sheaths in axons with separation of the compact lamellae. Furthermore, QUIN induced an increase and a decrease in ULK1 and p-70-S6K phosphorylation, respectively, suggesting autophagy activation; however, the increased microtubule-associated protein 1A/1B-light chain 3-II (LC3-II) and sequestosome-1/p62 (SQSTM1/p62), the coexistence of p62 and LC3 in the same structures, and the decrease in Beclin 1 and mature cathepsin D also indicates a blockage in autophagy flux. Additionally, QUIN administration increased tumor necrosis factor alpha (TNFα) and receptor-interacting protein kinase 3 (RIPK3) levels and its phosphorylation (p-RIPK3), as well as decreased B-cell lymphoma 2 (Bcl-2) and increased Bcl-2-associated X protein (Bax) levels and c-Jun N-terminal kinase (JNK) phosphorylation, suggesting an activation of necroptosis and apoptosis, respectively. These results suggest that QUIN activates the autophagy, but on day 7, it is blocked and organelle and cellular damage, neurodegeneration, and behavior alterations could be caused by necroptosis and apoptosis activation., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background and Objective: The antinociceptive effects of garlic have shown promise in treating different chronic diseases in humans, such as knee osteoarthritis, rheumatoid arthritis and peripheral arterial occlusive disease stage II. The most common garlic products are garlic powder (dried garlic), steam distilled garlic oils, garlic oil macerate and aged garlic extract. These commercial products contain organosulphur compounds (OSCs) that have been extensively evaluated in preclinical models and some clinical assays to treat different diseases against pain. In this review, we describe the importance of some bioactive compounds found in garlic and their role in treating pain., Materials & Methods: A systematic search of the literature in Dimensions, PubMed, Scopus, and Web of Science was performed. Terms and preselected keywords relating to garlic, its derivatives and organusulphure compounds in acute, chronic and neuropathic pain, were used to perform a systematic literature search. Two independent reviewers screened the papers for inclusion and assessed the methodological quality., Results & Discussion: The antinociceptive activity of garlic and its OSC is related to its antioxidant and anti-inflammatory properties, which may be explained by the ability to block the synthesis of PGs, pro-inflammatory cytokines and interferon-γ, by the reduction COX-2 activity and increasing the levels of anti-inflammatory cytokines. Besides, garlic extract is an activator of TRPA1 and TRPV1, where the principal responsible for this activation are OSC., Conclusion: The relationship between these pathways allows a better understanding how garlic and its derivates could be carrying out its pharmacological action over the management of acute and chronic pain and provide a base by further investigations., Significance: Antinociceptive effect of garlic and its OSCs has been extensively evaluated in preclinical models and clinical assays to treat different diseases, contributing to the modulation of inflammation as an essential factor in reducing pain. The current review emphasizes the potential therapeutic effect of garlic and its derivatives in treatment of pain and related mechanisms of action. Moreover, it provides information about the potential clinical use in patients with painful conditions., (© 2022 European Pain Federation - EFIC®.)

Tuberculosis (TB) is one of the ten leading causes of death worldwide. Patients with TB have been observed to suffer from depression and anxiety linked to social variables. Previous experiments found that the substantial pulmonary inflammation associated with TB causes neuroinflammation, neuronal death, and behavioral impairments in the absence of brain infection. Curcumin (CUR) is a natural product with antioxidant, anti-inflammatory and antibacterial activities. In this work, we evaluated the CUR effect on the growth control of mycobacteria in the lungs and the anti-inflammatory effect in the brain using a model of progressive pulmonary TB in BALB/c mice infected with drug-sensitive mycobacteria (strain H37Rv). The results have shown that CUR decreased lung bacilli load and pneumonia of infected animals. Finally, CUR significantly decreased neuroinflammation (expression of TNFα, IFNγ and IL12) and slightly increased the levels of nuclear factor erythroid 2-related to factor 2 (Nrf2) and the brain-derived neurotrophic factor (BDNF) levels, improving behavioral status. These results suggest that CUR has a bactericidal effect and can control pulmonary mycobacterial infection and reduce neuroinflammation. It seems that CUR has a promising potential as adjuvant therapy in TB treatment.

Garlic ( Allium sativum ) has been used in alternative medicine to treat several diseases, such as cardiovascular and neurodegenerative diseases, cancer, and hepatic diseases. Several publications have highlighted other features of garlic, including its antibacterial, antioxidative, antihypertensive, and antithrombotic properties. The properties of garlic result from the combination of natural compounds that act synergistically and cause different effects. Some garlic-derived compounds have been studied for the treatment of several types of cancer; however, reports on the effects of garlic on neuroblastoma are scarce. Neuroblastoma is a prevalent childhood tumor for which the search for therapeutic alternatives to improve treatment without affecting the patients' quality of life continues. Garlic-derived compounds hold potential for the treatment of this type of cancer. A review of articles published to date on some garlic compounds and their effect on neuroblastoma was undertaken to comprehend the possible therapeutic role of these compounds. This review aimed to analyze the impact of some garlic compounds on cells derived from neuroblastoma.

Tuberculosis (TB) is a chronic infectious disease in which prolonged, non-resolutive inflammation of the lung may lead to metabolic and neuroendocrine dysfunction. Previous studies have reported that individuals coursing pulmonary TB experience cognitive or behavioural changes; however, the pathogenic substrate of such manifestations have remained unknown. Here, using a mouse model of progressive pulmonary TB, we report that, even in the absence of brain infection, TB is associated with marked increased synthesis of both inflammatory and anti-inflammatory cytokines in discrete brain areas such as the hypothalamus, the hippocampal formation and cerebellum accompanied by substantial changes in the synthesis of neurotransmitters. Moreover, histopathological findings of neurodegeneration and neuronal death were found as infection progressed with activation of p38, JNK and reduction in the BDNF levels. Finally, we perform behavioural analysis in infected mice throughout the infection, and our data show that the cytokine and neurochemical changes were associated with a marked onset of cognitive impairment as well as depressive- and anxiety-like behaviour. Altogether, our results suggest that besides pulmonary damage, TB is accompanied by an extensive neuroinflammatory and neurodegenerative state which explains some of the behavioural abnormalities found in TB patients., Competing Interests: The authors of this manuscript declare that there are no actual or potential conflicts of interest. The authors affirm that there are no financial, personal or other relationships with other people or organisations that have inappropriately influenced or biased their research.

Depression is a psychiatric disorder, and oxidative stress is a significant mechanism of damage in this mood disorder. It is characterized by an enhancement of oxidative stress markers and low concentrations of endogenous antioxidants, or antioxidants enzymes. This suggests that antioxidants could have an antidepressant effect. S-allyl cysteine (SAC) is a compound with antioxidant action or free radical scavenger capacity. The purpose of the current research was to evaluate the antidepressant-like effect as well as the antioxidant role of SAC on a preclinical test, using the Porsolt forced swim test (FST). SAC (30, 70, 120, or 250 mg/kg, ip) was administered to male BALB/c mice daily for 17 days, followed by the FST at day 18. Oxidative stress markers (reactive oxygen species, superoxide production, lipid peroxidation, and antioxidant enzymes activities) were analyzed in the midbrain, prefrontal cortex, and hippocampus. SAC (120 mg/kg) attenuated the immobility scores (44%) in the FST, and protection was unrelated to changes in locomotor activity. This antidepressant-like effect was related to decreased oxidative stress, as indicated by lipid peroxidation and manganese-superoxide dismutase (Mn-SOD) activity in the hippocampus. SAC exerts an antidepressant-like effect that correlated, in part, with preventing oxidative damage in hippocampus.

Stroke is a public health problem due to its high mortality and disability rates; despite these, the pharmacological treatments are limited. Oxidative stress plays an important role in cerebral damage in stroke and the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) confers protection against oxidative stress. Different compounds, such as diallyl trisulfide (DATS), have the ability to activate Nrf2. DATS protects against the damage induced in oxygen-glucose deprivation in neuronal cells; however, in in vivo models of cerebral ischemia, DATS has not been evaluated. Male Wistar rats were subjected to 1 h of ischemia and seven days of reperfusion and the protective effect of DATS was evaluated. DATS administration (IR + DATS) decreased the infarct area and brain damage in the striatum and cortex; improved neurological function; decreased malondialdehyde and metalloproteinase-9 levels; increased Nrf2 activation in the cortex and the expression of superoxide dismutase 1 (SOD1) in the nucleus, SOD2 and glutathione S-transferase (GST) in the striatum and cortex; and increased the activity of catalase (CAT) in the striatum and glutathione peroxidase (GPx) in the cortex. Our results demonstrate the protective effect of DATS in an in vivo model of cerebral ischemia that involves Nrf2 activation.

In the present study we investigated the participation of brain-derived neurotropic factor (BDNF) on the activation of the mitogen activated protein kinase (MAPK) protein extracellular signal-regulated kinase-1/2 (ERK1/2) as a mechanism of curcumin (CUR) to provide an antioxidant defense system mediated by the nuclear factor erythroid 2-related factor 2 (Nrf2) in the neurotoxic model induced by quinolinic acid (QUIN). Wistar rats received CUR (400 mg/kg, intragastrically) for 6 days after intrastriatal injection with QUIN (240 nmol). CUR improved the motor deficit and morphological alterations induced by QUIN and restored BDNF, ERK1/2, and Nrf2 levels. CUR treatment avoided the decrease in the protein levels of glutathione peroxidase (GPx), glutathione reductase (GR), γ-glutamylcysteine ligase (γ-GCL), and glutathione (GSH) levels. Only, the QUIN-induced decrease in the GR activity was prevented by CUR treatment. Finally, QUIN increased superoxide dismutase 2 (SOD2) and catalase (CAT) levels, and the γGCL and CAT activities; however, this increase was major in the QUIN+CUR group for γ-GCL, CAT, and SOD activities. These data suggest that the therapeutic effect of CUR could involve BDNF action on the activation of ERK1/2 to induce increased levels of protein and enzyme activity of antioxidant proteins regulated by Nrf2 and GSH levels.

Quinolinic acid (QUIN) is an excitotoxic and pro-oxidant molecule used in the study of neurodegenerative disorders because it reproduces certain biochemical characteristics present in these diseases. The use of antioxidant molecules in the QUIN model reduces cellular damage through the nuclear factor erythroid 2-related to factor 2 (Nrf2) pathway. The Nrf2 transcription factor is considered the master regulator of antioxidant genes expression, and its activation occurs by an increase in the reactive oxygen species (ROS) levels or in the presence of electrophilic compounds. However, Nrf2 activation also occurs in an oxidative stress-independent process caused by the disruption of the Keap1-Nrf2 complex by the direct interaction of Keap1 with certain proteins, such as DPP3 and p62. The aim of this study was to evaluate the effect of QUIN on Nrf2 activation over short periods of time. QUIN administration increased Nrf2 activation at 30 min in the striatum without increasing ROS production or modifying the redox cellular state. Moreover, QUIN increased Keap1 and Nrf2 nuclear levels and increased the protein-protein interaction between Keap1 and DPP3 and Keap1 and p62 30 min after QUIN administration. Finally, we found that Nrf2 activation primarily occurs in striatal neurons. Our results show that QUIN administration in vivo stimulates Nrf2 expression and activation in the absence of oxidative stress primarily in neurons and increases the interaction of p62 and DPP3 with Keap1, which could participate in Nrf2 activation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Nuclear Factor Erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates the expression of genes involved in the metabolism, immune response, cellular proliferation, and other processes; however, the attention has been focused on the study of its ability to induce the expression of proteins involved in the antioxidant defense. Nrf2 is mainly regulated by Kelch-like ECH-associated protein 1 (Keap1), an adapter substrate of Cullin 3 (Cul3) ubiquitin E3 ligase complex. Keap1 represses Nrf2 activity in the cytoplasm by its sequestering, ubiquitination and proteosomal degradation. Nrf2 activation, through the canonical mechanism, is carried out by electrophilic compounds and oxidative stress where some cysteine residues in Keap1 are oxidized, resulting in a decrease in Nrf2 ubiquitination and an increase in its nuclear translocation and activation. In the nucleus, Nrf2 induces a variety of genes involved in the antioxidant defense. Recently a new mechanism of Nrf2 activation has been described, called the non-canonical pathway, where proteins such as p62, p21, dipeptidyl peptidase III (DPP3), wilms tumor gene on X chromosome (WTX) and others are able to disrupt the Nrf2-Keap1 complex, by direct interaction with Keap1 decreasing Nrf2 ubiquitination and increasing its nuclear translocation and activation. In this review, the regulatory mechanisms involved in both canonical and non-canonical Nrf2 activation are discussed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Oxidative stress secondary to excitotoxicity is a common factor in the physiopathology of a variety of neurological disorders. In response to oxidative stress, several signaling pathways, such as MAPK, are activated or inactivated. Mitogen-activated protein kinase (MAPK) family activation must be finely regulated in time and intensity, as this pathway may either preserve cell survival or promote cell death. In the present study, the activation of MAPK in the excitotoxic injury induced by quinolinic acid (QUIN) was examined in vivo, at short and long times. We used different doses (30, 60, 120 and 240 nmol) of QUIN injected intrastriatally in the right rat striatum and the effect of this treatment on motor deficits, cellular damage, MAPK activation and BDNF/TrkB axis, were evaluated at 2 h and 7 days post-lesion. Higher doses of QUIN (120 and 240 nmol) induced rat motor deficits and caused morphological changes in neurons around the lesion core. QUIN decreased the activation of ERK1/2 in a dose-dependent manner at 7 days post-injection, and induced a sustained increase of c-Jun NH2-terminal kinase (JNK) activation from 2 h to 7 days post-injury. JNK activation was dependent on the QUIN-induced NMDAr activation (only 120 nmol). No significant difference in p38 activation with QUIN was observed. QUIN (120 and 240 nmol) decreased BDNF/TrkB levels at 7 days post-injury. JNK inhibition (by an intracerebroventricular injection of SP600125) prevented the QUIN-induced reduction in BDNF and TrkB at 7 day post-injury, suggesting a role for the QUIN-induced JNK activation on the observed decrease in BDNF levels., (Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.)

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Oxidative stress plays an important role in neurodegenerative diseases and aging. The cellular defense mechanisms to deal with oxidative damage involve the activation of transcription factor related to NF-E2 (Nrf2), which enhances the transcription of antioxidant and phase II enzyme genes. S-allylcysteine (SAC) is an antioxidant with neuroprotective properties, and the main organosulfur compound in aged garlic extract. The ability of SAC to activate the Nrf2 factor has been previously reported in hepatic cells; however this effect has not been studied in normal brain. In order to determine if the chronic administration of SAC is able to activate Nrf2 factor and enhance antioxidant defense in the brain, male Wistar rats were administered with SAC (25, 50, 100 and 200 mg/kg-body weight each 24 h, i.g.) for 90 days. The activation of Nrf2, the levels of p65 and 8-hydroxy-2-deoxyguanosine (8-OHdG) as well as the activities of the enzymes glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) were evaluated in the hippocampus, striatum and frontal cortex. Results showed that SAC activated Nrf2 factor in the hippocampus (25-200 mg/kg) and striatum (100 mg/kg) and significantly decreased p65 levels in the frontal cortex (25-200 mg/kg). On the other hand, SAC increased GPx, GR, CAT and SOD activities mainly in the hippocampus and striatum, but it did not change GST activity. Finally, no changes were observed in 8-OHdG levels mediated by SAC in any brain region, but the hippocampus showed a major level of 8-OHdG compared with the striatum and frontal cortex. All these results suggest that in the hippocampus, the observed increase in the activity of antioxidant enzymes could be associated with the ability of SAC to activate Nrf2 factor; however, a different mechanism could be involved in the striatum and frontal cortex, since no changes were found in Nrf2 activation and p65 levels.

Apocynin (APO) is a well-known NADPH oxidase (NOX) inhibitor. However, several studies have reported its ability to increase glutathione (GSH) levels. Due to GSH is a major non-enzymatic antioxidant in brain, the aim of this study was to evaluate, in the striatum of control and quinolinic acid (QUIN) injected rats, the effect of APO administration on: (1) GSH levels, (2) activity of some enzymes involved in the GSH metabolism, and (3) nuclear factor erythroid-2-related factor 2 (Nrf2) mRNA levels. Animals received QUIN 240nmol in right striatum and APO (5mg/kg, i.p.), 30min before and 60min after intrastriatal injection. APO treatment prevented the QUIN-induced histological damage to the striatum. In control rats, APO treatment increased GSH and Nrf2 mRNA levels and the activities of gamma-glutamylcysteine ligase (γ-GCL), glutathione-S-transferase (GST) and glutathione peroxidase (GPx). On the other hand, APO treatment prevented the QUIN-induced decrease in GSH and Nrf2 levels, and in γ-GCL and GPx activities. These data indicate that APO is able to increase GSH levels and the activity of proteins involved in its metabolism, which could be associated with its ability to increase the Nrf2 mRNA levels., (Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.)

Background: Aged garlic extract (AGE) and its main constituent S-allylcysteine (SAC) are natural antioxidants with protective effects against cerebral ischemia or cancer, events that involve hypoxia stress. Cobalt chloride (CoCl2) has been used to mimic hypoxic conditions through the stabilization of the α subunit of hypoxia inducible factor (HIF-1α) and up-regulation of HIF-1α-dependent genes as well as activation of hypoxic conditions such as reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and apoptosis. The present study was designed to assess the effect of AGE and SAC on the CoCl2-chemical hypoxia model in PC12 cells., Results: We found that CoCl2 induced the stabilization of HIF-1α and its nuclear localization. CoCl2 produced ROS and apoptotic cell death that depended on hypoxia extent. The treatment with AGE and SAC decreased ROS and protected against CoCl2-induced apoptotic cell death which depended on the CoCl2 concentration and incubation time. SAC or AGE decreased the number of cells in the early and late stages of apoptosis. Interestingly, this protective effect was associated with attenuation in HIF-1α stabilization, activity not previously reported for AGE and SAC., Conclusions: Obtained results show that AGE and SAC decreased apoptotic CoCl2-induced cell death. This protection occurs by affecting the activity of HIF-1α and supports the use of these natural compounds as a therapeutic alternative for hypoxic conditions.

Aims: This simple study was designed to investigate whether acute restraint stress can generate changes in behavioral tests and hippocampal endpoints of oxidative stress in rats, and if the antioxidant S-allyl cysteine (SAC) can prevent these alterations., Materials and Methods: We evaluated motor activity, forced swimming and anxiety behavior, as well as the hippocampal levels of lipid peroxidation and the activities of glutathione-related enzymes in animals submitted to mild immobilization. The effect of SAC (100 mg/kg, i.p.), given to rats every day 30 min before starting the immobilization session, was also investigated. Immobilization (restraint) stress was induced for a period of 6 h per day for five consecutive days., Key Findings: Our results indicate that, under the tested conditions, acute restraint stimulates compensatory behavioral tasks (motor activity, anxiety and forced swimming) to counteract the stressing conditions prevailing, and selectively increased the levels of lipid peroxidation and the enzyme activities of glutathione-S-transferase (GST) and glutathione peroxidase (GPx) in the hippocampus also as adaptive responses. SAC exhibited preventive effects in the stressed group as it improved behavior, reduced lipid peroxidation and prevented the increase of GST and GPx activities, suggesting that this antioxidant blunted primary pro-oxidative stimuli induced by restraint stress., Significance: Findings of this work also confirm that the use of antioxidants such as SAC can provide effective protection against the acute oxidative damage associated with anxiety produced by stressing conditions., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Parkinson's disease has been associated with the selective loss of neurons in the substantia nigra pars compacta. Increasing evidence suggests that oxidative stress plays a major role. The resulting increase in reactive oxygen species triggers a sequence of events that leads to cell damage, activation of microglia cells and neuroinflammatory responses. Our objective was to study whether chronic exposure to low doses of ozone, which produces oxidative stress itself, induces progressive cell death in conjunction with glial alterations in the substantia nigra. Animals were exposed to an ozone-free air stream (control) or to low doses of ozone for 7, 15, 30, 60, or 90 days. Each group underwent (1) spectrophotometric analysis for protein oxidation; (2) western blot testing for microglia reactivity and nuclear factor kappa B expression levels; and (3) immunohistochemistry for cytochrome c, GFAP, Iba-1, NFkB, and COX-2. Our results indicate that ozone induces an increase in protein oxidation levels, changes in activated astrocytes and microglia, and cell death. NFkB and cytochrome c showed an increase until 30 days of exposure, while cyclooxygenase 2 in the substantia nigra increased from 7 days up to 90 days of repetitive ozone exposure. These results suggest that oxidative stress caused by ozone exposure induces changes in inflammatory responses and progressive cell death in the substantia nigra in rats, which could also be occurring in Parkinson's disease.

The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS) and the left ventricular end diastolic pressure (LVEDP). Twenty-five patients with essential hypertension and 25 controls paired by age and gender were studied. All of the participants were subjected to echocardiography and biochemical determination of oxidative stress markers. The hypertensive patients, compared with control subjects, had significantly (p < 0.05) higher levels of oxidized proteins (5.03 ± 1.05 versus 4.06 ± 0.63 nmol/mg), lower levels of extracellular superoxide dismutase (EC-SOD) activity (0.045 ± 0.02 versus 0.082 ± 0.02 U/mg), higher LVEDP (16.2 ± 4.5 versus 11.3 ± 1.6 mm Hg), and lower GLS (-12% versus -16%). Both groups had preserved ejection fraction and the results showed a positive correlation of oxidized proteins with GLS (r = 0.386, p = 0.006) and LVEDP (r = 0.389, p = 0.005); we also found a negative correlation of EC-SOD activity with GLS (r = -0.404, p = 0.004) and LVEDP (r = -0.347, p = 0.014).

Objectives: Cisplatin (CP) is an antineoplastic agent that induces nephrotoxicity and oxidative stress. S-allylcysteine (SAC) is a garlic-derived antioxidant. This study aims to explore whether SAC protects against CP-induced nephrotoxicity in rats., Methods: In the first stage, the SAC protective dose was determined by measuring renal damage and the oxidative stress markers malondialdehyde, oxidized proteins and glutathione in rats injected with CP. In the second stage, the effect of a single dose of SAC on the expression of nuclear factor-erythroid 2-related factor-2 (Nrf2), protein kinase C beta 2 (PKCβ2) and nicotinamide adenine dinucleotide phosphate oxidase subunits (p47(phox) and gp91(phox) ) was studied. In addition, the effect of SAC on oxidative stress markers and on the activity of catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) in isolated proximal and distal tubules were evaluated., Key Findings: SAC (25 mg/kg) prevented the CP-induced renal damage and attenuated CP-induced decrease in Nrf2 levels and increase in PKCβ2, p47(phox) and gp91(phox) expression in renal cortex and oxidative stress and decrease in the activity of CAT, GPx and GR in proximal and distal tubules., Conclusions: These data suggest that SAC provides renoprotection by attenuating CP-induced oxidative stress and decrease in the activity of CAT, GPx and GR., (© 2014 Royal Pharmaceutical Society.)

Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities., (Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.)

The neuroprotective properties of S-allyl cysteine (SAC) have been demonstrated in different neurotoxic paradigms, and it may be partially attributable to its antioxidant and anti-inflammatory profile. Recently, SAC has also been shown to induce neuroprotection in the rat striatum in a toxic model induced by 6-hydroxydopamine in rats through a concerted antioxidant response involving Nrf2 transcription factor nuclear transactivation and Phase 2 enzymes' upregulation. In this work, we investigated whether the SAC-induced in vivo striatal and nigral neuroprotection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridinium (MPTP) toxicity recruits Nrf2 transactivation in C57BL/6J mice. SAC (120 mg/kg, i.p. × 5 days) partially ameliorated the MPTP (30 mg/kg, i.p. × 5 days)-induced striatal and nigral dopamine and tyrosine hydroxylase depletion, attenuated the loss of Mn-SOD and HO-1 activities, and preserved the protein content of these enzymes. While no significant changes were detected for the striatal Nrf2 nuclear protein levels, the nigral Nrf2 nuclear content was decreased by MPTP and stimulated by SAC. Our findings suggest that SAC can exert neuroprotection since the origin of the dopaminergic lesion-at the substantia nigra (SN)-not only by means of direct antioxidant actions, but also through Nrf2 nuclear transactivation and Phase 2 enzymes upregulation.

Characterization of auto-destructive mechanisms, leading to cell death after spinal cord injury (SCI) is important to prevent further damage to tissue. Heme oxygenase (HO) catalyzes the oxidation of heme to biliverdin and carbon monoxide (CO), as a response to cell damage. Products of HO action have biological effects, as antioxidant biliverdin. We evaluated the changes of HO activity after injury, and the effect of pharmacological treatments with hemin (an inducer) and (Sn)-protoporphyrin (an inhibitor, Sn-PPIX) of HO, upon motor recovery after SCI. Female Wistar rats were submitted to SCI by trauma and sacrificed at several times (2, 4, 8, 12 and 24h) after injury to evaluate HO activity. Additional groups of rats were treated with either hemin or Sn-PPIX, to evaluate motor recovery, spared spinal cord tissue and HO activity. Results showed that HO control activity was increased by effect of SCI, at all times evaluated, as compared to sham group values. Twenty-four hours after injury, HO activity was increased 7.2-fold by hemin treatment, as compared to SCI plus vehicle group values. In addition, animals treated with hemin 2 and 8h after SCI, showed a better motor recovery and higher spared cord tissue, as compared to control group values. Our findings indicate that activation of HO is a beneficial mechanism when attained during the acute phase after SCI., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Quinolinic acid (QA)-induced overactivation of N-methyl-d-aspartate receptors yields excitotoxicity, oxidative stress and mitochondrial dysfunction, which altogether contribute to trigger a wide variety of toxic pathways with biochemical, behavioral and neuropathological alterations similar to those observed in Huntington's disease. Noteworthy, in the brains of these patients, increased expression of heme oxygenase-1 (HO-1) levels can be found. It has been proposed that this enzyme can exert a dual role, as it can be either protective or deleterious to the CNS. While some evidence indicates that its overexpression affords cellular anti-oxidant protection due to decreased concentrations of its pro-oxidative substrate heme group, and increased bilirubin levels, other reports established that high HO-1 expression and activity may result in a pro-oxidizing atmosphere due to a release of Fe(2+). In this work, we examined the temporal evolution of oxidative damage to proteins, HO-1 expression, immunoreactivity, total activity, and cell death after 1, 3, 5 and 7 days of an intrastriatal QA infusion (240 nmol/μl). QA was found to induce cellular degeneration, increasing carbonylated proteins and generating a transitory response in HO-1 mRNA, protein content, and immunoreactivity and activity in nerve cells. In order to study the role of HO-1 in the QA-induced cellular death, the tin protoporphyrin IX (SnPP), a well-known HO inhibitor, was administered to rats (30 μmol/kg, i.p.). The administration of SnPP to animals treated with QA inhibited the HO activation, and exacerbated the striatal cell damage induced by QA. Our findings reveal a potential modulatory role of HO-1 in the toxic paradigm evoked by QA in rats. This evidence provides a valuable tool for further approaches on HO-1 regulation in neurotoxic paradigms., (Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.)

The exposure to hexavalent chromium is often known to cause acute renal failure. It has been found that nonenzymatic antioxidants and the induction of heme oxygenase 1 have protective effects against nephrotoxicity induced by potassium dichromate in vivo. In this work, the effect of stannous chloride, an inducer of heme oxygenase 1, on potassium dichromate-induced toxicity in proximal tubular epithelial cells was studied. Hexavalent chromium levels, peroxynitrite content, reduced thiol content, heme oxygenase activity, reactive oxygen species production, and stannous chloride scavenging capacity were measured. It was found that stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced cell death. The decrease in extracellular and intracellular hexavalent chromium concentration, the induction of heme oxygenase 1, and the ability to scavenge reactive oxygen species and peroxynitrite are involved in the mechanism by which stannous chloride protects proximal tubular epithelial cells from potassium dichromate-induced toxicity.

Kynurenine pathway is gaining attention due to the many metabolic processes in which it has been involved. The tryptophan conversion into several other metabolites through this pathway provides neuronal and redox modulators useful for maintenance of major functions in the brain. However, when physiopathological conditions prevail - i.e. oxidative stress, excitotoxicity, and inflammation - preferential formation and accumulation of toxic metabolites could trigger factors for degeneration in neurological disorders. 3-Hydroxykynurenine has been largely described as one of these toxic metabolites capable of inducing oxidative damage and cell death; consequently, this metabolite has been hypothesized to play a pivotal role in different neurological and psychiatric disorders. Supporting evidence has shown altered 3-hydroxykynurenine levels in samples of patients from several disorders. In contrast, some experimental studies have provided evidence of antioxidant and scavenging properties inherent to this molecule. In this review, we explored most of literature favoring one or the other concept, in order to provide an accurate vision on the real participation of this tryptophan metabolite in both experimental paradigms and human brain pathologies. Through this collected evidence, we provide an integrative hypothesis on how 3-hydroxykynurenine is exerting its dual actions in the central nervous system and what will be the course of investigations in this field for the next years., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Pharmacological activation at the basal ganglia of the transcription factor Nrf2, guardian of redox homeostasis, holds a strong promise for the slow progression of Parkinson's disease (PD). However, a potent Nrf2 activator in the brain still must be found. In this study, we have investigated the potential use of the antioxidant compound S-allyl cysteine (SAC) in the activation of Nrf2 in 6-hydoxydopamine (6-OHDA)-intoxicated rats. In the rat striatum, SAC by itself promoted the Nrf2 dissociation of Keap-1, its nuclear translocation, the subsequent association with small MafK protein, and further binding of the Nrf2/MafK complex to ARE sequence, as well as the up-regulation of Nrf2-dependent genes encoding the antioxidant enzymes HO-1, NQO-1, GR, and SOD-1. In vivo and in vitro experiments to identify signaling pathways activated by SAC pointed to Akt as the most likely kinase participating in Nrf2 activation by SAC. In PC12 cells, SAC stimulated the activation of Akt and ERK1/2 and inhibited JNK1/2/3 activation. In the rat striatum, the SAC-induced activation of Nrf2 is likely to contribute to inhibit the toxic effects of 6-OHDA evidenced by phase 2 antioxidant enzymes up-regulation, glutathione recovery, and attenuation of reactive oxygen species (ROS), nitric oxide (NO), and lipid peroxides formation. These early protective effects correlated with the long-term preservation of the cellular redox status, the striatal dopamine (DA) and tyrosine hydroxylase (TH) levels, and the improvement of motor skills. Therefore, this study indicates that, in addition to direct scavenging actions, the activation of Nrf2 by SAC might confer neuroprotective responses through the modulation of kinase signaling pathways in rodent models of PD, and suggests that this antioxidant molecule may have a therapeutic value in this human pathology., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: In a previous report, we have characterized the antiperoxidative properties of alpha-mangostin in different toxic models tested in nerve tissue preparations., Objectives: Here, the modulatory effects of this xanthone on the glutathione system (reduced glutathione (GSH) levels, glutathione peroxidase (GPx), and glutathione S-transferase (GST) activities) were tested in synaptosomal P2 fractions isolated from rat brains in order to provide further information on key mechanisms exerted by this antioxidant in the nervous system., Methods: Synaptosomes were exposed to increasing concentrations of the xanthone, and also challenged to the toxic actions of a free radical generator, ferrous sulfate (FeSO(4)). For comparative purposes, the mitochondrial toxin 3-nitropropionic acid (3-NP) was also explored., Results: Alpha-mangostin significantly decreased the levels of GSH, and increased GPx activity., Discussion: This finding was interpreted as a modulatory action of the GSH system in preparation to exert antioxidant responses. Although FeSO(4) exhibited similar effects, these were interpreted as a compensatory response to the toxic actions of the pro-oxidant. We came to this conclusion based on our previous report where alpha-mangostin produced antiperoxidative effects and FeSO(4) produced oxidative damage to lipids. GST activity remained unaffected by both the antioxidant and the pro-oxidant. Our results suggest that alpha-mangostin is able to modulate GPx activity as a potential antioxidant strategy, thereby transiently consuming GSH levels.

Selenium (Se) is a crucial element exerting antioxidant and neuroprotective effects in different toxic models. It has been suggested that Se acts through selenoproteins, of which thioredoxin reductase (TrxR) is relevant for reduction of harmful hydroperoxides and maintenance of thioredoxin (Trx) redox activity. Of note, the Trx/TrxR system remains poorly studied in toxic models of degenerative disorders. Despite previous reports of our group have demonstrated a protective role of Se in the excitotoxic/pro-oxidant model induced by quinolinic acid (QUIN) in the rat striatum (Santamaría et al., 2003, 2005), the precise mechanism(s) by which Se is inducing protection remains unclear. In this work, we characterized the time course of protective events elicited by Se as pretreatment (Na(2)SO(3), 0.625 mg/kg/day, i.p., administered for 5 consecutive days) in the toxic pattern produced by a single infusion of QUIN (240 nmol/μl) in the rat striatum, to further explore whether TrxR is involved in the Se-induced protection and how is regulated. Se attenuated the QUIN-induced early reactive oxygen species formation, lipid peroxidation, oxidative damage to DNA, loss of mitochondrial reductive capacity and morphological alterations in the striatum. Our results also revealed a novel pattern in which QUIN transiently stimulated an early TrxR cellular localization/distribution (at 30 min and 2 h post-lesion, evidenced by immunohistochemistry), to further stimulate a delayed protein activation (at 24 h) in a manner likely representing a compensatory response to the oxidative damage in course. In turn, Se induced an early stimulation of TrxR activity and expression in a time course that "matches" with the reduction of the QUIN-induced oxidative damage, suggesting that the Trx/TrxR system contributes to the resistance of nerve tissue to QUIN toxicity., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Aged garlic extract (AGE) is an odorless garlic preparation containing S-allylcysteine (SAC) as its most abundant compound. A large number of studies have demonstrated the antioxidant activity of AGE and SAC in both in vivo--in diverse experimental animal models associated to oxidative stress--and in vitro conditions--using several methods to scavenge reactive oxygen species or to induce oxidative damage. Derived from these experiments, the protective effects of AGE and SAC have been associated with the prevention or amelioration of oxidative stress. In this work, we reviewed different antioxidant mechanisms (scavenging of free radicals and prooxidant species, induction of antioxidant enzymes, activation of Nrf2 factor, inhibition of prooxidant enzymes, and chelating effects) involved in the protective actions of AGE and SAC, thereby emphasizing their potential use as therapeutic agents. In addition, we highlight the ability of SAC to activate Nrf2 factor--a master regulator of the cellular redox state. Here, we include original data showing the ability of SAC to activate Nrf2 factor in cerebral cortex. Therefore, we conclude that the therapeutic properties of these molecules comprise cellular and molecular mechanisms at different levels.

S-Allylcysteine (SAC) is the most abundant compound in aged garlic extracts, and its antioxidant properties have been demonstrated. It is known that SAC is able to scavenge different reactive species including hydroxyl radical (•OH), although its potential ability to scavenge peroxyl radical (ROO•) has not been explored. In this work the ability of SAC to scavenge ROO• was evaluated, as well as the role of the allyl group (-S-CH(2)-CH═CH(2)) in its free radical scavenging activity. Two derived compounds of SAC were prepared: S-benzylcysteine (SBC) and S-propylcysteine (SPC). Their abilities to scavenge •OH and ROO• were measured. A computational analysis was performed to elucidate the mechanism by which these compounds scavenge •OH and ROO•. SAC was able to scavenge •OH and ROO•, in a concentration-dependent way. Such activity was significantly ameliorated when the allyl group was replaced by benzyl or propyl groups. It was shown for the first time that SAC is able to scavenge ROO•.

Different garlic products reduce the cerebral ischemic damage due to their antioxidant properties. In this work, we investigated the effect of aged garlic extract (AGE) on cyclooxygenase-2 (COX-2) protein levels and activity, and its role as a possible mechanism of neuroprotection in a cerebral ischemia model. Animals were subjected to 1 h of ischemia plus 24 h of reperfusion. AGE (1.2 ml/kg weight, i.p.) was administered at onset of reperfusion. To evaluate the damage induced by cerebral ischemia, the neurological deficit, the infarct area, and the histological alterations were measured. As an oxidative stress marker to deoxyribonucleic acid, 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were determined. Finally, as inflammatory markers, TNFα levels and COX-2 protein levels and activity were measured. AGE treatment diminished the neurological alterations (61.6%), the infarct area (54.8%) and the histological damage (37.7%) induced by cerebral ischemia. AGE administration attenuated the increase in 8-OHdG levels (77.8%), in TNFα levels (76.6%), and in COX-2 protein levels (73.6%) and activity (30.7%) induced after 1 h of ischemia plus 24 h of reperfusion. These data suggest that the neuroprotective effect of AGE is associated not only to its antioxidant properties, but also with its capacity to diminish the increase in TNFα levels and COX-2 protein expression and activity. AGE may have the potential to attenuate the cerebral ischemia-induced inflammation.

In this work, the effect of a single dose of diazepam was tested on different markers of oxidative damage in the striatum of rats in an acute model of immobilization (restraint) stress. In addition, the locomotor activity was measured at the end of the restraint period. Immobilization was induced to animals for 24 hr, and then, lipid peroxidation, superoxide dismutase activity and content, and mitochondrial function were all estimated in striatal tissue samples. Corticosterone levels were measured in serum. Diazepam was given to rats as a pre-treatment (1 mg/kg, i.p.) 20 min. before the initiation of stress. Our results indicate that acute stress produced enhanced striatal levels of lipid peroxidation (73% above the control), decreased superoxide dismutase activity (54% below the control), reduced levels of mitochondrial function (35% below the control) and increased corticosterone serum levels (86% above the control). Pre-treatment of stressed rats with diazepam decreased the striatal lipid peroxidation levels (68% below the stress group) and improved mitochondrial function (18% above the stress group), but only mild preservation of superoxide dismutase activity was detected (17% above the stress group). In regard to the motor assessment, only the stereotyped activity was increased in the stress group with respect to control (46% above the control), and this effect was prevented by diazepam administration (30% below the stress group). The preventive actions of diazepam in this acute model of stress suggest that drugs exhibiting anxiolytic and antioxidant properties might be useful for the design of therapies against early acute phases of physic stress., (© 2011 The Authors. Basic & Clinical Pharmacology & Toxicology © 2011 Nordic Pharmacological Society.)

Kynurenic acid (KYNA) is an endogenous metabolite of the kynurenine pathway for tryptophan degradation and an antagonist of both N-methyl-D-aspartate (NMDA) and alpha-7 nicotinic acetylcholine (α7nACh) receptors. KYNA has also been shown to scavenge hydroxyl radicals (OH) under controlled conditions of free radical production. In this work we evaluated the ability of KYNA to scavenge superoxide anion (O(2)(-)) and peroxynitrite (ONOO(-)). The scavenging ability of KYNA (expressed as IC(50) values) was as follows: OH=O(2)(-)>ONOO(-). In parallel, the antiperoxidative and scavenging capacities of KYNA (0-150 μM) were tested in cerebellum and forebrain homogenates exposed to 5 μM FeSO(4) and 2.5 mM 3-nitropropionic acid (3-NPA). Both FeSO(4) and 3-NPA increased lipid peroxidation (LP) and ROS formation in a significant manner in these preparations, whereas KYNA significantly reduced these markers. Reactive oxygen species (ROS) formation were determined in the presence of FeSO(4) and/or KYNA (0-100 μM), both at intra and extracellular levels. An increase in ROS formation was induced by FeSO(4) in forebrain and cerebellum in a time-dependent manner, and KYNA reduced this effect in a concentration-dependent manner. To further know whether the effect of KYNA on oxidative stress is independent of NMDA and nicotinic receptors, we also tested KYNA (0-100 μM) in a biological preparation free of these receptors - defolliculated Xenopus laevis oocytes - incubated with FeSO(4) for 1 h. A 3-fold increase in LP and a 2-fold increase in ROS formation were seen after exposure to FeSO(4), whereas KYNA attenuated these effects in a concentration-dependent manner. In addition, the in vivo formation of OH evoked by an acute infusion of FeSO(4) (100 μM) in the rat striatum was estimated by microdialysis and challenged by a topic infusion of KYNA (1 μM). FeSO(4) increased the striatal OH production, while KYNA mitigated this effect. Altogether, these data strongly suggest that KYNA, in addition to be a well-known antagonist acting on nicotinic and NMDA receptors, can be considered as a potential endogenous antioxidant., (Copyright © 2011 Elsevier Inc. All rights reserved.)

This work focuses on the effect of acute stress on different markers of oxidative stress and mitochondrial dysfunction in the rat striatum. In addition, the effect of a single dose of l-carnitine (l-CAR, 300 mg/kg, i.p.) was evaluated in these animals. Immobilization (restraint) stress was induced to rats for 24 hr. The levels of lipid peroxidation (LP) and mitochondrial function (MF), as well as the superoxide dismutase (SOD) activity and content and reduced glutathione (GSH) levels, were all measured in striatal samples of animals subjected to stress. Our results indicate that acute stress is able to increase the striatal LP and reduced the levels of MF, while significantly lowered the manganese superoxide dismutase (Mn-SOD) activity. No changes were observed in the total striatal content of SOD, nor in GSH levels, but serum corticosterone content was increased by stress. l-CAR exhibited partial protective effects on the immobilized group, reducing the striatal LP and recovering the striatal MF and Mn-SOD activity. Our results suggest that acute restraint stress brings an accurate model for early pro-oxidant responses that can be targeted by broad-spectrum antioxidants like l-CAR., (© 2011 The Authors. Basic & Clinical Pharmacology & Toxicology © 2011 Nordic Pharmacological Society.)

We have recently demonstrated that S-allylcysteine (SAC) induces protection on neurochemical, biochemical and behavioral markers of striatal damage in different neurotoxic animal models - including a murine model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridinium (MPTP) injection to mice - indicating that pro-oxidant reactions underlie neurotoxicity in these models (García et al. 2008). In this work we investigated whether SAC can protect the striatum of mice from the morphological alterations in the MPTP toxic model, and if this response is correlated with a reduction in pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) expressions, and further reduction in astrocyte activation (glial fibrillary acidic protein (GFAP) expression). The striatal tissue from MPTP injected animals (30 mg/kg, i.p., ×5 days) showed a significant degree of cell damage and enhanced immunoreactivities to GFAP, TNF-α and iNOS, as well as an enhanced number of apoptotic nuclei. Treatment of mice with SAC (120 mg/kg, i.p., ×5 days) in parallel to MPTP significantly reduced or prevented all these markers. Our results suggest that MPTP-induced morphological alterations recruit a pro-inflammatory component triggered by cytokine TNF-α release and nitric oxide formation, which is sensitive to the antioxidant properties of SAC. This antioxidant is an effective experimental tool to reduce the brain lesions associated with oxidative damage and inflammatory responses., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

Experimental evidence has shown that some garlic-derived products have a protective effect against ischemic brain injury. The present study was designed to investigate the effect of aged garlic extract (AGE), establish the therapeutic window, and determine its protective mechanism in a cerebral ischemia model. Animals were subjected to middle cerebral artery occlusion (MCAO) for 2h and treated with 1.2ml/kg body wt.(i.p.) of AGE 30min before, at the beginning of (0R), or 1h after reperfusion. The 0R treatment significantly reduced the size of the infarct area after 2h of reperfusion. Repeated doses subsequent to the 0R treatment (at 1, 2, or 3h after reperfusion) had no effect on the temporal window of protection. The protective 0R treatment with AGE prevented the increase in nitrotyrosine and the decrease in total superoxide dismutase, glutathione peroxidase, and extracellular superoxide dismutase activities induced by MCAO. These data indicate that AGE delays the effects of ischemia/reperfusion-induced neuronal injury. However, this treatment itself was not associated with a noticeable improvement in the neurological outcome, or with an effect on the inflammatory response. We conclude that the neuroprotective effect of AGE in the 0R treatment might be associated with control of the free-radical burst induced by reperfusion, preservation of antioxidant enzyme activity, and the delay of other pathophysiological processes., (Copyright 2009 Elsevier GmbH. All rights reserved.)

Intrastriatal injection of quinolinic acid (QUIN) to rodents reproduces some biochemical, morphological, and behavioral characteristics of Huntington's disease. NAD(P)H oxidase is an enzymatic complex that catalyzes superoxide anion (O(2).(-)) production from O(2) and NADPH. The present study evaluated the role of NAD(P)H oxidase in the striatal damage induced by QUIN (240 nmol/microl) in adult male Wistar rats by means of apocynin (APO; 5 mg/kg i.p.), a specific NAD(P)H oxidase inhibitor. Rats were given APO 30 min before and 1 hr after QUIN injection or only 30 min after QUIN injection. NAD(P)H oxidase activity was measured in striatal homogenates by O2(*)(-) production. QUIN infusion to rats significantly increased striatal NAD(P)H oxidase activity (2 hr postlesion), whereas APO treatments decreased the QUIN-induced enzyme activity (2 hr postlesion), lipid peroxidation (3 hr postlesion), circling behavior (6 days postlesion), and histological damage (7 days postlesion). The addition of NADH to striatal homogenates increased NAD(P)H oxidase activity in striata from QUIN-treated animals but not from sham rats. Interestingly, O2(*)(-) production in QUIN-lesioned striata was unaffected by the addition of substrates for intramitochondrial O2(*)(-) production, xanthine oxidase and nitric oxide synthase, suggesting that NAD(P)H oxidase may be the main source of O2(*)(-) in QUIN-treated rats. Moreover, the administration of MK-801 to rats as a pretreatment resulted in a complete prevention of the QUIN-induced NAD(P)H activation, suggesting that this toxic event is completely dependent on N-methyl-D-aspartate receptor overactivation. Our results also suggest that NAD(P)H oxidase is involved in the pathogenic events linked to excitotoxic/prooxidant conditions., (Copyright 2009 Wiley-Liss, Inc.)

The functional preservation of nerve endings since the early stages of toxicity in a given damaging insult-either acute or chronic-by means of antioxidant and neuroprotective agents is a primary need to design therapeutic strategies for neurodegenerative disorders, with particular emphasis on those diseases with excitotoxic and depleted energy metabolism components. S-allylcysteine (SAC), a well-known antioxidant agent, was tested as a post-treatment in different in vitro and in vivo neurotoxic models. Quinolinic acid (QUIN) was used as a typical excitotoxic/pro-oxidant inducer, 3-nitropropionic acid (3-NP) was employed as a mitochondrial function inhibitor, and their combination (QUIN + 3-NP) was also evaluated in in vitro studies. For in vitro purposes, increasing concentrations of SAC (10-100 microM) were added to isolated brain synaptosomes at different times (1, 3 and 6 h) after the incubation with toxins (100 microM QUIN, 1 mM 3-NP or the combination of QUIN (21 microM) + 3-NP (166 microM). Thirty minutes later, lipid peroxidation (LP) and mitochondrial dysfunction (MD) were evaluated. For in vivo studies, SAC (100 mg/kg, i.p.) was given to QUIN- or 3-NP-striatally lesioned rats for 7 consecutive days (starting 120 min post-lesion). LP and MD were evaluated 7 days post-lesion in isolated striatal synaptosomes. Circling behavior was also assessed. Our results describe a differential pattern of protection achieved by SAC, mostly expressed in the 3-NP toxic model, in which nerve ending protection was found within the first hours (1 and 3) after the toxic insult started, supporting the concept that the ongoing oxidative damage and energy depletion can be treated during the first stages of neurotoxic events.

Tert-butylhydroquinone (tBHQ) is a xenobiotic with reported antioxidant properties. tBHQ has been shown to induce nuclear translocation of the transcription factor NF-E2-related factor 2 (Nrf2) to further activate the antioxidant response element (ARE). In turn, the Nrf2/ARE pathway is responsible for the induction of phase 2 antioxidant enzymes that detoxify oxidant promoters from different toxic insults. In this work, the antioxidant and protective actions of tBHQ were explored for the first time on different biomarkers of the neurotoxic model produced by the excitotoxic and pro-oxidant molecule quinolinic acid (QUIN) in rat striatal slices. For comparison purposes, 3-nitropropionic acid was used as reference model. Our results show that tBHQ (25 μM) prevented the QUIN-induced lipid peroxidation and mitochondrial dysfunction. In addition, tBHQ enhanced glutathione-S-transferase activity, partially recovering its depletion induced by QUIN treatment. Our results also demonstrated that tBHQ was able to induce nuclear accumulation of Nrf2 and further antioxidant protection: while QUIN alone decreased the nuclear Nrf2, a treatment with tBHQ preserved the nuclear levels Nrf2 in the presence of QUIN. Therefore, the tBHQ-mediated Nrf2/ARE induction constitutes a signaling-mediated antioxidant strategy and therapeutic tool to be tested in different neurotoxic models., (Copyright © 2009 S. Karger AG, Basel.)

Experimental evidence on the protective properties of S-allylcysteine (SAC) was collected from three models exerting striatal toxicity. In the first model, SAC (120 mg kg(-1)x5) prevented lipoperoxidation (LP) and mitochondrial dysfunction (MD) in synaptosomal fractions from 1-methyl-4-phenyl-1,2,3,6-tetrahydropiridinium-treated mice (30 mg kg(-1)), but without complete restoration of dopamine levels. In the second model, SAC (300 mg kg(-1)x 3), prevented LP and MD in synaptosomes from rats infused with 6-hydroxydopamine (8 microg microl(-1)) into the substantia nigra pars compacta, but again, without total reversion of depleted dopamine levels. In the third model, SAC (100 mg kg(-1)x 1) prevented MD in synaptosomes from rats injected with 3-nitropropionic acid (10 mg kg(-1)), but in contrast to the other models, it failed to prevent LP. SAC also prevented the aberrant motor activity patterns evoked by the three toxins. Altogether, the results suggest that the antioxidant properties of SAC are responsible for partial or total preservation of neurochemical, biochemical and behavioural markers, indicating that pro-oxidant reactions underlie the neurotoxicity in these models.

The effect of the garlic-derived antioxidant S-allylcysteine (SAC) on renal injury and oxidative stress induced by ischemia and reperfusion (IR) was studied in this work. Rats were anesthetized and subjected to right nephrectomy; 15 min later ischemia was induced for a period of 40 min and then the rats were subjected to a reperfusion period of 6 h after which they were killed to obtain blood and the left kidney. SAC was given at a dose of 100 mg/kg 30 min before nephrectomy, 15 min before ischemia, immediately before reperfusion and 2 h after reperfusion. IR-induced renal injury was evident by the increase in blood urea nitrogen (BUN) and serum creatinine as well as by the renal structural damage which was assessed by histological analysis. IR-induced oxidative stress was evident by the increase in immunostaining with 4-hydroxy-2-nonenal (4-HNE). SAC treatment was able to ameliorate the increase in BUN and serum creatinine and to decrease the structural damage. This protective effect was associated with a decrease in the immunostaining for 4-HNE. It is concluded that the antioxidant properties of SAC are involved in its protective effect on renal ischemia and reperfusion injury., (Copyright (c) 2008 John Wiley & Sons, Ltd.)

Excessive calcium is responsible for triggering different potentially fatal metabolic pathways during neurodegeneration. In this study, we evaluated the role of calcium on the oxidative damage produced in an in vitro combined model of excitotoxicity/energy deficit produced by the co-administration of quinolinate and 3-nitropropionate to brain synaptosomal membranes. Synaptosomal fractions were incubated in the presence of subtoxic concentrations of these agents (21 and 166 microm, respectively). In order further to characterize possible toxic mechanisms involved in oxidative damage in this experimental paradigm, agents with different properties - dizocilpine, acetyl L-carnitine, iron porphyrinate and S-allylcysteine - were tested at increasing concentrations (10-1000 microm). Lipid peroxidation was assessed by the formation of thiobarbituric acid-reactive substances. For confirmatory purposes, additional fractions were incubated in parallel in the presence of the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM). Under physiological conditions of extracellular calcium availability, synaptomes exposed to both toxins displayed an increased lipoperoxidation (76% above controls), and this effect was partially attenuated by the tested agents as follows: dizocilpine = iron porphyrinate > acetyl L-carnitine > S-allylcysteine. When the incubation medium was deprived of calcium, the lipoperoxidative effect achieved in this experimental paradigm was still high (49% above the control), and the order of attenuation was: iron porphyrinate > S-allylcysteine > acetyl L-carnitine > dizocilpine. BAPTA-AM was effective in preventing the pro-oxidant action of both toxins, promoting even lower peroxidative levels than those quantified under basal conditions. Our results suggest that the lipid peroxidation induced in synaptosomal fractions by quinolinate plus 3-nitropropionate is largely dependent on the cytoplasmic concentrations of calcium.

Excitotoxicity and oxidative stress are mechanisms involved in the neuronal cell death induced by the intrastriatal injection of quinolinic acid (QUIN) as a model of Huntington's disease. Production of nitric oxide by nitric oxide synthase (NOS) has been proposed to participate in QUIN-induced neurotoxicity; however, the precise role of NOS in QUIN-induced toxicity still remains controversial. In order to provide further information on the role of NOS isoforms in QUIN toxicity, we performed real time RT-PCR and immunohistochemistry of inducible NOS (iNOS), endothelial NOS (eNOS) and neuronal NOS (nNOS) and determined Ca(2+)-dependent and Ca(2+)-independent NOS activity in a temporal course (3-48h), after an intrastriatal injection of QUIN to rats. NOS isoforms exhibited a transitory expression of mRNA and protein after QUIN infusion: eNOS increased between 3 and 24h, iNOS between 12 and 24h, while nNOS at 35 and 48h. Ca(2+)-independent activity (iNOS) did not show any change, while Ca(2+)-dependent activity (constitutive NOS: eNOS/nNOS) exhibited increased levels at 3h. Our results support the participation of Ca(2+)-dependent NOS isoforms during the toxic events produced at early times after QUIN injection.