Oxidative stress in children affected by epileptic encephalopathies

Diet-derived circulating antioxidants and risk of epilepsy: a Mendelian randomization study

Background

Previous studies suggest a link between diet-derived circulating antioxidants and epilepsy, but the causal relationship is unclear. This study aims to investigate the causal effect of these antioxidants on epilepsy.

Methods

To assess the causal link between dietary antioxidants and epilepsy risk, we conducted a two-sample Mendelian randomization (MR) analysis. This involved examining antioxidants such as zinc, selenium, α- and γ-tocopherol, vitamin A (retinol), vitamin C (ascorbate), and vitamin E (α-tocopherol). We utilized instrumental variables (IVs) which were genetic variations highly associated with these commonly used antioxidants. Exposure data were sourced from a comprehensive genome-wide association study (GWAS). We aggregated data from the International League Against Epilepsy (ILAE) Consortium sample, which included various types of epilepsy, as an outcome variable. Finally, we applied the inverse variance weighting method and conducted sensitivity analyses for further validation.

Results

Based on the primary MR estimates and subsequent sensitivity analyses, the inverse variance weighting (IVW) method revealed that a genetically predicted increase in zinc per standard deviation was positively associated with three types of epilepsy. This includes all types of epilepsy (OR = 1.06, 95% CI: 1.02-1.11, p = 0.008), generalized epilepsy (OR = 1.13, 95% CI: 1.01-1.25, p = 0.030), and focal epilepsy (documented hippocampal sclerosis) (OR = 1.01, 95% CI: 1.00-1.02, p = 0.025). However, there is no evidence indicating that other antioxidants obtained from the diet affect the increase of epilepsy either positively or negatively.

Conclusion

Our research indicates that the risk of developing epilepsy may be directly linked to the genetic prediction of zinc, whereas no such association was found for other antioxidants.

Propofol mitigates brain injury and oxidative stress, and enhances GABAA receptor α1 subunit expression in a rat model of lithium chloride-pilocarpine induced status epilepticus

Background/aim

Propofol is a positive allosteric modulator of GABAA receptor (GABAAR) and has potent antioxidant activity. The aim of this study was to investigate the effect of propofol on damage to the cerebral cortex and hippocampus in a lithium chloride (LiCl)-pilocarpine animal model of status epilepticus (SE).

Materials and methods

Adult male Sprague Dawley rats were injected with LiCl-pilocarpine to induce SE. They were then randomized and injected 30 min later with vehicle saline (SE+saline), propofol (SE+PPF, 50 mg/kg), Diazepam (SE+DZP, 10 mg/kg), Scopolamine (SE+SCOP, 10 mg/kg), or MK-801 (SE+MK-801, 2 mg/kg). Another group of rats received saline only and served as the naïve control (BLK). The levels of superoxide dismutase (SOD), glutathione (GSH) and malondialdehyde (MDA) in the serum, cortex and hippocampus were analyzed 2 and 24 h posttreatment. The degree of tissue damage in the cortex and hippocampus of individual rats was assessed 24 h posttreatment, together with expression of the GABAAR α1 subunit.

Results

The propofol group showed reduced levels of tissue damage in the cerebral cortex and hippocampus, decreased levels of MDA, and increased levels of GSH compared to the SE+saline group. No changes in SOD level were observed in serum and tissue samples from the cortex and hippocampus of SE+saline rats. Immunohistochemistry and Western blot assays showed that propofol treatment significantly increased the expression of GABAAR α1 subunit in the cortical and hippocampal tissues of SE rats.

Conclusion

Propofol treatment protected against SE-induced tissue injury in the cortex and hippocampus of rats. This was due at least in part to its antioxidant activity and to its induction of GABAAR α1 subunit expression in the brain.

Therapeutic Strategies to Ameliorate Neuronal Damage in Epilepsy by Regulating Oxidative Stress, Mitochondrial Dysfunction, and Neuroinflammation

Epilepsy is a central nervous system disorder involving spontaneous and recurring seizures that affects 50 million individuals globally. Because approximately one-third of patients with epilepsy do not respond to drug therapy, the development of new therapeutic strategies against epilepsy could be beneficial. Oxidative stress and mitochondrial dysfunction are frequently observed in epilepsy. Additionally, neuroinflammation is increasingly understood to contribute to the pathogenesis of epilepsy. Mitochondrial dysfunction is also recognized for its contributions to neuronal excitability and apoptosis, which can lead to neuronal loss in epilepsy. This review focuses on the roles of oxidative damage, mitochondrial dysfunction, NAPDH oxidase, the blood-brain barrier, excitotoxicity, and neuroinflammation in the development of epilepsy. We also review the therapies used to treat epilepsy and prevent seizures, including anti-seizure medications, anti-epileptic drugs, anti-inflammatory therapies, and antioxidant therapies. In addition, we review the use of neuromodulation and surgery in the treatment of epilepsy. Finally, we present the role of dietary and nutritional strategies in the management of epilepsy, including the ketogenic diet and the intake of vitamins, polyphenols, and flavonoids. By reviewing available interventions and research on the pathophysiology of epilepsy, this review points to areas of further development for therapies that can manage epilepsy.

N-acetylcysteine aggravates seizures while improving depressive-like and cognitive impairment comorbidities in the WAG/Rij rat model of absence epilepsy

N-acetylcysteine (NAC) is an antioxidant with some demonstrated efficacy in a range of neuropsychiatric disorders. NAC has shown anticonvulsant effects in animal models. NAC effects on absence seizures are still not uncovered, and considering its clinical use as a mucolytic in patients with lung diseases, people with epilepsy are also likely to be exposed to the drug. Therefore, we aimed to study the effects of NAC on absence seizures in the WAG/Rij rat model of absence epilepsy with neuropsychiatric comorbidities. The effects of NAC chronic treatment in WAG/Rij rats were evaluated on: absence seizures at 15 and 30 days by EEG recordings and animal behaviour at 30 days on neuropsychiatric comorbidities. Furthermore, the mechanism of action of NAC was evaluated by analysing brain expression levels of some possible key targets: the excitatory amino acid transporter 2, cystine-glutamate antiporter, metabotropic glutamate receptor 2, the mechanistic target of rapamycin and p70S6K as well as levels of total glutathione. Our results demonstrate that in WAG/Rij rats, NAC treatment significantly increased the number and duration of SWDs, aggravating absence epilepsy while ameliorating neuropsychiatric comorbidities. NAC treatment was linked to an increase in brain mGlu2 receptor expression with this being likely responsible for the observed absence seizure-promoting effects. In conclusion, while confirming the positive effects on animal behaviour induced by NAC also in epileptic animals, we report the aggravating effects of NAC on absence seizures which could have some serious consequences for epilepsy patients with the possible wider use of NAC in clinical therapeutics.

Increased Oxidative Stress Toxicity and Lowered Antioxidant Defenses in Temporal Lobe Epilepsy and Mesial Temporal Sclerosis: Associations with Psychiatric Comorbidities

Oxidative stress toxicity (OSTOX), as well as lowered antioxidant defenses (ANTIOX), plays a role in temporal lobe epilepsy (TLE). Nevertheless, the associations between OSTOX/ANTIOX and psychiatric comorbidities in TLE are largely unknown. Thus, this study examines plasma malondialdehyde (MDA), lipid hydroperoxides (LOOH), advanced oxidation protein products (AOPP), nitric oxide metabolites (NO_x), total radical-trapping antioxidant parameter (TRAP), and sulfhydryl (-SH) groups in depression due to TLE (n = 25); anxiety disorders due to TLE (n = 27); psychotic disorder due to TLE (n = 25); "pure TLE" (n = 27); and healthy controls (n = 40). TLE and mesial temporal sclerosis (MTS) were characterized by significant increases in OSTOX (MDA, AOPP, LOOH) and lowered ANTIOX (-SH groups, TRAP). The discrimination of pure TLE from controls yielded a significant area under the ROC curve for MDA (0.999), AOPP (0.851), -SH groups (0.899), and the OSTOX/ANTIOX ratio (0.996). Seizure frequency is significantly associated with increased MDA and lowered LOOH and NO_x levels. Increased MDA was associated with the severity of depressive and physiosomatic symptoms, while increased AOPP levels predicted suicidal ideation. Depression and anxiety disorders co-occurring with TLE showed significantly lower MDA levels than TLE without any comorbidities. The psychotic and negative symptoms of TLE are associated with increased MDA levels and excitation with increased LOOH and lowered TRAP levels. These results indicate that oxidative stress toxicity especially protein oxidation and aldehyde formation coupled with lowered -SH groups plays a key role in the pathophysiology of TLE/MTS. Increased aldehyde formation also impacts psychopathology and psychosis, as well as negative and depressive symptoms.

Determination of levels of oxidative stress and nitrosative stress in patients with epilepsy

BACKGROUND

Epilepsy is one of the most common neurological diseases. The underlying pathophysiological mechanisms in epilepsy are still unknown. Oxidative stress is believed to be one of the factors involved in the pathogenesis of epileptogenesis. In various pathophysiological conditions, reactive nitrogen species (RNS) such as nitrogen and peroxynitrite are produced and these RNSs can bind to free nucleosides and nucleotides or to nucleosides and nucleotides existing in the DNA/RNA structure. 8-Nitroguanine (8-NG) is a typical DNA nucleobase product of nitrosative damage generated by RNS. It has been proposed that F2-isoprostanes, in particular 8-iso-Prostaglandin F2α (8-isoPGF2α), are specific, reliable and non-invasive biomarkers of lipid peroxidation in vivo. In the present study, we compared the levels of lipid oxidative stress biomarker 8-isoPGF2α and nitrosative stress DNA biomarker 8-NG in patients with epilepsy undergoing antiepileptic drug (AEDs) treatment and with those in healthy participants.

METHODS

The present study comprised 90 patients aged between 17 and 53 who were admitted to the Neurology Clinic of Cumhuriyet University and diagnosed with epilepsy. The patients were assigned into the intervention (n = 45) and control (n = 45) groups. Of the participants in the intervention group, 37.7% (n = 17) were treated with levetiracetam (LEV), 33.3% (n = 15) with valproic acid (VA) and 29% (n = 13) with carbamazepine. Serum 8-iso-PGF2α and 8-NG levels of the participants in the intervention and control groups were determined by ELISA.

RESULTS

There was no significant difference between the medication (LEV, VA, Carbamazepine) used by the participants and their 8-iso-PGF2α and 8-NG levels (p > 0.05). However, 8-iso-PGF2α and 8-NG were significantly higher in the participants in the intervention than in the participants in the control group (p < 0.001).

CONCLUSION

Our study demonstrated that there was an increase in oxidative and nitrosative stres markers in patients with epilepsy. There was no significant difference between the 8-iso-PGF2α and 8-NG levels of the participants taking three different AEDs.

The Role of NMDA Receptors in the Effect of Purinergic P2X7 Receptor on Spontaneous Seizure Activity in WAG/Rij Rats With Genetic Absence Epilepsy

P2X7 receptors (P2X7Rs) are ATP sensitive cation channels and have been shown to be effective in various epilepsy models. Absence epilepsy is a type of idiopathic, generalized, non-convulsive epilepsy. Limited data exist on the role of P2X7Rs and no data has been reported regarding the interaction between P2X7Rs and glutamate receptor NMDA in absence epilepsy. Thus, this study was designed to investigate the role of P2X7 and NMDA receptors and their possible interaction in WAG/Rij rats with absence epilepsy. Permanent cannula and electrodes were placed on the skulls of the animals. After the healing period of the electrode and cannula implantation, ECoG recordings were obtained during 180 min before and after drug injections. P2X7R agonist BzATP, at doses of 50 μg and 100 μg (intracerebroventricular; i.c.v.) and antagonist A-438079, at doses of 20 μg and 40 μg (i.c.v.) were administered alone or prior to memantine (5 mg/kg, intraperitoneal; i.p.) injection. The total number (in every 20 min), the mean duration, and the amplitude of spike-wave discharges (SWDs) were calculated and compared. Rats were decapitated and the right and left hemisphere, cerebellum, and brainstem were separated for the measurements of the advanced oxidation protein product (AOPP), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), glutathione peroxide (GPx), and glutathione reductase (GR). BzATP and A-438079 did not alter measured SWDs parameters, whereas memantine reduced them, which is considered anticonvulsant. BzATP did not alter the anticonvulsant effect of memantine, while A-438079 decreased the effect of memantine. Administration of BzATP increased the levels of SOD and GR in cerebrum hemispheres. A-438079 did not alter any of the biochemical parameters. Memantine reduced the levels of MDA, GSH, and GR while increased the level of CAT in the cerebrum. Administration of BzATP before memantine abolished the effect of memantine on MDA levels. The evidence from this study suggests that P2X7Rs does not directly play a role in the formation of absence seizures. P2X7Rs agonist, reduced the antioxidant activity of memantine whereas agonist of P2X7Rs reduced the anticonvulsant action of memantine, suggesting a partial interaction between P2X7 and NMDA receptors in absence epilepsy model.

2,4 Dinitrophenol as Medicine

In the sanctity of pure drug discovery, objective reasoning can become clouded when pursuing ideas that appear unorthodox, but are spot on physiologically. To put this into historical perspective, it was an unorthodox idea in the 1950’s to suggest that warfarin, a rat poison, could be repositioned into a breakthrough drug in humans to protect against strokes as a blood thinner. Yet it was approved in 1954 as Coumadin^® and has been prescribed to billions of patients as a standard of care. Similarly, no one can forget the horrific effects of thalidomide, prescribed or available without a prescription, as both a sleeping pill and “morning sickness” anti-nausea medication targeting pregnant women in the 1950’s. The “thalidomide babies” became the case-in-point for the need of strict guidelines by the U.S. Food & Drug Administration (FDA) or full multi-species teratogenicity testing before drug approval. More recently it was found that thalidomide is useful in graft versus host disease, leprosy and resistant tuberculosis treatment, and as an anti-angiogenesis agent as a breakthrough drug for multiple myeloma (except for pregnant female patients). Decades of diabetes drug discovery research has historically focused on every possible angle, except, the energy-out side of the equation, namely, raising mitochondrial energy expenditure with chemical uncouplers. The idea of “social responsibility” allowed energy-in agents to be explored and the portfolio is robust with medicines of insulin sensitizers, insulin analogues, secretagogues, SGLT2 inhibitors, etc., but not energy-out medicines. The primary reason? It appeared unorthodox, to return to exploring a drug platform used in the 1930s in over 100,000 obese patients used for weight loss. This is over 80-years ago and prior to Dr Peter Mitchell explaining the mechanism of how mitochondrial uncouplers, like 2,4-dinitrophenol (DNP) even worked by three decades later in 1961. Although there is a clear application for metabolic disease, it was not until recently that this platform was explored for its merit at very low, weight-neutral doses, for treating insidious human illnesses and completely unrelated to weight reduction. It is known that mitochondrial uncouplers specifically target the entire organelle’s physiology non-genomically. It has been known for years that many neuromuscular and neurodegenerative diseases are associated with overt production of reactive oxygen species (ROSs), a rise in isoprostanes (biomarker of mitochondrial ROSs in urine or blood) and poor calcium (Ca²⁺) handing. It has also been known that mitochondrial uncouplers lower ROS production and Ca²⁺ overload. There is evidence that elevation of isoprostanes precedes disease onset, in Alzheimer’s Disease (AD). It is also curious, why so many neurodegenerative diseases of known and unknown etiology start at mid-life or later, such as Multiple Sclerosis (MS), Huntington Disease (HD), AD, Parkinson Disease, and Amyotrophic Lateral Sclerosis (ALS). Is there a relationship to a buildup of mutations that are sequestered over time due to ROSs exceeding the rate of repair? If ROS production were managed, could disease onset due to aging be delayed or prevented? Is it possible that most, if not all neurodegenerative diseases are manifested through mitochondrial dysfunction? Although DNP, a historic mitochondrial uncoupler, was used in the 1930s at high doses for obesity in well over 100,000 humans, and so far, it has never been an FDA-approved drug. This review will focus on the application of using DNP, but now, repositioned as a potential disease-modifying drug for a legion of insidious diseases at much lower and paradoxically, weight neutral doses. DNP will be addressed as a treatment for “metabesity”, an emerging term related to the global comorbidities associated with the over-nutritional phenotype; obesity, diabetes, nonalcoholic steatohepatitis (NASH), metabolic syndrome, cardiovascular disease, but including neurodegenerative disorders and accelerated aging. Some unexpected drug findings will be discussed, such as DNP’s induction of neurotrophic growth factors involved in neuronal heath, learning and cognition. For the first time in 80’s years, the FDA has granted (to Mitochon Pharmaceutical, Inc., Blue Bell, PA, USA) an open Investigational New Drug (IND) approval to begin rigorous clinical testing of DNP for safety and tolerability, including for the first ever, pharmacokinetic profiling in humans. Successful completion of Phase I clinical trial will open the door to explore the merits of DNP as a possible treatment of people with many truly unmet medical needs, including those suffering from HD, MS, PD, AD, ALS, Duchenne Muscular Dystrophy (DMD), and Traumatic Brain Injury (TBI).

Isoprostanes, neuroprostanes and phytoprostanes: An overview of 25years of research in chemistry and biology

Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology. In recent years, it has become accepted that these molecules not only serve as markers of oxidative damage but also exhibit a wide range of bioactivities. In addition, isoprostanoids have emerged as indicators of oxidative stress in humans and their environment. This review explores in detail the isoprostanoid chemistry and biology that has been achieved in the past three decades.

Scavenging of highly reactive gamma-ketoaldehydes attenuates cognitive dysfunction associated with epileptogenesis

Cognitive dysfunction is a major comorbidity of the epilepsies; however, treatments targeting seizure-associated cognitive dysfunction, particularly deficits in learning and memory are not available. Isoketals and neuroketals, collectively known as gamma-ketoaldehydes are formed via the non-enzymatic, free radical catalyzed oxidation of arachidonic acid and docosahexaenoic acid, respectively. They are attractive candidates for oxidative protein damage and resultant cognitive dysfunction due to their formation within the plasma membrane and their high proclivity to form cytotoxic adducts on protein lysine residues. We tested the hypothesis that gamma-ketoaldehydes mechanistically contribute to seizure-associated memory impairment using a specific gamma-ketoaldehyde scavenger, salicylamine in the kainic acid and pilocarpine rat models of temporal lobe epilepsy. We show that gamma-ketoaldehydes are increased following epileptogenic injury in hippocampus and perirhinal cortex, two brain regions imperative for learning and memory. Treatment with an orally bioavailable, brain permeable scavenger, salicylamine attenuated 1) spatial memory deficits 2) reference memory deficits and 3) neuronal loss and astrogliosis in two mechanistically distinct models of epilepsy without affecting the epileptogenic injury or the development of chronic epilepsy. We have previously demonstrated that reactive oxygen species and the lipid peroxidation biomarkers, F₂-isoprostanes are produced following status epilepticus. However, which reactive species specifically mediate oxidative damage to cellular macromolecules remains at large. We provide novel data suggesting that memory impairment occurs via gamma-ketoaldehyde production in two models of epilepsy and that treatment with a gamma-ketoaldehyde scavenger can protect vulnerable neurons. This work suggests a novel target and therapy to treat seizure-induced memory deficits in epilepsy.

WONOEP appraisal: Molecular and cellular biomarkers for epilepsy

Peripheral biomarkers have myriad potential uses for treatment, prediction, prognostication, and pharmacovigilance in epilepsy. To date, no single peripheral biomarker has demonstrated proven effectiveness, although multiple candidates are in development. In this review, we discuss the major areas of focus including inflammation, blood-brain barrier dysfunction, redox alterations, metabolism, hormones and growth factors.

Antiepileptic drugs affect lipid oxidative markers- neuroprostanes and F2-dihomo-isoprostanes- in patients with epilepsy: differences among first-, second-, and third-generation drugs by UHPLC-QqQ-MS/MS

This work show that treatment with new-generation AEDs reduces the excretion of NeuroPs/F₂-dihomo-IsoPs to values similar to those in the control group, indicating a positive effect of these AEDs on the antioxidant status of epileptic patients.

Montelukast inhibits pentylenetetrazol-induced seizures in rats

Background

Montelukast is an antiinflammatory drug with an antioxidant property. In this study, we aimed to reveal whether montelukast has a preventive effect against seizures and post-seizure oxidative stress in pentylenetetrazol (PTZ)-induced seizures in rats.

Material/Methods

Of the 48 male Sprague-Dawley rats used in the study, 24 were assigned to EEG recordings (group A) and 24 were assigned to behavioral studies (group B). In group A, the electrodes were implanted on dura over the left frontal cortex for EEG recording. After 10 days, in group A, i.p. saline, 25, 50, or 100 mg/kg montelukast+35 mg/kg PTZ was administered to the rats. EEG was recorded and spike percentage was evaluated. In group B, i.p. saline, 25, 50, or 100 mg/kg montelukast+70 mg/kg PTZ was administered to the rats. Racine’s Convulsion Scale (RCS) and onset times of first myoclonic jerk (FMJ) was used to evaluate the seizures. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined in the brain tissue of animals.

Results

Animals treated with 50 or 100 mg/kg montelukast had significantly lower RCS and significantly increased FMJ onset time compared to the saline-treated animals. Moreover, groups given 25, 50, or 100 mg/kg montelukast had significantly lower MDA and higher SOD levels compared to the saline-treated group. The differences were more pronounced in the 100 mg/kg montelukast-pretreated group (p<0.001).

Conclusions

Montelukast showed anticonvulsant action and led to amelioration of oxidative stress markers in PTZ-induced seizures in rats.

F2-isoprostanes: a measure of oxidative stress in children receiving treatment for leukemia

Acute lymphoblastic leukemia (ALL) is the most prevalent and curable cancer among children and adolescents less than 15 years of age in the United States. Essential for cure of childhood ALL is prophylactic treatment of the central nervous system (CNS), with methotrexate (MTX) being the most widely used drug in this treatment. While CNS treatment has contributed to long-term disease-free survival, resulting declines in academic abilities have been reported. There is growing evidence that CNS treatment with MTX increases oxidative stress, a potential mechanism of CNS injury. This article reports changes in oxidative stress, measured by the biomarker F2-isoprostane (F2-IsoP), in the cerebrospinal fluid (CSF) in 47 children with ALL during the first 18 months of treatment. The number of CSF samples ranged from 5 to 14 during postinduction and from 1 to 9 during continuation. Total doses of intrathecal MTX during postinduction were significantly correlated with the mean and highest concentrations of F2-IsoP during postinduction and the mean concentration of F2-IsoP during continuation. F2-IsoP concentrations during postinduction and continuation were higher in children who received more than six doses of intrathecal MTX. New therapies for a highly curable disease such as childhood leukemia have the potential to be individualized in the future, requiring reliable molecular and biochemical markers, such as oxidative stress indicators. Innovative use of biomarkers has the potential to increase our understanding of treatment-related toxicities and associated symptoms and to inform future therapeutic approaches for optimizing cure and quality of life among children with leukemia.

The use of cortical spreading depression for studying the brain actions of antioxidants

OBJECTIVES

We review the main adverse effects of reactive oxygen species (ROS) in the mammalian organism, introducing the reader on the worldwide problem of the ROS neurophysiological impact on the developing and the adult brain, and discussing the neuroprotective action of antioxidant molecules.

METHODS

We briefly present the electrophysiological phenomenon designated as 'cortical spreading depression' (CSD), as a parameter of normal brain functioning. We highlight recent electrophysiological advances obtained in experimental studies from our laboratory and from others, showing how to investigate the ROS effects on the brain by using the CSD phenomenon.

RESULTS

Under conditions such as aging, ROS production by photo-activation of dye molecules and ethanol consumption, we describe the effects, on CSD, of treating animals with (1) antioxidants and (2) with antioxidant-deficient diets.

DISCUSSION

The current understanding of how ROS affect brain electrophysiological activity and the possible interaction between these ROS effects and those effects of altered nutritional status of the organism are discussed.