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Inflammation has been identified as an important mediator of seizures and epileptogenesis. Understanding the mechanisms underlying seizure-induced neuroinflammation could lead to the development of novel therapies for the epilepsies. Reactive oxygen species (ROS) are recognized as mediators of seizure-induced neuronal damage and are known to increase in models of epilepsies. ROS are also known to contribute to inflammation in several disease states. We hypothesized that ROS are key modulators of neuroinflammation i.e. pro-inflammatory cytokine production and microglial activation in acquired epilepsy. The role of ROS in modulating seizure-induced neuroinflammation was investigated in the pilocarpine model of temporal lobe epilepsy (TLE). Pilocarpine-induced status epilepticus (SE) resulted in a time-dependent increase in pro-inflammatory cytokine production in the hippocampus and piriform cortex. Scavenging ROS with a small-molecule catalytic antioxidant decreased SE-induced pro-inflammatory cytokine production and microglial activation, suggesting that ROS contribute to SE-induced neuroinflammation. Scavenging ROS also attenuated phosphorylation of ribosomal protein S6, the downstream target of the mammalian target of rapamycin (mTOR) pathway indicating that this pathway might provide one mechanistic link between SE-induced ROS production and inflammation. Together, these results demonstrate that ROS contribute to SE-induced cytokine production and antioxidant treatment may offer a novel approach to control neuroinflammation in epilepsy. [ABSTRACT FROM AUTHOR]

Reactive oxygen species are a well-defined therapeutic target for Parkinson's disease (PD) and pharmacological agents that catalytically scavenge reactive species are promising neuroprotective strategies for treatment. Metalloporphyrins are synthetic catalytic antioxidants that mimic the body's own antioxidant enzymes i.e. superoxide dismutases and catalase. The goal of this study was to determine if newly designed metalloporphyrins have enhanced pharmacodynamics including oral bioavailability, longer plasma elimination half-lives, penetrate the blood brain barrier, and show promise for PD treatment. Three metalloporphyrins (AEOL 11216, AEOL 11203 and AEOL 11114) were identified in this study as potential candidates for further pre-clinical development. Each of these compounds demonstrated blood brain barrier permeability by the i.p. route and two of three compounds (AEOL 11203 and AEOL 11114) were orally bioavailable. All of these compounds protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity, including dopamine depletion in the striatum, dopaminergic neuronal loss in the substantial nigra, and increased oxidative/nitrative stress indices (glutathione disulfide and 3-nitrotyrosine) in the ventral midbrain of the mice without inhibiting MPTP metabolism. Daily therapeutic dosing of these metalloporphyrins were well tolerated without accumulation of brain manganese levels or behavioral alterations assessed by open field and rotarod tests. The study identified two orally active metalloporphyrins and one injectable metalloporphyrin as clinical candidates for further development in PD. [ABSTRACT FROM AUTHOR]

Metabolic alterations have been implicated in the etiology of temporal lobe epilepsy (TLE), but whether or not they have a functional impact on cellular energy producing pathways (glycolysis and/or oxidative phosphorylation) is unknown. The goal of this study was to determine if alterations in cellular bioenergetics occur using real-time analysis of mitochondrial oxygen consumption and glycolytic rates in an animal model of TLE. We hypothesized that increased steady-state levels of reactive oxygen species (ROS) initiated by epileptogenic injury result in impaired mitochondrial respiration. We established methodology for assessment of bioenergetic parameters in isolated synaptosomes from the hippocampus of Sprague–Dawley rats at various times in the kainate (KA) model of TLE. Deficits in indices of mitochondrial respiration were observed at time points corresponding with the acute and chronic phases of epileptogenesis. We asked if mitochondrial bioenergetic dysfunction occurred as a result of increased mitochondrial ROS and if it could be attenuated in the KA model by pharmacologically scavenging ROS. Increased steady-state ROS in mice with forebrain-specific conditional deletion of manganese superoxide dismutase (Sod2 fl / fl NEX Cre / Cre ) in mice resulted in profound deficits in mitochondrial oxygen consumption. Pharmacological scavenging of ROS with a catalytic antioxidant restored mitochondrial respiration deficits in the KA model of TLE. Together, these results demonstrate that mitochondrial respiration deficits occur in experimental TLE and ROS mechanistically contribute to these deficits. Furthermore, this study provides novel methodology for assessing cellular metabolism during the entire time course of disease development. [ABSTRACT FROM AUTHOR]

Abstract: Steady-state levels of reactive oxygen species (ROS) and oxidative damage to cellular macromolecules are increased in the rodent hippocampus during epileptogenesis. However, the role of reactive nitrogen species (RNS) in epileptogenesis remains to be explored. The goal of this study was to determine the spatial and temporal occurrence of RNS i.e. nitric oxide levels in a rat model of temporal lobe epilepsy (TLE). Rats were injected with a single high dose of kainate and monitored by video for behavioral seizures for 6weeks to determine the onset and severity of chronic seizures. RNS and tissue/mitochondrial redox status (glutathione redox couple and coenzyme A:glutathione redox couple) were measured in the hippocampus at 8h, 24h, 48h, 1wk, 3wk and 6wk following kainate to assess the level of reactive species in subcellular compartments. We observed a biphasic increase in RNS levels with a return to control values at the 48h time point. However, both tissue and mitochondrial redox status showed permanent and significant decreases during the entire time course of epilepsy development. 3 nitrotyrosine (3NT) protein adducts were found to gradually increase throughout epileptogenesis, conceivably as a result of the local environment under oxidative and nitrosative stress. Colocalization of 3NT immunostaining with neuron- or astrocyte-specific markers revealed neuron-specific localization of 3NT in hippocampal principal neurons. Persistent and concurrent glutathione oxidation and nitrosative stress occur during epileptogenesis suggesting a favorable environment for posttranslational modifications. [Copyright &y& Elsevier]

Abstract: Epileptic seizures are a common feature associated with inherited mitochondrial diseases. This study investigated the role of mitochondrial oxidative stress in epilepsy resulting from mitochondrial dysfunction using cross-bred mutant mice lacking mitochondrial manganese superoxide dismutase (MnSOD or SOD2) and a lipophilic metalloporphyrin catalytic antioxidant. Video-EEG monitoring revealed that in the second to third week of postnatal life (P14-P21) B6D2F2 Sod2 −/− mice exhibited frequent spontaneous motor seizures providing evidence that oxidative stress-induced mitochondrial dysfunction may contribute to epileptic seizures. To confirm the role of mitochondrial oxidative stress in epilepsy a newly developed lipophilic metalloporphyrin, AEOL 11207, with high potency for catalytic removal of endogenously generated reactive oxygen species was utilized. AEOL 11207-treated Sod2 −/− mice showed a significant decrease in both the frequency and duration of spontaneous seizures but no effect on seizure severity. A significant increase in the average lifespan of AEOL 11207-treated Sod2 −/− mice compared to vehicle-treated Sod2 −/− mice was also observed. Indices of mitochondrial oxidative stress and damage (aconitase inactivation, 3-nitrotyrosine formation, and depletion of reduced coenzyme A) and ATP levels affecting neuronal excitability were significantly attenuated in the brains of AEOL 11207-treated Sod2 −/− mice compared to vehicle-treated Sod2 −/− mice. The occurrence of epileptic seizures in Sod2 −/− mice and the ability of catalytic antioxidant therapy to attenuate seizure activity, mitochondrial dysfunction, and ATP levels suggest that ongoing mitochondrial oxidative stress can contribute to epilepsy associated with mitochondrial dysfunction and disease. [Copyright &y& Elsevier]

Abstract: The mechanisms underlying the efficacy of the ketogenic diet (KD) remain unknown. Recently, we showed that the KD increased glutathione (GSH) biosynthesis. Since the NF E2-related factor 2 (Nrf2) transcription factor is a primary responder to cellular stress and can upregulate GSH biosynthesis, we asked whether the KD activates the Nrf2 pathway. Here we report that rats consuming a KD show acute production of H2O2 from hippocampal mitochondria, which decreases below control levels by 3weeks, suggestive of an adaptive response. 4-Hydroxy-2-nonenal (4-HNE), an electrophilic lipid peroxidation end product known to activate the Nrf2 detoxification pathway, was also acutely increased by the KD. Nrf2 nuclear accumulation was evident in both the hippocampus and liver, and the Nrf2 target, NAD(P)H:quinone oxidoreductase (NQO1), exhibited increased activity in both the hippocampus and liver after 3weeks. We also found chronic depletion of liver tissue GSH, while liver mitochondrial antioxidant capacity was preserved. These data suggest that the KD initially produces mild oxidative and electrophilic stress, which may systemically activate the Nrf2 pathway via redox signaling, leading to chronic cellular adaptation, induction of protective proteins, and improvement of the mitochondrial redox state. [ABSTRACT FROM AUTHOR]

Abstract: Oxidative stress and mitochondrial dysfunction are acute consequences of status epilepticus (SE). However, the role of mitochondrial oxidative stress and genomic instability during epileptogenesis remains unknown. Using the kainate animal model of temporal lobe epilepsy, we investigated oxidative mitochondrial DNA (mtDNA) damage and changes in the mitochondrial base excision repair pathway (mtBER) in the rat hippocampus for a period of 3 months after SE. Acute seizure activity caused a time-dependent increase in mitochondrial, but not nuclear 8-hydroxy-2-deoxyguanosine (8-OHdG/2dG) levels and a greater frequency of mtDNA lesions. This was accompanied by increased mitochondrial H2O2 production and a transient decrease in mtDNA repair capacity. The mtBER proteins 8-oxoguanine glycosylase (Ogg1) and DNA polymerase gamma (Pol γ) demonstrated elevated expression at mRNA and protein levels shortly after SE and this was followed by a gradual improvement in mtDNA repair capacity. Recurrent seizures associated with the chronic phase of epilepsy coincided with the accumulation of mtDNA damage, increased mitochondrial H2O2 levels, decreased expression of Ogg1 and Pol γ and impaired mtDNA repair capacity. Together, increased oxidative mtDNA damage, mitochondrial H2O2 production and alterations in the mtBER pathway provide evidence for mitochondrial oxidative stress in epilepsy and suggest that mitochondrial injury may contribute to epileptogenesis. [Copyright &y& Elsevier]

Abstract: Decreased glutathione levels associated with increased oxidative stress are a hallmark of numerous neurodegenerative diseases, including Parkinson''s disease. GSH is an important molecule that serves as an anti-oxidant and is also a major determinant of cellular redox environment. Previous studies have demonstrated that neurotoxins can cause changes in reduced and oxidized GSH levels; however, information regarding steady state levels remains unexplored. The goal of this study was to characterize changes in cellular GSH levels and its regulatory enzymes in a dopaminergic cell line (N27) following treatment with the Parkinsonian toxin, 1-methyl-4-phenylpyridinium (MPP+). Cellular GSH levels were initially significantly decreased 12 h after treatment, but subsequently recovered to values greater than controls by 24 h. However, oxidized glutathione (GSSG) levels were increased 24 h following treatment, concomitant with a decrease in GSH/GSSG ratio prior to cell death. In accordance with these changes, ROS levels were also increased, confirming the presence of oxidative stress. Decreased enzymatic activities of glutathione reductase and glutamate–cysteine ligase by 20–25% were observed at early time points and partly account for changes in GSH levels after MPP+ exposure. Additionally, glutathione peroxidase activity was increased 24 h following treatment. MPP+ treatment was not associated with increased efflux of glutathione to the medium. These data further elucidate the mechanisms underlying GSH depletion in response to the Parkinsonian toxin, MPP+. [Copyright &y& Elsevier]

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, F 2 -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. [ABSTRACT FROM AUTHOR]

Cognitive dysfunction is an important comorbidity of temporal lobe epilepsy (TLE). However, no targeted therapies are available and the mechanisms underlying cognitive impairment, specifically deficits in learning and memory associated with TLE remain unknown. Oxidative stress is known to occur in the pathogenesis of TLE but its functional role remains to be determined. Here, we demonstrate that oxidative stress and resultant processes contribute to cognitive decline associated with epileptogenesis. Using a synthetic catalytic antioxidant, we show that pharmacological removal of reactive oxygen species (ROS) prevents 1) oxidative stress, 2) deficits in mitochondrial oxygen consumption rates, 3) hippocampal neuronal loss and 4) cognitive dysfunction without altering the intensity of the initial status epilepticus (SE) or epilepsy development in a rat model of SE-induced TLE. Moreover, the effects of the catalytic antioxidant on cognition persisted beyond the treatment period suggestive of disease-modification. The data implicate oxidative stress as a novel mechanism by which cognitive dysfunction can arise during epileptogenesis and suggest a potential disease-modifying therapeutic approach to target it. [ABSTRACT FROM AUTHOR]

Mitochondrial superoxide (O 2 −) production is implicated in aging, neurodegenerative disease, and most recently epilepsy. Yet the specific contribution of neuronal O 2 − to these phenomena is unclear. Here, we selectively deleted superoxide dismutase-2 (SOD2) in neuronal basic helix-loop-helix transcription factor (NEX)-expressing cells restricting deletion to a subset of excitatory principle neurons primarily in the forebrain (cortex and hippocampus). This resulted in nSOD2 KO mice that lived into adulthood (2–3 months) with epilepsy, selective loss of neurons, metabolic rewiring and a marked mitohormetic gene response. Surprisingly, expression of an astrocytic gene, glial fibrillary acidic protein (GFAP) was significantly increased relative to WT. Further studies in rat primary neuron-glial cultures showed that increased mitochondrial O 2 −, specifically in neurons, was sufficient to upregulate GFAP. These results suggest that neuron-specific mitochondrial O 2 − is sufficient to drive a complex and catastrophic epileptic phenotype and highlights the ability of SOD2 to act in a cell-nonautonomous manner to influence an astrocytic response. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new dynamic compensation method based on system identification and error-overrun (EOV) mode correction is proposed to solve the problem that the existing dynamic compensation methods sometimes cannot improve the time-domain tracking performance and frequency-domain measurement bandwidth of the sensor simultaneously. • The new method divides the sensor dynamic compensation into primary compensation and secondary compensation. Primary compensation is to correct the overall frequency response of the sensor, secondary compensation is to purposely correct the remaining EOV modes that limit the sensor bandwidth. • Primary compensator is obtained by system identification method; secondary compensator is constructed in a unified structure of 2nd-order system. • Four categories of secondary compensators are proposed for correcting different EOV modes, and the effective secondary compensator is always available. The theoretical analysis and verification results show that the new method is effective, practical, and robust for sensor dynamic compensation. • According to the analysis in the article, a GUI identifier that integrates system identification, secondary compensator construction, dynamic performance evaluation and parameter fine-tuning can be easily developed and embedded in MATLAB to facilitate the utilization of the new method. To improve the dynamic performance of strain force sensor, a new dynamic compensation method based on system identification and error-overrun (EOV) mode correction is proposed to solve the problem that the existing methods though can improve the time-domain tracking performance but sometimes fail to widen the frequency-domain measurement bandwidth of the sensor simultaneously. For the new method, sensor dynamic compensation is divided into primary and secondary compensations. Primary compensator is obtained by system identification method for correcting the overall frequency response of the sensor, secondary compensators are constructed in a unified structure of 2nd-order system for purposely correcting the remaining EOV modes that limit the sensor measurement bandwidth. Specifically, construction methods of four categories of secondary compensators are discussed; circular construction of multiple secondary compensators and sequential dynamic compensation of sensor output are presented; last, an ATI Mini45 force/torque sensor is employed for verification. The results show that, the proposed method can shorten the step adjust times of the sensor six channels from up to hundreds of millisecond to within 3 ms and widen the bandwidths from around 30 Hz to over 100 Hz; and that, re-identifying a wideband primary compensator and constructing more secondary compensators can further improve the former indices to 0.45 ms and over 287 Hz for a channel. Consequently, the proposed method can effectively improve the time-domain tracking performance and measurement bandwidth of the sensor simultaneously, and it is proven to be effective, practical, and robust for sensor dynamic compensation. [ABSTRACT FROM AUTHOR]