Oxidative Stress Underlies the Ischemia/Reperfusion-Induced Internalization and Degradation of AMPA Receptors

DNA methyltransferase isoforms regulate endothelial cell exosome proteome composition

Extrinsic and intrinsic pathological stimuli in vascular disorders induce DNA methylation based epigenetic reprogramming in endothelial cells, which leads to perturbed gene expression and subsequently results in endothelial dysfunction (ED). ED is also characterized by release of exosomes with altered proteome leading to paracrine interactions in vasculature and subsequently contributing to manifestation, progression and severity of vascular complications. However, epigenetic regulation of exosome proteome is not known. Hence, our present study aimed to understand influence of DNA methylation on exosome proteome composition and their influence on endothelial cell (EC) function. DNMT isoforms (DNMT1, DNMT3A, and DNMT3B) were overexpressed using lentivirus in ECs. Exosomes were isolated and characterized from ECs overexpressing DNMT isoforms and C57BL/6 mice plasma treated with 5-aza-2'-deoxycytidine. 3D spheroid assay was performed to understand the influence of exosomes derived from cells overexpressing DNMTs on EC functions. Further, the exosomes were subjected to TMT labelled proteomics analysis followed by validation. 3D spheroid assay showed increase in the pro-angiogenic activity in response to exosomes derived from DNMT overexpressing cells which was impeded by inclusion of 5-aza-2'-deoxycytidine. Our results showed that exosome proteome and PTMs were significantly modulated and were associated with dysregulation of vascular homeostasis, metabolism, inflammation and endothelial cell functions. In vitro and in vivo validation showed elevated DNMT1 and TGF-β1 exosome proteins due to DNMT1 and DNMT3A overexpression, but not DNMT3B which was mitigated by 5-aza-2'-deoxycytidine indicating epigenetic regulation. Further, exosomes induced ED as evidenced by reduced expression of phospho-eNOSser1177. Our study unveils epigenetically regulated exosome proteins, aiding management of vascular complications.

Current evidence of synaptic dysfunction after stroke: Cellular and molecular mechanisms

BACKGROUND

Stroke is an acute cerebrovascular disease in which brain tissue is damaged due to sudden obstruction of blood flow to the brain or the rupture of blood vessels in the brain, which can prompt ischemic or hemorrhagic stroke. After stroke onset, ischemia, hypoxia, infiltration of blood components into the brain parenchyma, and lysed cell fragments, among other factors, invariably increase blood-brain barrier (BBB) permeability, the inflammatory response, and brain edema. These changes lead to neuronal cell death and synaptic dysfunction, the latter of which poses a significant challenge to stroke treatment.

RESULTS

Synaptic dysfunction occurs in various ways after stroke and includes the following: damage to neuronal structures, accumulation of pathologic proteins in the cell body, decreased fluidity and release of synaptic vesicles, disruption of mitochondrial transport in synapses, activation of synaptic phagocytosis by microglia/macrophages and astrocytes, and a reduction in synapse formation.

CONCLUSIONS

This review summarizes the cellular and molecular mechanisms related to synapses and the protective effects of drugs or compounds and rehabilitation therapy on synapses in stroke according to recent research. Such an exploration will help to elucidate the relationship between stroke and synaptic damage and provide new insights into protecting synapses and restoring neurologic function.

Exposure to tungsten particles via inhalation triggers early toxicity marker expression in the rat brain

OBJECTIVE

Our work is focused on tungsten, considered as an emerging contaminant. Its environmental dispersion is partly due to mining and military activities. Exposure scenario can also be occupational, in areas such as the hard metal industry and specific nuclear facilities. Our study investigated the cerebral effects induced by the inhalation of tungsten particles.

METHODS

Inhalation exposure campaigns were carried out at two different concentrations (5 and 80 mg/m3) in single and repeated modes (4 consecutive days) in adult rats within a nose-only inhalation chamber. Processes involved in brain toxicity were investigated 24 h after exposure.

RESULTS AND DISCUSSION

Site-specific effects in terms of neuroanatomy and concentration-dependent changes in specific cellular actors were observed. Results obtained in the olfactory bulb suggest a potential early effect on the survival of microglial cells. Depending on the mode of exposure, these cells showed a decrease in density accompanied by an increase in an apoptotic marker. An abnormal phenotype of the nuclei of mature neurons, suggesting neuronal suffering, was also observed in the frontal cortex, and can be linked to the involvement of oxidative stress. The differential effects observed according to exposure patterns could involve two components: local (brain-specific) and/or systemic. Indeed, tungsten, in addition to being found in the lungs and kidneys, was present in the brain of animals exposed to the high concentration.

CONCLUSION

Our data question the perceived innocuity of tungsten relative to other metals and raise hypotheses regarding possible adaptive or neurotoxic mechanisms that could ultimately alter neuronal integrity.

Extracts from Dendropanax morbifera leaves ameliorates cerebral ischemia-induced hippocampal damage by reducing oxidative damage in gerbil

AIM

In this study, we investigated the effects of Dendropanax morbifera extract (DME) on neuroprotection against ischemic damage in gerbils.

METHODS

DME (100 or 300 mg/kg) was orally administered to gerbils for three weeks, and 2 h after the last DME treatment, transient forebrain ischemia in the common carotid arteries was induced for 5 min. The forebrain ischemia-related cognitive impairments were assessed by spontaneous motor activity and passive avoidance test one and four days after ischemia, respectively. In addition, surviving and degenerating neurons were morphologically confirmed by neuronal nuclei immunohistochemical staining and Fluoro-Jade C staining, respectively, four days after ischemia. Changes of glial morphology were visualized by immunohistochemical staining for each marker such as glial fibrillary acidic protein and ionized calcium-binding protein. Oxidative stress was determined by measurements of dihydroethidium, O2· (formation of formazan) and malondialdehyde two days after ischemia. In addition, glutathione redox system such as reduced glutathione, oxidized glutathione levels, glutathione peroxidase, and glutathione reductase activities were measured two days after ischemia.

RESULTS

Spontaneous motor activity monitoring and passive avoidance tests showed that treatment with 300 mg/kg DME, but not 100 mg/kg, significantly alleviated ischemia-induced memory impairments. In addition, approximately 67 % of mature neurons survived and 29.3 % neurons were degenerated in hippocampal CA1 region four days after ischemia, and ischemia-induced morphological changes in astrocytes and microglia were decreased in the CA1 region after 300 mg/kg DME treatment. Furthermore, treatment with 300 mg/kg DME significantly ameliorated ischemia-induced oxidative stress, such as superoxide formation and lipid peroxidation, two days after ischemia. In addition, ischemia-induced reduction of the glutathione redox system in the hippocampus, assessed two days after the ischemia, was ameliorated by treatment with 300 mg/kg DME. These suggest that DME can potentially reduce ischemia-induced neuronal damage through its antioxidant properties.

Molecular Mechanisms of AMPA Receptor Trafficking in the Nervous System

Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.

Oxidative stress as a bridge between age and stroke: A narrative review

Stroke is the third most common cause of death globally and a leading cause of disability. The cellular and molecular changes following stroke and causes of neuronal death are not fully understood, and there are few effective treatments currently available. A rapid increase in the levels of reactive oxygen species (ROS) post stroke can overwhelm antioxidant defenses and trigger a series of pathophysiologic events including the inflammatory response, blood-brain barrier (BBB) disruption, apoptosis, and autophagy, ultimately leading to neuron degeneration and apoptosis. It is thought that beyond a certain age, the ROS accumulation resulting from stroke increases the risk of morbidity and mortality. In the present review, we summarize the role of oxidative stress (OS) as a link between aging and stroke pathogenesis. We also discuss how antioxidants can play a beneficial role in the prevention and treatment of stroke by eliminating harmful ROS, delaying aging, and alleviating damage to neurons.

Inhibiting NLRP3 inflammasome signaling pathway promotes neurological recovery following hypoxic-ischemic brain damage by increasing p97-mediated surface GluA1-containing AMPA receptors

BACKGROUND

The nucleotide-binding oligomeric domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is believed to be a key mediator of neuroinflammation and subsequent secondary brain injury induced by ischemic stroke. However, the role and underlying mechanism of the NLRP3 inflammasome in neonates with hypoxic-ischemic encephalopathy (HIE) are still unclear.

METHODS

The protein expressions of the NLRP3 inflammasome including NLRP3, cysteinyl aspartate specific proteinase-1 (caspase-1) and interleukin-1β (IL-1β), the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicacid receptor (AMPAR) subunit, and the ATPase valosin-containing protein (VCP/p97), were determined by Western blotting. The interaction between p97 and AMPA glutamate receptor 1 (GluA1) was determined by co-immunoprecipitation. The histopathological level of hypoxic-ischemic brain damage (HIBD) was determined by triphenyltetrazolium chloride (TTC) staining. Polymerase chain reaction (PCR) and Western blotting were used to confirm the genotype of the knockout mice. Motor functions, including myodynamia and coordination, were evaluated by using grasping and rotarod tests. Hippocampus-dependent spatial cognitive function was measured by using the Morris-water maze (MWM).

RESULTS

We reported that the NLRP3 inflammasome signaling pathway, such as NLRP3, caspase-1 and IL-1β, was activated in rats with HIBD and oxygen-glucose deprivation (OGD)-treated cultured primary neurons. Further studies showed that the protein level of the AMPAR GluA1 subunit on the hippocampal postsynaptic membrane was significantly decreased in rats with HIBD, and it could be restored to control levels after treatment with the specific caspase-1 inhibitor AC-YVAD-CMK. Similarly, in vitro studies showed that OGD reduced GluA1 protein levels on the plasma membrane in cultured primary neurons, whereas AC-YVAD-CMK treatment restored this reduction. Importantly, we showed that OGD treatment obviously enhanced the interaction between p97 and GluA1, while AC-YVAD-CMK treatment promoted the dissociation of p97 from the GluA1 complex and consequently facilitated the localization of GluA1 on the plasma membrane of cultured primary neurons. Finally, we reported that the deficits in motor function, learning and memory in animals with HIBD, were ameliorated by pharmacological intervention or genetic ablation of caspase-1.

CONCLUSION

Inhibiting the NLRP3 inflammasome signaling pathway promotes neurological recovery in animals with HIBD by increasing p97-mediated surface GluA1 expression, thereby providing new insight into HIE therapy.

GluA1 Degradation by Autophagy Contributes to Circadian Rhythm Effects on Cerebral Ischemia Injury

The mechanisms of many diseases, including central nervous system disorders, are regulated by circadian rhythms. The development of brain disorders such as depression, autism, and stroke is strongly associated with circadian cycles. Previous studies have shown that cerebral infarct volume is smaller at night (active phase) than during the day (inactive phase) in ischemic stroke rodent models. However, the underlying mechanisms remain unclear. Increasing evidence suggests that glutamate systems and autophagy play important roles in the pathogenesis of stroke. Here, we report that GluA1 expression was decreased and autophagic activity was increased in active-phase male mouse models of stroke compared with the inactive-phase models. In the active-phase model, induction of autophagy decreased the infarct volume, whereas inhibition of autophagy increased the infarct volume. Meanwhile, GluA1 expression was decreased following activation of autophagy and increased following inhibition of autophagy. We used Tat-GluA1 to uncouple p62, an autophagic adapter, from GluA1 and found that this blocked the degradation of GluA1, an effect similar to that of inhibition of autophagy in the active-phase model. We also demonstrated that knock-out of the circadian rhythm gene Per1 abolished the circadian rhythmicity of the volume of infarction and also abolished GluA1 expression and autophagic activity in wild-type (WT) mice. Our results suggest an underlying mechanism by which the circadian rhythm participates in the autophagy-dependent regulation of GluA1 expression, which influences the volume of infarction in stroke.SIGNIFICANCE STATEMENT Circadian rhythms affect the pathophysiological mechanisms of disease. Previous studies suggested that circadian rhythms affect the infarct volume in stroke, but the underlying mechanisms remain largely unknown. Here, we demonstrate that the smaller infarct volume after middle cerebral artery occlusion/reperfusion (MCAO/R) during the active phase is related to lower GluA1 expression and activation of autophagy. The decrease in GluA1 expression during the active phase is mediated by the p62-GluA1 interaction, followed by direct autophagic degradation. In short, GluA1 is the substrate of autophagic degradation, which mainly occurs after MCAO/R during the active phase but not the inactive phase.

An Electrophysiological and Proteomic Analysis of the Effects of the Superoxide Dismutase Mimetic, MnTMPyP, on Synaptic Signalling Post-Ischemia in Isolated Rat Hippocampal Slices

Metabolic stress and the increased production of reactive oxygen species (ROS) are two main contributors to neuronal damage and synaptic plasticity in acute ischemic stroke. The superoxide scavenger MnTMPyP has been previously reported to have a neuroprotective effect in organotypic hippocampal slices and to modulate synaptic transmission after in vitro hypoxia and oxygen-glucose deprivation (OGD). However, the mechanisms involved in the effect of this scavenger remain elusive. In this study, two concentrations of MnTMPyP were evaluated on synaptic transmission during ischemia and post-ischemic synaptic potentiation. The complex molecular changes supporting cellular adaptation to metabolic stress, and how these are modulated by MnTMPyP, were also investigated. Electrophysiological data showed that MnTMPyP causes a decrease in baseline synaptic transmission and impairment of synaptic potentiation. Proteomic analysis performed on MnTMPyP and hypoxia-treated tissue indicated an impairment in vesicular trafficking mechanisms, including reduced expression of Hsp90 and actin signalling. Alterations of vesicular trafficking may lead to reduced probability of neurotransmitter release and AMPA receptor activity, resulting in the observed modulatory effect of MnTMPyP. In OGD, protein enrichment analysis highlighted impairments in cell proliferation and differentiation, such as TGFβ1 and CDKN1B signalling, in addition to downregulation of mitochondrial dysfunction and an increased expression of CAMKII. Taken together, our results may indicate modulation of neuronal sensitivity to the ischemic insult, and a complex role for MnTMPyP in synaptic transmission and plasticity, potentially providing molecular insights into the mechanisms mediating the effects of MnTMPyP during ischemia.

Neurotoxic and cytoprotective mechanisms in the ischemic neocortex

Neuronal damage in ischemic stroke occurs due to permanent imbalance between the metabolic needs of the brain and the ability of the blood-vascular system to maintain glucose delivery and adequate gas exchange. Oxidative stress and excitotoxicity trigger complex processes of neuroinflammation, necrosis, and apoptosis of both neurons and glial cells. This review summarizes data on the structural and chemical changes in the neocortex and main cytoprotective effects induced by focal ischemic stroke. We focus on the expression of neurotrophins (NT) and molecular and cellular changes in neurovascular units in ischemic brain. We also discuss how these factors affect the apoptosis of cortical cells. Ischemic damage involves close interaction of a wide range of signaling molecules, each acting as an efficient marker of cell state in both the ischemic core and penumbra. NTs play the main regulatory role in brain tissue recovery after ischemic injury. Heterogeneous distribution of the BDNF, NT-3, and GDNF immunoreactivity is concordant with the selective response of different types of cortical neurons and glia to ischemic injury and allows mapping the position of viable neurons. Astrocytes are the central link in neurovascular coupling in ischemic brain by providing other cells with a wide range of vasotropic factors. The NT expression coincides with the distribution of reactive astrocytes, marking the boundaries of the penumbra. The development of ischemic stroke is accompanied by a dramatic change in the distribution of GDNF reactivity. In early ischemic period, it is mainly observed in cortical neurons, while in late one, the bulk of GDNF-positive cells are various types of glia, in particular, astrocytes. The proportion of GDNF-positive astrocytes increases gradually throughout the ischemic period. Some factors that exert cytoprotective effects in early ischemic period may display neurotoxic and pro-apoptotic effects later on. The number of apoptotic cells in the ischemic brain tissue correlates with the BDNF levels, corroborating its protective effects. Cytoprotection and neuroplasticity are two lines of brain protection and recovery after ischemic stroke. NTs can be considered an important link in these processes. To develop efficient pharmacological therapy for ischemic brain injury, we have to deepen our understanding of neurochemical adaptation of brain tissue to acute stroke.

Sevoflurane Preconditioning Downregulates GRIA1 Expression to Attenuate Cerebral Ischemia-Reperfusion-Induced Neuronal Injury

Cerebral ischemia/reperfusion (I/R) injury is the main cause of death following trauma. The neuroprotective effect of sevoflurane (Sev) has been implicated in cerebral I/R injury. However, the mechanisms remain elusive. In this study, we aimed to explore its function in PC12 exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) and in rats challenged with I/R. Sev pretreatment reduced the damage of PC12 cells after OGD/R treatment. Moreover, Sev pretreatment ameliorated neurobehavioral deficits induced by I/R treatment, reduced brain infarct volume, and decreased apoptosis of neurons in hippocampal tissues. Sev pretreatment reduced the surface expression of glutamate receptor 1 (GRIA1) in neurons, while GRIA1 reduced the neuroprotective effects of Sev pretreatment in vitro and in vivo. There was no difference in the surface expression of GRIA2 in rats with I/R and PC12 cells exposed to OGD/R. The ratio of GRIA1/GRIA2 surface expression was reduced, and calcium permeable-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (CP-AMPAR) was blocked by Sev. Together, Sev might exert beneficial effects on cerebral I/R-induced neuronal injury through inhibiting the surface expression of GRIA1 and blocking CP-AMPAR.

Endocytosis of AMPA receptors: Role in neurological conditions

AMPA receptors are glutamate-gated ion channels, present in a wide range of neuron types and in glial cells. Their main role is to mediate fast excitatory synaptic transmission, and therefore, they are critical for normal brain function. In neurons, AMPA receptors undergo constitutive and activity-dependent trafficking between the synaptic, extrasynaptic and intracellular pools. The kinetics of AMPA receptor trafficking is crucial for the precise functioning of both individual neurons and neural networks involved in information processing and learning. Many of the neurological diseases evoked by neurodevelopmental and neurodegenerative malfunctions or traumatic injuries are caused by impaired synaptic function in the central nervous system. For example, attention-deficit/hyperactivity disorder (ADHD), Alzheimer's disease (AD), tumors, seizures, ischemic strokes, and traumatic brain injury are all characterized by impaired glutamate homeostasis and associated neuronal death, typically caused by excitotoxicity. Given the important role of AMPA receptors in neuronal function, it is not surprising that perturbations in AMPA receptor trafficking are associated with these neurological disorders. In this book chapter, we will first introduce the structure, physiology and synthesis of AMPA receptors, followed by an in-depth description of the molecular mechanisms that control AMPA receptor endocytosis and surface levels under basal conditions or synaptic plasticity. Finally, we will discuss how impairments in AMPA receptor trafficking, particularly endocytosis, contribute to the pathophysiology of various neurological disorders and what efforts are being made to therapeutically target this process.

Acidosis in arterial blood gas testing is associated with clinical outcomes after endovascular thrombectomy

Background

Despite recanalization, some of the patients undergoing endovascular thrombectomy (EVT) still suffer from unfavorable outcomes. Patients with poor prognoses are often accompanied by acidosis in arterial blood gas (ABG) testing. We, therefore, explored the ABG testing results in the early phase of recanalization and analyzed their association with poor prognosis.

Patients and methods

We identified all patients with ischemic stroke and successful endovascular recanalization for anterior circulation vessel occlusion between June 2019 and May 2022. ABG testing was performed in all patients within 0-30 min and 8 h after endovascular therapy. We investigated the relationship between the ABG testing results with symptomatic intracerebral hemorrhage (sICH), hemicraniectomy, and mortality.

Results

A total of 123 patients with stroke after endovascular thrombectomy were analyzed. Of those, eight (6.5%) patients had postinterventional sICH. Acidosis was associated with sICH. Decreased HCO 3 - levels and HCO 3 - levels at 8 h after EVT were independently related to a higher risk of sICH. Twelve (9.8%) patients underwent hemicraniectomy for postischemic malignant edema and similar results were found for hemicraniectomy. Increased lactate at 8 h after EVT and decreased HCO 3 - levels at 8 h after EVT were closely associated with hemicraniectomy. Twenty-two (17.9%) patients died within 3 months. Decreased HCO 3 - levels were independently related to mortality, as were decreased pH levels at 8 h after EVT and decreased HCO 3 - levels at 8 h after EVT.

Conclusion

Acidosis is associated with clinical outcomes after endovascular therapy and may help to select patients with poor prognosis in the acute early phase of recanalization.

Altered methylation pattern in EXOC4 is associated with stroke outcome: an epigenome-wide association study

BACKGROUND AND PURPOSE

The neurological course after stroke is highly variable and is determined by demographic, clinical and genetic factors. However, other heritable factors such as epigenetic DNA methylation could play a role in neurological changes after stroke.

METHODS

We performed a three-stage epigenome-wide association study to evaluate DNA methylation associated with the difference between the National Institutes of Health Stroke Scale (NIHSS) at baseline and at discharge (ΔNIHSS) in ischaemic stroke patients. DNA methylation data in the Discovery (n = 643) and Replication (n = 62) Cohorts were interrogated with the 450 K and EPIC BeadChip. Nominal CpG sites from the Discovery (p value < 10-06) were also evaluated in a meta-analysis of the Discovery and Replication cohorts, using a random-fixed effect model. Metabolic pathway enrichment was calculated with methylGSA. We integrated the methylation data with 1305 plasma protein expression levels measured by SOMAscan in 46 subjects and measured RNA expression with RT-PCR in a subgroup of 13 subjects. Specific cell-type methylation was assessed using EpiDISH.

RESULTS

The meta-analysis revealed an epigenome-wide significant association in EXOC4 (p value = 8.4 × 10-08) and in MERTK (p value = 1.56 × 10-07). Only the methylation in EXOC4 was also associated in the Discovery and in the Replication Cohorts (p value = 1.14 × 10-06 and p value = 1.3 × 10-02, respectively). EXOC4 methylation negatively correlated with the long-term outcome (coefficient = - 4.91) and showed a tendency towards a decrease in EXOC4 expression (rho = - 0.469, p value = 0.091). Pathway enrichment from the meta-analysis revealed significant associations related to the endocytosis and deubiquitination processes. Seventy-nine plasma proteins were differentially expressed in association with EXOC4 methylation. Pathway analysis of these proteins showed an enrichment in natural killer (NK) cell activation. The cell-type methylation analysis in blood also revealed a differential methylation in NK cells.

CONCLUSIONS

DNA methylation of EXOC4 is associated with a worse neurological course after stroke. The results indicate a potential modulation of pathways involving endocytosis and NK cells regulation.

Association of Oxidative Stress with Neurological Disorders

BACKGORUND

Oxidative stress is one of the main contributing factors involved in cerebral biochemical impairment. The higher susceptibility of the central nervous system to reactive oxygen species mediated damage could be attributed to several factors. For example, neurons use a greater quantity of oxygen, many parts of the brain have higher concentraton of iron, and neuronal mitochondria produce huge content of hydrogen peroxide. In addition, neuronal membranes have polyunsaturated fatty acids, which are predominantly vulnerable to oxidative stress (OS). OS is the imbalance between reactive oxygen species generation and cellular antioxidant potential. This may lead to various pathological conditions and diseases, especially neurodegenerative diseases such as, Parkinson's, Alzheimer's, and Huntington's diseases.

OBJECTIVES

In this study, we explored the involvement of OS in neurodegenerative diseases.

METHODS

We used different search terms like "oxidative stress and neurological disorders" "free radicals and neurodegenerative disorders" "oxidative stress, free radicals, and neurological disorders" and "association of oxidative stress with the name of disorders taken from the list of neurological disorders. We tried to summarize the source, biological effects, and physiologic functions of ROS.

RESULTS

Finally, it was noted that more than 190 neurological disorders are associated with oxidative stress.

CONCLUSION

More elaborated studies in the future will certainly help in understanding the exact mechanism involved in neurological diseases and provide insight into revelation of therapeutic targets.

Ginkgo biloba extracts inhibit post-ischemic LTP through attenuating EPSCs in rat hippocampus

Ginkgo biloba extract 761 (EGb761), a standardized extract from the Ginkgo biloba leaf, is purported to inhibit NMDA receptor-mediated neuronal excitotoxicity and protect neurons form ischemic injury. However, the specific signal pathway involved in the effects of EGb761 on synaptic plasticity is still in dispute. In this article, effects of EGb761 and its monomer component ginkgolide A (GA), ginkgolide B (GB), ginkgolide C (GC) and quercetin on rat hippocampal synaptic plasticity were studied. The evoked Excitatory postsynaptic currents (EPSCs) and miniature EPSCs were recorded on hippocampal slices from SD rats (14-21 days of age) by whole-cell patch-clamp recording and long-term potentiation (LTP) was induced by theta-burst stimulation. Acutely applied EGb761 inhibited the LTP, but bilaterally affect the evoked EPSCs. The evoked EPSCs were increased by incubation of lower concentration of EGb761, then the evoked EPSCs were decreased by incubation of higher concentration of EGb761. EGb761 monomer component GA, GB and GC could also inhibit the TBS-induced LTP and EPSC amplitude but not paired-pulse ratio (PPR). But quercetin, another monomer component of EGb761, led to increase in EPSC amplitude and decrease in PPR. Simultaneously, EGb761 and its monomer component ginkgolides inhibited the post-ischemic LTP (i-LTP) by inhibiting the EPSCs and the AMPA receptor subunit GluA1 expression on postsynaptic membrane. The results indicated that high concentration of EGb761 might inhibit LTP and i-LTP through inhibition effects of GA, GB and GC on AMPA receptors.