Neurotoxic Injury Research Articles

Design, Synthesis, and Biological Evaluation of Novel Cinnamide Derivatives as Neuroprotective Agents for the Treatment of Cerebral Ischemia.

Ischemic stroke, the most common type of cerebrovascular accident, is a major cause of severe disability among adults worldwide. Although there has been progress in interventions for ischemic stroke in the past decades, there is no effective treatment to prevent brain damage in acute ischemic stroke. Therefore, it is urgent to develop novel neuroprotective agents with a wide therapeutic time window to provide a better prognosis for ischemic stroke patients. The current study aimed to synthesize novel derivatives with substituent cinnamide scaffolds, evaluate biological activity, and obtain neuroprotective agents. The target compounds were synthesized using classical methods of medicinal chemistry. The neuroprotective effects in vitro against Glu-induced neurotoxicity injury were evaluated in PC12 cells by MTT assay. The cell apoptosis was analyzed by flow cytometer. The proteins were detected by western blotting. The neuroprotective activities in vivo were determined in two in vivo models of global and focal cerebral ischemia. Among the title compounds, 9t, 9u, 9y, and 9z exhibited good neuroprotection in vivo and in vitro, which were selected and further studied to determine their mechanism of action. 9t, 9u, 9y and 9z protected PC12 cells against glutamate-induced apoptosis in a dose-dependent manner via caspase-3 pathway. Moreover, the four compounds significantly reduced brain infarct area and exhibited excellent neuroprotective activities in the in vivo MCAO model. Compounds 9t, 9u, 9y, and 9z, as potent neuroprotective agents with anti- neurotoxicity activity in vitro and anticerebral infarction efficacy in vivo, might serve as a useful molecular tool for further physiology and pathophysiology function studies, leading to potential clinical therapeutic agents for ischemic injury.

Melatonin attenuates sevoflurane-induced hippocampal damage and cognitive deficits in neonatal mice by suppressing CypD in parvalbumin neurons

BackgroundSevoflurane, a commonly administered inhaled anesthetic, is found to induce synaptic and mitochondrial damage in neonatal mice. Mitochondrial membrane potential (MMP) changes, mediated by Cyclophilin D (CypD), are implicated in mitochondrial function. Melatonin, known for its significant neuroprotective properties, was investigated in this study to elucidate its mechanisms in mitigating the cognitive impairment caused by sevoflurane. MethodsThe mice were categorized into several groups, including the control, vehicle, sevoflurane, vehicle plus sevoflurane, and melatonin plus sevoflurane groups. From postnatal day 6 to day 8, the mice were administered inhaled sevoflurane or intraperitoneal melatonin. MMP and reactive oxygen species (ROS) were measured using appropriate detection kits. The protein expression levels of PSD95, Synapsin Ⅰ, and CypD in the hippocampus were analyzed through western blotting in acute and prolonged terms. Immunofluorescence staining was used to assess the co-localizations of PSD95 or CypD in parvalbumin (PV) neurons. Cognitive ability was evaluated through novel object recognition, social interaction experiment, and the Morris water maze. ResultsThe findings revealed that repeated exposure to sevoflurane in neonatal mice resulted in cognitive and synaptic impairment. Furthermore, melatonin administration suppressed the ROS and CypD protein expression, enhanced the MMP in mitochondria and synaptic protein expression in PV neurons, and ameliorated cognitive deficits. ConclusionMelatonin alleviated sevoflurane-induced cognitive deficits by suppressing CypD and promoting synaptic development in hippocampal PV neurons. These results provide valuable insights into a promising therapeutic approach for preventing neurotoxic injuries caused by general anesthetics.

Banxia-Houpu decoction inhibits iron overload and chronic intermittent hypoxia-induced neuroinflammation in mice

Ethnopharmacological relevanceThe Banxia-Houpu decoction (BHD), a renowned prescription documented in the Chinese medical book “The Synopsis of the Golden Chamber,” has been proven to effectively mitigate inflammation within the central nervous system. Previous studies have demonstrated the efficacy of BHD in ameliorating symptoms in patients with obstructive sleep apnea (OSA). Nevertheless, the precise mechanisms and comprehensive effects of BHD on central system injury in OSA models have not been fully investigated. Aim of the studyTo investigate whether BHD could inhibit neuroinflammation to decrease iron-induced neurotoxic injury in CIH mice. Materials and methodsC57BL/6N mice were divided into the Con, CIH, and BHD groups. Mice were exposed to CIH (21%–5% FiO2, 3 min/cycle, 8 h/d), and BHD was administered by gavage (3.51, 7.01, and 14.02 g/kg). The polarization of microglia, inflammatory factors, hepcidin, and brain iron levels were determined. ResultsThe administration of BHD at a dosage of 7.01 g/kg demonstrated a significant reduction in neurobehavioral abnormalities, neuronal damage, and degeneration caused by CIH. BHD exhibited the ability to inhibit the transition of microglial polarization from M2 to M1 by upregulating CD163 expression and downregulating iNOS levels. Furthermore, BHD decreased pro-inflammatory factor levels and increased anti-inflammatory factor levels. Additionally, BHD was found to decrease hepcidin expression in astrocytes through the TLR4/MyD88/NF-κB signaling pathway. BHD reduced the total and neuronal iron levels by elevating FPN1 and reducing TfR1 levels. BHD exhibited positive effects on synapse and synaptic spine abnormalities, as well as an increase in the Bcl-2/Bax ratio, thereby mitigating neuronal damage induced by CIH. ConclusionsBased on these findings, BHD holds potential as a therapeutic intervention for neural damage injuries, which offers a theoretical foundation for the treatment of patients with OSA in clinical.

Establishment of an animal model of sciatic nerve injury induced by local anesthetics.

Peripheral neurotoxicity injury caused by local anesthetics is a common complication of clinical anesthesia. The study of its mechanism is helpful to prevent and treat the neurotoxic injury of local anesthetics. Previous studies on peripheral neurotoxicity injury caused by local anesthetics have mainly focused on in vitro cell experiments. Due to the lack of an animal model of peripheral neurotoxicity damage caused by local anesthetics, there are few in vivo experimental studies regarding this topic. Herein, 1% ropivacaine hydrochloride was injected into the sciatic nerve by direct incision and exposure of the sciatic nerve to create a local anesthetic neurotoxic injury model. The results showed that 1% ropivacaine hydrochloride could reduce the lower limb motor score and mechanical paw withdrawal threshold in mice 48hours after injection. Pathological sections showed that 48hours after treatment with 1% ropivacaine hydrochloride, the sciatic nerve showed increased axonal edema and degeneration, edema between nerve fiber bundles, increased degeneration of axon and myelin sheath vacuoles, edema of nerve bundle membrane and local degeneration and necrosis, and a large number of inflammatory cells around the nerve adventitia were soaked. The above results show that under open vision, 1% ropivacaine hydrochloride can cause injury to the sciatic nerve after 48h of treatment, which can simulate the neurotoxic damage of local anesthetics. This animal model provides a research tool for studying the mechanism of neurotoxic injury caused by local anesthetics.

A structural spectroscopic study of dissociative anaesthetic methoxphenidine

Methoxphenidine was originally patented for its properties to treat neurotoxic injury.

Neurotoxicity induced by the pyrethroid lambda-cyhalothrin: Alterations in monoaminergic systems and dopaminergic and serotoninergic pathways in the rat brain.

The effects of Type II pyrethroid lambda-cyhalothrin on dopamine (DA) and serotonin (5-HT) synthesis in rat brain regions (striatum, hippocampus, prefrontal cortex, hypothalamus and midbrain) were studied. Lambda-cyhalothrin (1, 4 and 8mg/kg bw, oral gavage, 6 days) induced a decrease of DA, 5-HT and metabolites contents, in a brain regional- and dose-related manner. The major decreases in DA and 5-HT contents were observed in hippocampus and prefrontal cortex tissues. This research study also showed in hippocampus and prefrontal cortex, that lambda-cyhalothrin modified the mRNA levels of DA transporter gene (Dat1 up-regulation), 5-HT transporter gene (SERT down-regulation), DA receptor genes (Drd1and Drd2 down-regulation), 5-HT receptor genes (5-HT1A and 5-HT2A down-regulation/up-regulation), DA synthesis gene (TH down-regulation), 5-HT synthesis gene (TPH2 down-regulation), DA and 5-HT degradation genes (MAOA and MAOB up-regulation). These results reveal that lambda-cyhalothrin altered central nervous system (CNS) monoaminergic neurotransmitters. Lambda-cyhalothrin evoked a selective neurotoxic injury to dopaminergic and serotoninergic pathways. These findings may clarify on the pyrethroids-induced neurotoxicity mechanisms and could involve pyrethroids as environmental risk factors leading to the development of neurodegenerative diseases.

An adult-stage transcriptional program for survival of serotonergic connectivity.

SUMMARYNeurons must function for decades of life, but how these non-dividing cells are preserved is poorly understood. Using mouse serotonin (5-HT) neurons as a model, we report an adult-stage transcriptional program specialized to ensure the preservation of neuronal connectivity. We uncover a switch in Lmx1b and Pet1 transcription factor function from controlling embryonic axonal growth to sustaining a transcriptomic signature of 5-HT connectivity comprising functionally diverse synaptic and axonal genes. Adult-stage deficiency of Lmx1b and Pet1 causes slowly progressing degeneration of 5-HT synapses and axons, increased susceptibility of 5-HT axons to neurotoxic injury, and abnormal stress responses. Axon degeneration occurs in a die back pattern and is accompanied by accumulation of α-synuclein and amyloid precursor protein in spheroids and mitochondrial fragmentation without cell body loss. Our findings suggest that neuronal connectivity is transcriptionally protected by maintenance of connectivity transcriptomes; progressive decay of such transcriptomes may contribute to age-related diseases of brain circuitry.

Long-Term Cognitive Dysfunction in Cancer Survivors.

Cancer-related cognitive impairment (CRCI) is a frequent side effect experienced by an increasing number of cancer survivors with a significant impact on their quality of life. Different definitions and means of evaluation have been used in available literature; hence the exact incidence of CRCI remains unknown. CRCI can be described as cognitive symptoms reported by cancer patients in self-reported questionnaires or as cognitive changes evaluated by formal neuropsychological tests. Nevertheless, association between cognitive symptoms and objectively assessed cognitive changes is relatively weak or absent. Studies have focused especially on breast cancer patients, but CRCI has been reported in multiple types of cancer, including colorectal, lung, ovarian, prostate, testicular cancer and hematological malignancies. While CRCI has been associated with various treatment modalities, including radiotherapy, chemotherapy, hormone therapy and novel systemic therapies, it has been also detected prior to cancer treatment. Therefore, the effects of cancer itself with or without the psychological distress may be involved in the pathogenesis of CRCI as a result of altered coping mechanisms after cancer diagnosis. The development of CRCI is probably multifactorial and the exact mechanisms are currently not completely understood. Possible risk factors include administered treatment, genetic predisposition, age and psychological factors such as anxiety, depression or fatigue. Multiple mechanisms are suggested to be responsible for CRCI, including direct neurotoxic injury of systemic treatment and radiation while other indirect contributing mechanisms are hypothesized. Chronic neuroinflammation mediated by active innate immune system, DNA-damage or endothelial dysfunction is hypothesized to be a central mechanism of CRCI pathogenesis. There is increasing evidence of potential plasma (e.g., damage associated molecular patterns, inflammatory components, circulating microRNAs, exosomes, short-chain fatty acids, and others), cerebrospinal fluid and radiological biomarkers of cognitive dysfunction in cancer patients. Discovery of biomarkers of cognitive impairment is crucial for early identification of cancer patients at increased risk for the development of CRCI or development of treatment strategies to lower the burden of CRCI on long-term quality of life. This review summarizes current literature on CRCI with a focus on long-term effects of different cancer treatments, possible risk factors, mechanisms and promising biomarkers.

Sarm1 haploinsufficiency or low expression levels after antisense oligonucleotides delay programmed axon degeneration.

SummaryActivation of the pro-degenerative protein SARM1 after diverse physical and disease-relevant injuries causes programmed axon degeneration. Original studies indicate that substantially decreased SARM1 levels are required for neuroprotection. However, we demonstrate, in Sarm1 haploinsufficient mice, that lowering SARM1 levels by 50% delays programmed axon degeneration in vivo after sciatic nerve transection and partially prevents neurite outgrowth defects in mice lacking the pro-survival factor NMNAT2. In vitro, the rate of degeneration in response to traumatic, neurotoxic, and genetic triggers of SARM1 activation is also slowed. Finally, we demonstrate that Sarm1 antisense oligonucleotides decrease SARM1 levels by more than 50% in vitro, which delays or prevents programmed axon degeneration. Combining Sarm1 haploinsufficiency with antisense oligonucleotides further decreases SARM1 levels and prolongs protection after neurotoxic injury. These data demonstrate that axon protection occurs in a Sarm1 gene dose-responsive manner and that SARM1-lowering agents have therapeutic potential, making Sarm1-targeting antisense oligonucleotides a promising therapeutic strategy.

Neuroprotective effects of dopamine D2 receptor agonist on neuroinflammatory injury in olfactory bulb neurons in vitro and in vivo in a mouse model of allergic rhinitis

Available evidence indicates that dopamine D2 receptor modulates the neurotoxic effects induced by glutamate. However, neurotoxicity mediated by AMPA-subtype glutamate receptor has rarely been studied in the olfactory bulb. This study mainly explores the neuroprotective effects of dopamine D2 receptor agonist on AMPA receptor-mediated neurotoxicity in the olfactory bulb in a mouse model of allergic rhinitis (AR) with olfactory dysfunction (OD). In our study, we found that AR with OD was closely associated with increased surface expression of the AMPA receptor GluR1, reduced surface expression of GluR2, and apoptosis damage in the olfactory bulb in vivo. Quinpirole (a dopamine D2 receptor agonist) improved olfactory function in mice, ameliorated apoptosis injury in the olfactory bulb but not in the olfactory mucosa, and inhibited the internalization of GluR2-containing AMPA receptor in vitro and in vivo. In addition, phosphorylation plays a crucial role in the regulation of AMPA receptor trafficking. Our results showed that quinpirole reduced the phosphorylation of GluR1 S845 and GluR2 S880 in olfactory bulb neurons in vitro, but it had no obvious effect on GluR1 S831. Therefore, dopamine D2 receptor agonist may inhibit the phosphorylation of GluR1 S845 and GluR2 S880, thereby reducing AMPA receptor-mediated neurotoxicity and alleviating neurotoxic injury to the olfactory bulb caused by AR.

MiR-29a and the PTEN–GSK3β axis are involved in aluminum-induced damage to primary hippocampal neuronal networks

We previously reported that aluminum (Al) can cause a range of neurotoxic injuries including progressive irreversible synaptic structural damage and synaptic dysfunction, and eventually neuronal deaths. Mechanism of Al-induced electrophysiological and neuronal connectivity changes in neurons may indicate damage to the neuronal network. Here, mouse primary hippocampal neurons were cultured on micro-electrode array (MEA)- and high-content analysis (HCA)-related plates, showing that Al exposure significantly inhibited hippocampal neuronal electrical spike activity and neurite outgrowth characterized by a reduction in neurite branching and a decrease in the average total neurite length in relation to both Al dose and time of incubation. In recent years, miR-29a/ phosphatase and tensin homolog (PTEN) have been found to play pivotal roles in the morphogenesis of neurons, it has been confirmed in vitro and in vivo that the PTEN–Glycogen synthase kinase-3β (GSK-3β) axis regulates neurite outgrowth. The present study demonstrated that increases in Al exposure and dose gradually reduce miR-29a expression. Up-regulation of miR-29a in the hippocampal neurons by lentivirus transfection reversed the decrease in electrical spike activity and the reduction in both neurite branching and length induced by Al. Moreover, miR-29a suppressed the expression of PTEN and increased the level of phosphorylated Protein Kinase B (p-AKT) and p-GSK-3β which were inhibited by the Al treatment. This suggests that miR-29a is critically involved in the functional and structural neuronal damage induced by Al and is a potential target for Al neurotoxicity. Moreover, the reduction of neurite length and branching induced by Al exposure was regulated by miR-29a and its target neuronal PTEN–GSK3β signaling pathway, which also represents a possible mechanism of Al-induced the inhibition of the electrical activity. Collectively, Al-induced damage to the neuronal network occurred through miR-29a-mediated alterations of the PTEN–GSK3β signaling pathway.

Edaravone attenuates H2O2 or glutamate-induced toxicity in hippocampal neurons and improves AlCl3/D-galactose induced cognitive impairment in mice

Edaravone (Eda) is a free radical scavenger used in clinical trials for the treatment of ischemic stroke and amyotrophic lateral sclerosis. However, how Eda exerts its neuroprotective effects remains to be elucidated. We investigated the neuroprotective effects of Eda in cultured hippocampal neurons and in a mouse model of AlCl3/D-galactose-induced cognitive impairment. Eda protected hippocampal neurons by eliminating H2O2 or glutamate-induced toxicity, leading to decreased cell viability and neurite shortening. Consistently, Eda restored impaired levels of BDNF, FGF2 and their associated signaling axes (including TrkB, p-Akt and Bcl-2) to attenuate neuronal death. In a mouse model of chemically-induced cognitive impairment, Eda restored the levels of BDNF, FGF2 and TrkB/Akt signaling axis to attenuate neuronal apoptosis, thereby ameliorating cognitive impairment. Meanwhile, the pro-inflammation was eliminated due to the restoration of pro-inflammatory factors such as TNF-α, IL-6, IL-1β, and NOS2. In summary, Eda is an effective drug for protecting neurons from neurotoxic injury. BDNF, FGF2, and their regulated pathways may be potential therapeutic targets for neuroprotection.

Dichlorvos poisoning caused chicken cerebrum tissue damage and related apoptosis-related gene changes

Dichlorvos (DDVP) is an organophosphorus compound with insecticidal effects. Organophosphorus pesticides can easily enter humans or animals through various channels, causing cerebrum nerve cell damage. The purpose of this research was to investigate whether acute dichlorvos poisoning can cause cerebrum neurotoxic injury and change the expression of apoptosis-related genes in broilers, further clarify the neurotoxic mechanism after acute dichlorvos exposure, and provide a research basis for prevention, treatment and gene drug screening in the later stage. In this experiment, healthy yellow-feathered broilers were randomly assigned to the control group, the low-dose group (1.13 mg/kg) and the high-dose group (10.2 mg/kg) for modelling observation, and detection was conducted based on H&E (haematoxylin and eosin) staining, transmission electron microscopy analysis of tissue sections, immunofluorescence techniques and real-time quantitative polymerase chain reaction (qRT-PCR). The results showed that organophosphorus poisoning was accompanied by obvious neurological symptoms such as limb twitching and massive salivation. In addition, we observed that compared with the control group, the number of lysed nuclear neurons, deformed vascular sheaths, and glial cells and the expression of glial fibrillary acidic protein (GFAP) in the poisoned group of broilers increased significantly, and the increase was more obvious in the low-dose group. However, cell apoptosis and mitochondrial structure dissolution were most pronounced in the high-dose group. Moreover, the qRT-PCR results also revealed significant changes in the expression of apoptosis-related genes. The expression levels of ACC, LKB1 and GPAT increased significantly, while the expression of HMGR, PPARα, CPT1 and AMPKα1 decreased significantly. In summary, these results indicated that dichlorvos may cause the lysis of cerebrum nerve cell nuclei, completely destroy the structure of mitochondria, change the expression of related apoptotic genes, enhance cell apoptosis, and cause neurogenic damage to the cerebrum. These research results offer a theoretical foundation for the prevention and treatment of acute organophosphate toxicosis.

<i>Sarm1</i> Haploinsufficiency and Low Expression Levels after Antisense Oligonucleotides Delays Programmed Axon Degeneration

Activation of pro-degenerative protein SARM1 in response to diverse physical and disease-relevant injuries causes programmed axon degeneration. Original studies indicated substantially decreased levels of SARM1 were required for neuroprotection. However, we demonstrate that lowering SARM1 levels by 50% in Sarm1 haploinsufficient mice delays programmed axon degeneration in vivo, after sciatic nerve transection, in vitro in response to diverse traumatic, neurotoxic, and genetic triggers of SARM1 activation, and partially prevents neurite outgrowth defects in mice lacking pro-survival factor NMNAT2. We also demonstrate the capacity for Sarm1 antisense oligonucleotides to decrease SARM1 levels by more than 50% which delays or prevents programmed axon degeneration in vitro. Combining Sarm1 haploinsufficiency with antisense oligonucleotides further decreases SARM1 levels and prolongs protection after neurotoxic injury. These data demonstrate that axon protection occurs in a Sarm1 gene-dose responsive manner and that SARM1 lowering agents have therapeutic potential. Thus, antisense oligonucleotide targeting of Sarm1 is a promising therapeutic strategy.

Changes in the expression of endothelial monocyte‑activating polypeptide II in the rat hippocampus following status epilepticus.

Endothelial monocyte-activating polypeptide II (EMAP II) is a sensitive marker of neurotoxic injury, the expression of which increases significantly under conditions of stress, such as hypoxia or apoptosis. Studies have confirmed the extensive apoptosis of nerve cells in the brain following status epilepticus (SE), and the occurrence of SE can confer a hypoxic state on cells. The purpose of the present study was to observe the changes in the expression of EMAP II, and in the numbers and tight junction protein levels of micro-vascular endothelial cells in the hippocampus of rats with pilocarpine-induced SE. The protein expression levels of EMAP II, CD31, zonula occludens 1 (ZO-1) and occludin in the hippocampus were determined by immunofluorescence and western blot analyses. It was found that almost 75.6% of the rats in the SE group developed Racine stage IV-V seizures at approximately 44.7±18.8 min after the pilocarpine administration, and the 24-h mortality rate was almost 10.4%. The weight of the rats in the SE group was significantly decreased within 24 h following SE. Immunofluorescence staining revealed a low EMAP II expression in the hippo-campus of the rats in the control group; however, the numbers of EMAP II-positive cells were significantly increased in the SE group from 2 h to 21 days. The trend of EMAP II protein expression was consistent with that obtained with immunofluorescence staining. The numbers of CD31-positive microvascular endothelial cells were significantly increased from 24 h to 21 days compared with the levels in the control group. The protein expression of ZO-1 and occludin was most significantly decreased in the SE group. On the whole, the present study demonstrated that the expression of EMAP II in the rat hippocampus was upregulated in the SE model, which may promote angiogenesis and alter the TJ integrity of brain microvascular endothelial cells, with an increased number of CD31-positive microvascular endothelial cells and a decreased expression of ZO-1 and occludin.

Research progress of ferroptosis-related mechanism and diseases

Ferroptosis is a new programmed cell death characterized by iron dependent and intracellular oxidative accumulation. Current studies have confirmed that ferroptosis is involved in the occurrence and development of neurotoxicity injury, tumors, cardiovascular diseases and other diseases. This paper reviews the mechanisms of ferroptosis and its role in related diseases based on recent studies.

Mechanistic study of mtROS-JNK-SOD2 signaling in bupivacaine-induced neuron oxidative stress.

Manganese superoxide dismutase (SOD2) is a key enzyme to scavenge free radical superoxide in the mitochondrion. SOD2 deficiency leads to oxidative injury in cells. Bupivacaine, a local anesthetic commonly used in clinic, could induce neurotoxic injury via oxidative stress. The role and the mechanism of SOD2 regulation in bupivacaine-induced oxidative stress remains unclear. Here, bupivacaine was used to treat Sprague-Dawley rats with intrathecal injection and culture human neuroblastoma cells for developing vivo injury model and vitro injury model. The results showed that bupivacaine caused the over-production of mitochondrial reactive oxygen species (mtROS), the activation of C-Jun N-terminal kinase (JNK), and the elevation of SOD2 transcription. Decrease of mtROS with N-acetyl-L-cysteine attenuated the activation of JNK and the increase of SOD2 transcription. Inhibition of JNK signaling with a small interfering RNA (siRNA) or with sp600125 down-regulated the increase of SOD2 transcription. SOD2 gene knock-down exacerbated bupivacaine-induced mtROS generation and neurotoxic injury but had no effect on JNK phosphorylation. Mito-TEMPO (a mitochondria-targeted antioxidant) could protect neuron against bupivacaine-induced toxic injury. Collectively, our results confirm that mtROS stimulates the transcription of SOD2 via activating JNK signaling in bupivacaine-induced oxidative stress. Enhancing antioxidant ability of SOD2 might be crucial in combating bupivacaine-induced neurotoxic injury.

The mechanism of CaMK2α-MCU-mitochondrial oxidative stress in bupivacaine-induced neurotoxicity

Ca2+/calmodulin dependent protein kinase2α (CaMK2α) is a serine/threonine protein kinase in neurons and leads to neuronal injury when it is activated abnormally. Bupivacaine, a local anesthetic commonly used in regional nerve block, could induce neurotoxicity via apoptotic injury. Whether or not CaMK2α is involved in bupivacaine-induced neurotoxicity and it is regulated remains unclear. In this study, bupivacaine was administered for intrathecal injection in C57BL/6 mice for building vivo injury model and was used to culture human neuroblastoma (SH-SY5Y) cells for building vitro injury model. The results showed that bupivacaine induced mitochondrial oxidative stress and neurons apoptotic injury, promoted phosphorylation of CaMK2α and cAMP-response element binding protein (CREB), and elevated mitochondrial Ca2+ uniporter (MCU) expression. Furthermore, it induced CaMK2α phosphorylation at Thr286 which phosphorylated CREB at Ser133 and up-regulated MCU transcriptional expression. Inhibition of CaMK2α-MCU signaling with knock-down of CaMK2α and MCU or with inhibitors (KN93 and Ru360) significantly mitigated bupivacaine-induced neurotoxic injury. Over-expression of CaMK2α significantly enhanced above oxidative injury. Activated MCU with agonist (spermine) reversed protective effect of siCaMK2α on bupivacaine-induced mitochondrial oxidative stress. Our data revealed that CaMK2α-MCU-mitochondrial oxidative stress pathway is a major mechanism whereby bupivacaine induces neurotoxicity and inhibition of above signaling could be a therapeutic strategy in the treatment of bupivacaine-induced neurotoxicity.

NLRP3 inflammasome inhibition attenuates subacute neurotoxicity induced by acrylamide in vitro and in vivo

Acrylamide (AA) constitutes an important industrial chemical agent and well-known neurotoxin. However, the mechanism underlying AA-mediated neurotoxicity is extremely complicated and controversial. In this study, we found that activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome and its subsequent downstream inflammatory responses plays an important role in AA-induced neurotoxicity mechanisms. In vitro experiments revealed that AA (2.5 mM) induced BV2 microglial cytotoxicity and triggered NLRP3 inflammasome activation along with downstream proinflammatory cytokine interleukin-1β and interleukin-18 expression. Treatment with inhibitor or NLRP3 siRNA efficiently protected BV2 microglial cells against AA-induced cytotoxicity and reversed NLRP3 inflammasome activation and its mediated inflammatory reaction. Similarly, AA exposure (50 mg/kg) for 10 consecutive days caused significant activation of NLRP3 inflammasomes and neuroinflammation in C57BL/6 mice, whereas inhibiting these effects through specific NLRP3 inflammasome blocker MCC950 (5 mg/kg) intervention or NLRP3 knock-out significantly ameliorated AA-induced ataxia, cerebellar Purkinje cells degeneration, and apoptosis. Furthermore, we demonstrated that antagonism of NLRP3 could also up-regulate the Nrf2 signalling pathway and related antioxidant genes. In conclusion, our findings indicate that activation of the NLRP3 inflammasome pathway is involved in AA-induced neurotoxicity, whereas MCC950 treatment or NLRP3 knock-out could effectively protect against AA-induced neurotoxic injury through the inhibition of neuroinflammation and activation of the Nrf2 antioxidant pathway. Therefore, the NLRP3 inflammasome might serve as a promising therapeutic target, with drugs designed to specifically inhibit this pathway potentially providing new avenues for preventing or ameliorating AA poisoning.

Astrocyte activation following nitrous oxide exposure is related to oxidative stress and glutamate excitotoxicity

Background and AimsNitrous oxide is commonly used as an anesthetic agent and its exposure produces prolonged inactivation of vitamin B12. Nitrous oxide toxicity is associated with central nervous system changes which are similar to sub-acute combined degeneration (SACD). Astrocytes have important role in neurotoxic injuries, but have not been evaluated in N2O toxicity. In the present study, we have evaluated the changes in astrocytes in N2O exposed rats and correlated with neurobehavioral changes, oxidative stress and glutamate level. Material and MethodsAdult wistar male rats were exposed to N2O oxygen mixture in 1:1 ratio at a rate of 2 L/min for 120 min for 60 days. Control rats underwent similar exposure to oxygen. At the end of exposure, spontaneous locomotor activities (total distance travelled, time resting, time moving, number of rearing, stereotypic count) and grip strength were evaluated. Plasma glutathione (GSH), total antioxidant capacity (TAC), serum malonodialdehyde (MDA) and serum homocysteine (Hcy) were measured by spectrophotometer. Glutamate in the cerebral cortex and cerebellum were measured by colorimetry. Immunohistochemistry for astrocyte (GFAP) phenotypic analysis and its activation in brain and spinal cord were measured using image J software in N2O exposed and control rats. ResultsThe N2O exposed rats had significant reduction in total distance travelled, time moving and number of rearing whereas time resting increased compared to the control rats. Hcy, glutamate and MDA levels were significantly increased, however GSH and TAC level decreased in N2O exposed group compared to the controls. Astrocyte phenotype and its activation was significantly altered more so in spinal cord compared to cerebral cortex and was associated with neurobehavioral changes, oxidative stress and glutamate level. ConclusionsN2O related clinical dysfunction may be related to changes in astrocyte activation which is related to oxidative stress and glutamate neurotoxicity.