Neuronal Cell Loss Research Articles

Vulnerability of neurofilament-expressing neurons in frontotemporal dementia

Frontotemporal dementia (FTD) is an umbrella term for several early onset dementias, that are caused by frontotemporal lobar degeneration (FTLD), which involves the atrophy of the frontal and temporal lobes of the brain. Neuron loss in the frontal and temporal lobes is a characteristic feature of FTLD, however the selective vulnerability of different neuronal populations in this group of diseases is not fully understood. Neurofilament-expressing neurons have been shown to be selectively vulnerable in other neurodegenerative diseases, including Alzheimer's disease and amyotrophic lateral sclerosis, therefore we sought to investigate whether this neuronal population is vulnerable in FTLD. We also examined whether neuronal sub-type vulnerability differed between FTLD with TDP-43 inclusions (FTLD-TDP) and FTLD with tau inclusions (FTLD-Tau). Post-mortem human tissue from the superior frontal gyrus (SFG) of FTLD-TDP (n = 15), FTLD-Tau (n = 8) and aged Control cases (n = 6) was immunolabelled using antibodies against non-phosphorylated neurofilaments (SMI32 antibody), calretinin and NeuN, to explore neuronal cell loss. The presence of non-phosphorylated neurofilament immunolabelling in axons of the SFG white matter was also quantified as a measure of axon pathology, as axonal neurofilaments are normally phosphorylated. We demonstrate the selective loss of neurofilament-expressing neurons in both FTLD-TDP and FTLD-Tau cases compared to aged Controls. We also show that non-phosphorylated neurofilament axonal pathology in the SFG white matter was associated with increasing age, but not FTLD. This data suggests neurofilament-expressing neurons are vulnerable in both FTLD-TDP and FTLD-Tau.

Neonicotinoid pesticides: evidence of developmental neurotoxicity from regulatory rodent studies.

Neonicotinoids are the most widely used class of insecticides in the United States (U.S.). and the world. Consistent with their high use and persistence, neonicotinoids are often found contaminating drinking water and food. They are also detected in human urine, breast milk, amniotic and cerebrospinal fluids, as well as the brains of treated rodents. Neonicotinoids were once thought to pose little neurotoxic risk to humans, but a growing body of research challenges that assumption. In this study we provide the first comprehensive assessment of unpublished rodent developmental neurotoxicity (DNT) studies on five neonicotinoids that were submitted to the U.S. Environmental Protection Agency (EPA) by neonicotinoid manufacturers. Groups of female rats were administered three different doses of a neonicotinoid during pregnancy and lactation, and their offspring subjected to various neurological tests and brain measurements. We identified nicotine-like effects such as reduced brain size, indicative of neuronal cell loss. Statistically significant shrinkage of brain tissue was observed in high-dose offspring for five neonicotinoids: acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam. Two brain regions reduced in the rodent studies-the corpus callosum and caudate-putamen-tend to be smaller in people diagnosed with attention-deficit hyperactivity disorder (ADHD), and in children of mothers who smoked during pregnancy, suggesting a possible link between perinatal neonicotinoid exposure and ADHD. A decreased auditory startle reflex was reported for acetamiprid at all doses and was statistically significant in the mid- and high-dose offspring, and for clothianidin in juvenile high-dose females. No mid- or low-dose brain morphometric data were submitted for acetamiprid, imidacloprid, or thiacloprid. Thiamethoxam mid- and low-dose brain morphometric data were provided to EPA upon request. Only partial mid-dose brain morphometry data were submitted for clothianidin, but no low-dose data. Yet despite this lack of data, EPA concluded that only the high-dose brain morphometric effects were treatment-related-setting the mid-dose as the study's No Observed Adverse Effect Level (NOAEL) or failing to find a definitive NOAEL for acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam. We found numerous deficiencies in EPA's regulatory oversight and data analyses. EPA dismissed statistically significant adverse effects, accepted substandard DNT studies despite lack of valid positive control data, and allowed neonicotinoid registrants to unduly influence agency decision-making. We conclude that perinatal exposure to neonicotinoids and their metabolites induces adverse, nicotine-like neurotoxic effects in rodent bioassays, and that the exposure limits set by EPA for human exposure are either not protective or not supported by available neurotoxicity data. We propose regulatory changes to empower EPA to better protect public health from developmental neurotoxins like neonicotinoids.

Neurexin1 level in Huntington's Disease and decreased Neurexin1 in disease progression.

Huntington's disease (HD) is a neurodegenerative disorder characterized by the presence of abnormally expanded polyglutamine tracts in huntingtin protein (HTT). Mutant HTT disrupts synaptic transmission and plasticity, particularly in the striatum and cortex, leading to early dysfunctions, such as altered neurotransmitter release, impaired synaptic vesicle recycling, and disrupted postsynaptic receptor function. Synaptic loss precedes neuronal degeneration and contributes to disease progression. Neurexin1 (NRXN1), a synaptic cell adhesion molecule primarily located in the presynaptic membrane, plays a crucial role in maintaining synaptic integrity. The present study investigated the role of NRXN1 in HD. This study researched whether the changed level has been related to expanded polyQ stretch and disease progression. Here, we report a reduction in NRXN1 levels in post-symptomatic HD mice and in neuronal cells expressing abnormally expanded polyQ tracts. Mutant HTT was found to decrease NRXN1 levels while increasing LAMP2A levels, which promotes lysosomal degradation of NRXN1. In HD cells expressing Q111, downregulated LAMP2A restored NRXN1 levels and maintained cell proliferation compared with cells expressing Q7. These findings suggest that NRXN1 is regulated by LAMP2A-mediated way and that decreased NRXN1 levels are associated with symptomatic progression and neuronal cell loss in HD.

GSK-3β inhibitor amplifies autophagy-lysosomal pathways by regulating TFEB in Parkinson's disease models

Parkinson's disease (PD), a common neurodegenerative disorder characterized by degeneration of the substantia nigra and a marked increase in Lewy bodies in the brain, primarily manifests as motor dysfunction. Glycogen synthase kinase-3 beta (GSK-3β) is known to play a critical role in various pathological processes of neurodegenerative diseases. However, the impact of GSK-3β inhibitors on PD progression and the underlying molecular mechanisms responsible for the effects have not been fully elucidated. Using in vitro and mouse models of 1-methyl-4-phenylpyridine (MPP+)-or methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD, we found that inhibition of GSK-3β activity alleviated mitochondrial damage, cell apoptosis, and neuronal cell loss by promoting the nuclear translocation of transcription factor EB (TFEB), thereby amplifying the autophagy-lysosomal pathway (ALP). Importantly, siRNA silencing of the TFEB gene impaired the GSK-3β inhibitor-mediated activation of the ALP pathway, thus negating the metabolic support required for neuronal functional improvement. Short-term treatment with the GSK-3β inhibitor significantly ameliorated motor dysfunction and improved motor coordination in model mice with MPTP-induced PD. GSK-3β inhibition increased the ALP and TFEB activities in the mice, thereby reducing α-synuclein aggregation and neuronal damage. In conclusion, our study demonstrates that inhibition of GSK-3β activity can delay the pathological processes of PD via promotion of the TFEB–ALP pathway, potentially providing a novel therapeutic target for this neurodegenerative disorder.

Transcriptomic and metabolomic changes might predict frailty in SAMP8 mice.

Frailty is a geriatric, multi-dimensional syndrome that reflects multisystem physiological change and is a transversal measure of reduced resilience to negative events. It is characterized by weakness, frequent falls, cognitive decline, increased hospitalization and dead and represents a risk factor for the development of Alzheimer's disease (AD). The fact that frailty is recognized as a reversible condition encourages the identification of earlier biomarkers to timely predict and prevent its occurrence. SAMP8 (Senescence-Accelerated Mouse Prone-8) mice represent the most appropriate preclinical model to this aim and were used in this study to carry transcriptional and metabolic analyses in the brain and plasma, respectively, upon a characterization at cognitive, motor, structural, and neuropathological level at 2.5, 6, and 9 months of age. At 2.5 months, SAMP8 mice started displaying memory deficits, muscle weakness, and motor impairment. Functional alterations were associated with a neurodevelopmental deficiency associated with reduced neuronal density and glial cell loss. Through transcriptomics, we identified specific genetic signatures well distinguishing SAMP8 mice at 6 months, whereas plasma metabolomics allowed to segregate SAMP8 mice from SAMR1 already at 2.5 months of age by detecting constitutively lower levels of acylcarnitines and lipids in SAMP8 at all ages investigated correlating with functional deficits and neuropathological signs. Our findings suggest that specific genetic alterations at central level, as well as metabolomic changes in plasma, might allow to early assess a frail condition leading to dementia development, which paves the foundation for future investigation in a clinical setting.

Translational Research and Therapies for Neuroprotection and Regeneration of the Optic Nerve and Retina: A Narrative Review

Most retinal and optic nerve diseases pose significant threats to vision, primarily due to irreversible retinal neuronal cell death, a permanent change, which is a critical factor in their pathogenesis. Conditions such as glaucoma, retinitis pigmentosa, diabetic retinopathy, and age-related macular degeneration are the top four leading causes of blindness among the elderly in Japan. While standard treatments—including reduction in intraocular pressure, anti-vascular endothelial growth factor therapies, and retinal photocoagulation—can partially delay disease progression, their therapeutic effects remain limited. To address these shortcomings, a range of neuroprotective and regenerative therapies, aimed at preventing retinal neuronal cell loss, have been extensively studied and increasingly integrated into clinical practice over the last two decades. Several of these neuroprotective therapies have achieved on-label usage worldwide. This narrative review introduces several neuroprotective and regenerative therapies for retinal and optic nerve diseases that have been successfully translated into clinical practice, providing foundational knowledge and success stories that serve as valuable references for researchers in the field.

Pathological Involvement of Protein Phase Separation and Aggregation in Neurodegenerative Diseases.

Neurodegenerative diseases are the leading cause of human disability and immensely reduce patients' life span and quality. The diseases are characterized by the functional loss of neuronal cells and share several common pathogenic mechanisms involving the malfunction, structural distortion, or aggregation of multiple key regulatory proteins. Cellular phase separation is the formation of biomolecular condensates that regulate numerous biological processes, including neuronal development and synaptic signaling transduction. Aberrant phase separation may cause protein aggregation that is a general phenomenon in the neuronal cells of patients suffering neurodegenerative diseases. In this review, we summarize the pathological causes of common neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease, among others. We discuss the regulation of key amyloidogenic proteins with an emphasis of their aberrant phase separation and aggregation. We also introduce the approaches as potential therapeutic strategies to ameliorate neurodegenerative diseases through intervening protein aggregation. Overall, this review consolidates the research findings of phase separation and aggregation caused by misfolded proteins in a context of neurodegenerative diseases.

Significance of Programmed Cell Death Pathways in Neurodegenerative Diseases.

Programmed cell death (PCD) is a form of cell death distinct from accidental cell death (ACD) and is also referred to as regulated cell death (RCD). Typically, PCD signaling events are precisely regulated by various biomolecules in both spatial and temporal contexts to promote neuronal development, establish neural architecture, and shape the central nervous system (CNS), although the role of PCD extends beyond the CNS. Abnormalities in PCD signaling cascades contribute to the irreversible loss of neuronal cells and function, leading to the onset and progression of neurodegenerative diseases. In this review, we summarize the molecular processes and features of different modalities of PCD, including apoptosis, necroptosis, pyroptosis, ferroptosis, cuproptosis, and other novel forms of PCD, and their effects on the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), multiple sclerosis (MS), traumatic brain injury (TBI), and stroke. Additionally, we examine the key factors involved in these PCD signaling pathways and discuss the potential for their development as therapeutic targets and strategies. Therefore, therapeutic strategies targeting the inhibition or facilitation of PCD signaling pathways offer a promising approach for clinical applications in treating neurodegenerative diseases.

Acute and chronic excitotoxicity in ischemic stroke and late-onset Alzheimer's disease.

Stroke and Alzheimer's disease are common neurological disorders and often occur in the same individuals. The comorbidity of the two neurological disorders represents a grave health threat to older populations. This review presents a brief background of the development of novel concepts and their clinical potentials. The activity of glutamatergic N-methyl-D-aspartate receptors and N-methyl-D-aspartate receptor-mediated Ca 2+ influx is critical for neuronal function. An ischemic insult induces prompt and excessive glutamate release and drastic increases of intracellular Ca 2+ mainly via N-methyl-D-aspartate receptors, particularly of those at the extrasynaptic site. This Ca 2+ -evoked neuronal cell death in the ischemic core is dominated by necrosis within a few hours and days known as acute excitotoxicity. Furthermore, mild but sustained Ca 2+ increases under neurodegenerative conditions such as in the distant penumbra of the ischemic brain and early stages of Alzheimer's disease are not immediately toxic, but gradually set off deteriorating Ca 2+ -dependent signals and neuronal cell loss mostly because of activation of programmed cell death pathways. Based on the Ca 2+ hypothesis of Alzheimer's disease and recent advances, this Ca 2+ -activated "silent" degenerative excitotoxicity evolves from years to decades and is recognized as a unique slow and chronic neuropathogenesis. The N-methyl-D-aspartate receptor subunit GluN3A, primarily at the extrasynaptic site, serves as a gatekeeper for the N-methyl-D-aspartate receptor activity and is neuroprotective against both acute and chronic excitotoxicity. Ischemic stroke and Alzheimer's disease, therefore, share an N-methyl-D-aspartate receptor- and Ca 2+ -mediated mechanism, although with much different time courses. It is thus proposed that early interventions to control Ca 2+ homeostasis at the preclinical stage are pivotal for individuals who are susceptible to sporadic late-onset Alzheimer's disease and Alzheimer's disease-related dementia. This early treatment simultaneously serves as a preconditioning therapy against ischemic stroke that often attacks the same individuals during abnormal aging.

The Effects of Cathepsin B Inhibition in the Face of Diffuse Traumatic Brain Injury and Secondary Intracranial Pressure Elevation.

Traumatic brain injury (TBI) affects millions of people each year. Previous studies using the central fluid percussion injury (CFPI) model in adult male rats indicated that elevated intracranial pressure (ICP) was associated with long-term effects, including neuronal cell loss and increased sensory sensitivity post-injury and secondary ICP elevation, which were not seen following injury alone. Investigations also indicated that cathepsin B (Cath B), a lysosomal cysteine protease, may play a role in the pathological progression of neuronal membrane disruption; however, the specific impact of Cath B inhibition following CFPI remained unknown. Thus, the focus of this study was to evaluate the effects of Cath B inhibition via the intracerebroventricular infusion of the Cath B inhibitor to the CA-074 methyl ester (CA-074Me) 2w following injury with or without secondary ICP elevation. This was accomplished using adult male rats continuously infused with CA-074Me or 10% DMSO as a vehicle control for 2w following either sham injury, CFPI only, or CFPI with subsequent ICP elevation to 20 mmHg. We assessed Cath B activity and evaluated the protein levels of Cath B and Cath B-binding partners AIF, Bcl-XL, and Bak. We also conducted histological analyses of the total cell counts to assess for cell loss, membrane disruption, and Cath B localization. Finally, we investigated somatosensory changes with the whisker nuisance task. Overall, this study demonstrated that Cath B is not a direct driver of membrane disruption; however, the administration of CA-074Me alters Cath B localization and reduces hypersensitivity, emphasizing Cath B as an important component in late secondary pathologies.

Histomorphology and Histomorphometrics of the retina in Juvenile and Adult African Giant Rats (Cricetomys gambianus)

Aging is accompanied with various forms of functional ultrastructural and morphological changes in the eye, including the retina, leading to vision deterioration. However, age related retinal degenerative changes requires further elucidation especially as all previous studies on age-related change of the retina were done in mutant mouse strain models of hereditary retinal degenerations. The potential of using African giant rats (AGRs) as models for ageing in the eye, especially retina, was explored in this study. A total of 14 AGRs divided into two age groups (juvenile and adult) were used to study the histomorphology and histomorphometrics of the retina as well as retinal astrocyte morphology and heterogeneity. Histological findings included retinal atrophy and hypoplasia, with cellular swellings of neuronal cell populations and astrocytes soma and ramifications in the retina of adult compared to juvenile AGR. We suggest that AGR be used as animal model for translational research into normal aging process of the retina, as well as to elucidate the process of age-related neuronal cells loss.

Molecular Crossfires between Inflammasome Signalling and Dietary Small Molecule Inhibitors in Neurodegenerative Diseases: Implications for Medical Nutrition Therapy

Neurodegenerative disorders are a range of debilitating conditions that manifest due to the progressive loss of neuronal cells in specific brain regions. Current therapeutic options are less than adequate in many respects. Protein misfolding and aggregation are hallmarks of the most common neurodegenerative disorders. Consequently, they elicit cellular homeostasis disruption, synaptic connection loss, and subsequent cellular apoptosis. In recent years, research has increasingly linked dysregulated inflammatory responses mediated by the inflammasome complex to several neurodegenerative conditions, such as Alzheimer's disease, Parkinson's disease, Epilepsy, Huntington’s disease, Autism, stroke etc. The inflammasome is a cytosolic multiprotein complex that is essential for innate immunity. Microglia are the primary cells expressing inflammasomes in the central nervous system, although astrocytes, neurons, and infiltrating myeloid cells can also express and activate inflammasomes. Regrettably, dysregulated inflammasome signaling upregulates the release of pro-inflammatory cytokines, as well as activating caspase-1. This process contributes to the continuation of neuroinflammation and subsequent damage to neurons. In this review of existing literatures, we collated empirical evidences about various inflammasome signaling pathways in selected neurological disorders. Majorly, we emphasised their influence on the advancement of diseases and neuronal cell death. Available empirical data showed that dietary small molecule inhibitors offer multi-targeted interactions to inhibit inflammasome signalling and upstream neuroinflammation. Notably, the baseline mechanisms involve suppression of free radicals, downregulating NF-κB and NLRP3 oligomerization, activating anti-inflammatory pathways, reducing ER stress, and modulating the Nrf2-ARE pathway. This shows promise for developing innovative medical nutrition therapies for various neurological conditions.

Zinc Oxide Nanoparticles Attenuated Neurochemical and Histopathological Alterations Associated with Aluminium Chloride Intoxication in Rats.

The present investigation explored the potential neuroprotective role of zinc oxide nanoparticles (ZnONPs) on aluminum chloride (AlCl3)-mediated Alzheimer's disease (AD)-like symptoms. Rats were distributed into four treatment groups equally: control, ZnONPs (4mg/kg b.wt.), AlCl3 (100mg/kg b.wt.), and ZnONPs + AlCl3 groups. Rats were treated for 42 consecutive days. ZnONPs injection into AlCl3-treated rats suppressed the development of oxidative challenge in the cortical and hippocampal tissues, as demonstrated by the decreased neuronal pro-oxidants (malondialdehyde and nitric oxide), and the increased glutathione and catalase levels. Additionally, ZnONPs injection showed anti-inflammatory potency in response to AlCl3 by decreasing levels of tumor necrosis factor-α and interleukin-1β. Moreover, pretreatment with ZnONPs prevented neuronal cell loss by decreasing the level of pro-apoptotic caspase-3 and enhancing the anti-apoptotic B cell lymphoma 2. Furthermore, ZnONPs ameliorated the disturbed acetylcholinesterase activity, monoamines (norepinephrine, dopamine, and serotonin), excitatory (glutamic and aspartic acids), and inhibitory amino acids (GABA and glycine) in response to AlCl3 exposure. These findings indicate that ZnONPs may have the potential as an alternative therapy to minimize or prevent the neurological deficits in AD model by exhibiting antioxidative, anti-inflammation, anti-apoptosis, and neuromodulatory effects.

Step-down infusion of barbiturate improves neurofunction in a new rat model of rebleeding subarachnoid hemorrhage

Rebleeding from a ruptured aneurysm is a risk factor for fatal prognosis in subarachnoid hemorrhage (SAH). A novel barbiturate treatment, step-down infusion of barbiturate (sd-B), was previously developed; it showed beneficial effects on patients with severe traumatic brain injuries. The present study established a rebleeding SAH model in rats and evaluated the effect of sd-B. Fifty male Sprague-Dawley rats were divided into sham-operation with distilled water, sham-operation with barbiturate, SAH-rebleeding with distilled water, and SAH-rebleeding with barbiturate groups. For posttreatment with sd-B, thiamylal was intraperitoneally administered at 3 mg/kg/h on days 0–1, 2 mg/kg/h on days 1–2, and 1 mg/kg/h on days 2–3 after SAH using osmotic minipumps. We monitored neurofunction and case fatality as the primary endpoints and evaluated brain injuries, including brain edema and cortical neuronal cell death, as the secondary endpoints. Posttreatment with sd-B improved the modified Garcia test, reduced the brain water content, and inhibited the loss of neuronal cells and microglial expressions in the rat model. Our results revealed that sd-B ameliorated neurofunction and brain injuries on the rebleeding SAH model, suggesting that the novel treatment is a good candidate drug for patients with SAH with rebleeding.

Calcium Modulating Effect of Polycyclic Cages: A Suitable Therapeutic Approach Against Excitotoxic-induced Neurodegeneration.

Neurodegenerative disorders pose a significant challenge to global healthcare systems due to their progressive nature and the resulting loss of neuronal cells and functions. Excitotoxicity, characterized by calcium overload, plays a critical role in the pathophysiology of these disorders. In this review article, we explore the involvement of calcium dysregulation in neurodegeneration and neurodegenerative disorders. A promising therapeutic strategy to counter calcium dysregulation involves the use of calcium modulators, particularly polycyclic cage compounds. These compounds, structurally related to amantadine and memantine, exhibit neuroprotective properties by attenuating calcium influx into neuronal cells. Notably, the pentacycloundecylamine NGP1-01, a cage-like structure, has shown efficacy in inhibiting both N-methyl-D-aspartate (NMDA) receptors and voltage- gated calcium channels (VGCCs), making it a potential candidate for neuroprotection against excitotoxic-induced neurodegenerative disorders. The structure-activity relationship of polycyclic cage compounds is discussed in detail, highlighting their calcium-inhibitory activities. Various closed, open, and rearranged cage compounds have demonstrated inhibitory effects on calcium influx through NMDA receptors and VGCCs. Additionally, these compounds have exhibited neuroprotective properties, including free radical scavenging, attenuation of neurotoxicities, and reduction of neuroinflammation. Although the calcium modulatory activities of polycyclic cage compounds have been extensively studied, apart from amantadine and memantine, none have undergone clinical trials. Further in vitro and in vivo studies and subsequent clinical trials are required to establish the efficacy and safety of these compounds. The development of polycyclic cages as potential multifunctional agents for treating complex neurodegenerative diseases holds great promise.

Sodium Houttuyfonate Prevents Seizures and Neuronal Cell Loss by Maintaining Glutamatergic System Stability in Male Rats with Kainic Acid-Induced Seizures.

The present study evaluated the antiseizure and neuroprotective effects of sodium houttuyfonate (SH), a derivative of Houttuynia cordata Thunb. (H. cordata), in a kainic acid (KA)- induced seizure rat model and its underlying mechanism. Sprague Dawley rats were administered normal saline, SH (50 or 100 mg/kg), or carbamazepine (300 mg/kg) by oral gavage for seven consecutive days before the intraperitoneal administration of KA (15 mg/kg). SH showed antiseizure effects at a dose of 100 mg/kg; it prolonged seizure latency and decreased seizure scores. SH also significantly decreased neuronal loss in the hippocampi of KA-treated rats, which was associated with the prevention of glutamate level increase, the upregulation of glutamate reuptake-associated proteins (excitatory amino acid transporters 1-3), glutamate metabolism enzyme glutamine synthetase, the downregulation of the glutamate synthesis enzyme glutaminase, and significant alterations in the expression of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor) and NMDA (N-methyl-D-aspartic acid receptor) receptor subunits in the hippocampus. Furthermore, the effects of SH were similar to those of the antiseizure drug carbamazepine. Therefore, the results of the present study suggest that SH has antiseizure effects on KA-induced seizures, possibly through the prevention of glutamatergic alterations. Our findings suggest that SH is a potential alternative treatment that may prevent seizures by preserving the normal glutamatergic system.

The protective effect of venlafaxine on hydrogen peroxide-induced cytotoxicity in C6 glioma cells

Aim: Neurodegeneration is the progressive loss and structural deterioration of neuronal cells. Hydrogen peroxide (H2O2) is formed by dismutation and causes oxidative stress in neuronal cells. Venlafaxine is a drug that increases both serotonin and noradrenaline in the synaptic gap.In this study, the effect of venlafaxine on H2O2-induced cytotoxicity in C6 cells was investigated. Methods: First of all, different doses of venlafaxine (25, 50, and 100 µM) were tried to find the appropriate dose in C6 glioma cells. Then, the effect of venlafaxine on H2O2-induced cytotoxicity in the cells was investigated. For this purpose, cell viability rate, proinflammatory markers IL-1β and TNF-α, and NO and iNOS levels were examined by ELISA kits. Results: H2O2-treated caused cytotoxicity in the C6 glioma cells; when venlafaxine 25, 50, and 100 μM doses were evaluated in terms of cell viability, it was observed that the 100 μM venlafaxine applied group significantly increased cell viability compared to the other groups. When we look at the levels of IL-1β and TNF-α, it is observed that there is an increase in the H2O2 applied group and a significant decrease in the venlafaxine (100 μM) applied group. It was observed that NO and iNOS levels increased in the H2O2 applied group compared to the other groups. It was observed that Venlafaxine treatment reduced the increased NO and iNOS levels caused by H2O2. Conclusion: The study results showed that venlafaxine may have a protective effect on H2O2-induced cytotoxicity in C6 glioma cells.

Early treatment with rifaximin during epileptogenesis reverses gut alterations and reduces seizure duration in a mouse model of acquired epilepsy

The gut microbiota is altered in epilepsy and is emerging as a potential target for new therapies. We studied the effects of rifaximin, a gastrointestinal tract-specific antibiotic, on seizures and neuropathology and on alterations in the gut and its microbiota in a mouse model of temporal lobe epilepsy (TLE).Epilepsy was induced by intra-amygdala kainate injection causing status epilepticus (SE) in C57Bl6 adult male mice. Sham mice were injected with vehicle. Two cohorts of SE mice were fed a rifaximin-supplemented diet for 21 days, starting either at 24 h post-SE (early disease stage) or at day 51 post-SE (chronic disease stage). Corresponding groups of SE mice (one each disease stage) were fed a standard (control) diet. Cortical ECoG recording was done at each disease stage (24/7) for 21 days in all SE mice to measure the number and duration of spontaneous seizures during either rifaximin treatment or control diet. Then, epileptic mice ± rifaximin and respective sham mice were sacrificed and brain, gut and feces collected. Biospecimens were used for: (i) quantitative histological analysis of the gut structural and cellular components; (ii) markers of gut inflammation and intestinal barrier integrity by RTqPCR; (iii) 16S rRNA metagenomics analysis in feces. Hippocampal neuronal cell loss was assessed in epileptic mice killed in the early disease phase.Rifaximin administered for 21 days post-SE (early disease stage) reduced seizure duration (p < 0.01) and prevented hilar mossy cells loss in the hippocampus compared to epileptic mice fed a control diet. Epileptic mice fed a control diet showed a reduction of both villus height and villus height/crypt depth ratio (p < 0.01) and a decreased number of goblet cells (p < 0.01) in the duodenum, as well as increased macrophage (Iba1)-immunostaining in the jejunum (p < 0.05), compared to respective sham mice.Rifaximin’s effect on seizures was associated with a reversal of gut structural and cellular changes, except for goblet cells which remained reduced. Seizure duration in epileptic mice was negatively correlated with the number of mossy cells (p < 0.01) and with villus height/crypt depth ratio (p < 0.05).Rifaximin-treated epileptic mice also showed increased tight junctions (occludin and ZO-1, p < 0.01) and decreased TNF mRNA expression (p < 0.01) in the duodenum compared to epileptic mice fed a control diet.Rifaximin administered for 21 days in chronic epileptic mice (chronic disease stage) did not change the number or duration of seizures compared to epileptic mice fed a control diet. Chronic epileptic mice fed a control diet showed an increased crypt depth (p < 0.05) and reduced villus height/crypt depth ratio (p < 0.01) compared to respective sham mice. Rifaximin treatment did not affect these intestinal changes.At both disease stages, rifaximin modified α- and β-diversity in epileptic and sham mice compared to respective mice fed a control diet. The microbiota composition in epileptic mice, as well as the effects of rifaximin at the phylum, family and genus levels, depended on the stage of the disease. During the early disease phase, the abundance of specific taxa was positively correlated with seizure duration in epileptic mice.In conclusion, gut-related alterations reflecting a dysfunctional state, occur during epilepsy development in a TLE mouse model. A short-term treatment with rifaximin during the early phase of the disease, reduced seizure duration and neuropathology, and reversed some intestinal changes, strengthening the therapeutic effects of gut-based therapies in epilepsy.

Metabolomics analysis revealed the neuroprotective role of 2-phosphoglyceric acid in hypoxic-ischemic brain damage through GPX4/ACSL4 axis regulation

Hypoxic-ischemic brain damage (HIBD) is a cerebral injury resulting from the combination of ischemia and hypoxia in neonatal brain tissue. Presently, there exists no efficacious remedy for HIBD. A mounting body of evidence indicates that dynamic metabolites formed during metabolic procedures assume a vital role in neuronal maturation and recuperation. However, it remains unclear whether any endogenous metabolites are involved in the pathogenesis of HIBD. Here, an untargeted metabolomics analysis was conducted by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry (GC/LC-MS) in OGD/R (oxygen-glucose deprivation/reoxygenation)-induced HT-22 cells. We observed that ferroptosis signaling plays an essential role in HI-induced neuronal injury. Interestingly, we also found that the differentially expressed metabolite, 2-phosphoglyceric acid, significantly improved the neuronal cell survival of OGD/R HT-22 cells by inhibiting ferroptosis. Moreover, 2-phosphoglyceric acid effectively rescued the cell activity of HT-22 cells treated with the ferroptosis inducer RSL-3. Furthermore, 2-phosphoglyceric acid alleviated cerebral infarction and reduced HIBD-induced neuronal cell loss of the central nervous system in neonatal rats by regulating GPX4 expression. Taken together, we found that 2-phosphoglyceric acid, which was downregulated in HT-22 cells induced by OGD/R, exerted neuronal protective effects on OGD/R-treated HT-22 cells and HIBD-induced neonatal rats by inhibiting hypoxic-ischemic-induced ferroptosis through the regulation of the GPX4/ACSL4 axis.

Mutant α-synuclein causes death of human cortical neurons via ERK1/2 and JNK activation

Synucleinopathies refer to a group of disorders characterized by SNCA/α-synuclein (α-Syn)-containing cytoplasmic inclusions and neuronal cell loss in the nervous system including the cortex, a common feature being cognitive impairment. Still, the molecular pathogenesis of cognitive decline remains poorly understood, hampering the development of effective treatments. Here, we generated induced pluripotent stem cells (iPSCs) derived from familial Parkinson’s disease (PD) patients carrying SNCA A53T mutation, differentiating them into cortical neurons by a direct conversion method. Patient iPSCs-derived cortical neurons harboring mutant α-Syn exhibited increased α-Syn-positive aggregates, shorter neurites, and time-dependent vulnerability. Furthermore, RNA-sequencing analysis, followed by biochemical validation, identified the activation of the ERK1/2 and JNK cascades in cortical neurons with SNCA A53T mutation. This result was consistent with a reverted phenotype of neuronal death in cortical neurons when treated with ERK1/2 and JNK inhibitors, respectively. Our findings emphasize the role of ERK1/2 and JNK cascades in the vulnerability of cortical neurons in synucleinopathies, and they could pave the way toward therapeutic advancements for synucleinopathies.