Glyphosate Exposure Associated with Human Neurodegenerative Disorders: A Scoping Review

Chemically engineered agricultural products such as pesticides, insecticides, and herbicides, although used considerably for both industrialized and personal agricultural use, have recently been associated with a number of serious human health disorders. This rapid literature review aims to accumulate and analyze research from the last ten years, focusing specifically on the effects of exposure to glyphosate-based herbicide products such as Roundup as associated with the formation of various neurological disorders. Specifically, this review focuses on laboratory research using animal models or human cell cultures as well as human population-based epidemiological studies. It associates exposure to glyphosate or glyphosate-based products with the formation or exacerbation of neurological disorders such as Parkinson’s disease, Alzheimer’s disease, seizures, and autism spectrum disorder. In addition, it examines the correlation between the gut-brain axis, exposure to glyphosate, and neurodegeneration.

Targeting TrkB–PSD-95 coupling to mitigate neurological disorders

Tropomyosin receptor kinase B(TrkB)signaling plays a pivotal role in dendritic growth and dendritic spine formation to promote learning and memory.The activity-dependent release of brain-derived neurotrophic factor at synapses binds to pre-or postsynaptic TrkB resulting in the strengthening of synapses,reflected by long-term potentiation.Postsynaptically,the association of postsynaptic density protein-95 with TrkB enhances phospholipase Cγ-Ca^(2+)/calmodulin-dependent protein kinaseⅡand phosphatidylinositol 3-kinase-mechanistic target of rapamycin signaling required for long-term potentiation.In this review,we discuss TrkB-postsynaptic density protein-95 coupling as a promising strategy to magnify brain-derived neurotrophic factor signaling towards the development of novel therapeutics for specific neurological disorders.A reduction of TrkB signaling has been observed in neurodegenerative disorders,such as Alzheimer's disease and Huntington's disease,and enhancement of postsynaptic density protein-95 association with TrkB signaling could mitigate the observed deficiency of neuronal connectivity in schizophrenia and depression.Treatment with brain-derived neurotrophic factor is problematic,due to poor pharmacokinetics,low brain penetration,and side effects resulting from activation of the p75 neurotrophin receptor or the truncated TrkB.T1 isoform.Although TrkB agonists and antibodies that activate TrkB are being intensively investigated,they cannot distinguish the multiple human TrkB splicing isoforms or cell type-specific functions.Targeting TrkB–postsynaptic density protein-95 coupling provides an alternative approach to specifically boost TrkB signaling at localized synaptic sites versus global stimulation that risks many adverse side effects.

Exploring the interaction between the gut microbiota and cyclic adenosine monophosphate-protein kinase A signaling pathway:a potential therapeutic approach for neurodegenerative diseases

The interaction between the gut microbiota and cyclic adenosine monophosphate(cAMP)-protein kinase A(PKA)signaling pathway in the host's central nervous system plays a crucial role in neurological diseases and enhances communication along the gut–brain axis.The gut microbiota influences the cAMP-PKA signaling pathway through its metabolites,which activates the vagus nerve and modulates the immune and neuroendocrine systems.Conversely,alterations in the cAMP-PKA signaling pathway can affect the composition of the gut microbiota,creating a dynamic network of microbial-host interactions.This reciprocal regulation affects neurodevelopment,neurotransmitter control,and behavioral traits,thus playing a role in the modulation of neurological diseases.The coordinated activity of the gut microbiota and the cAMP-PKA signaling pathway regulates processes such as amyloid-β protein aggregation,mitochondrial dysfunction,abnormal energy metabolism,microglial activation,oxidative stress,and neurotransmitter release,which collectively influence the onset and progression of neurological diseases.This study explores the complex interplay between the gut microbiota and cAMP-PKA signaling pathway,along with its implications for potential therapeutic interventions in neurological diseases.Recent pharmacological research has shown that restoring the balance between gut flora and cAMP-PKA signaling pathway may improve outcomes in neurodegenerative diseases and emotional disorders.This can be achieved through various methods such as dietary modifications,probiotic supplements,Chinese herbal extracts,combinations of Chinese herbs,and innovative dosage forms.These findings suggest that regulating the gut microbiota and cAMP-PKA signaling pathway may provide valuable evidence for developing novel therapeutic approaches for neurodegenerative diseases.

Mesenchymal stem cells-based therapy as a potential treatment in neurodegenerative disorders: is the escape from senescence an answer?

Aging is the most prominent risk factor contributing to the development of neurodegenerative disorders. In the United States, over 35 million of elderly people suffer from age-related diseases. Aging impairs the self-repair ability of neuronal cells, which undergo progressive deterioration. Once initiated, this process hampers the already limited regenerative power of the central nervous system, making the search for new therapeutic strategies particularly difficult in elderly affected patients. So far, mesenchymal stem cells have proven to be a viable option to ameliorate certain aspects of neurodegeneration, as they possess high proliferative rate and differentiate in vitro into multiple lineages. However, accumulating data have demonstrated that during longterm culture, mesenchymal stem cells undergo spontaneous transformation. Transformed mesenchymal stem cells show typical features of senescence, including the progressive shortening of telomers, which results in cell loss and, as a consequence, hampered regenerative potential. These evidences, in line with those observed in mesenchymal stem cells isolated from old donors, suggest that senescence may represent a limit to mesenchymal stem cells exploitation in therapy, prompting scholars to either find alternative sources of pluripotent cells or to arrest the age-re- lated transformation. In the present review, we summarize findings from recent literature, and critically discuss some of the major hurdles encountered in the search of appropriate sources of mesenchymal stem cells, as well as benefits arising from their use in neurodegenerative diseases. Finally, we provide some insights that may aid in the development of strategies to arrest or, at least, delay the aging of mesenchymal stem cells to improve their therapeutic potential.

Cross-talk between T-cells and gut-microbiota in neurodegenerative disorders

The emerging role of gut microbiota as a key player in the development of neurodegenerative disorders: Mammals have evolved together with commensal microbiota to establish a symbiotic relationship in which they regulate reciprocally by synthesizing and responding to several common chemical substances. In this regard, gut microbiota constitutes a consortium of bacteria that not only participates in the degradation of nutrients, but also produces metabolites, fatty acids and neurotransmitters that can act on the enzymes and receptors expressed in eukaryotic cells, which considerably affects the physiology of the host and contribute to maintaining homeostasis (Lyte, 2013).

Decoding degeneration:the implementation of machine learning for clinical detection of neurodegenerative disorders

Machine learning represents a growing subfield of artificial intelligence with much promise in the diagnosis,treatment,and tracking of complex conditions,including neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases.While no definitive methods of diagnosis or treatment exist for either disease,researchers have implemented machine learning algorithms with neuroimaging and motion-tracking technology to analyze pathologically relevant symptoms and biomarkers.Deep learning algorithms such as neural networks and complex combined architectures have proven capable of tracking disease-linked changes in brain structure and physiology as well as patient motor and cognitive symptoms and responses to treatment.However,such techniques require further development aimed at improving transparency,adaptability,and reproducibility.In this review,we provide an overview of existing neuroimaging technologies and supervised and unsupervised machine learning techniques with their current applications in the context of Alzheimer’s and Parkinson’s diseases.

Is glial heme oxygenase-1 suppression in neurodegenerative disorders permissive for neural repair?

＇Core＇ neuropathology of degenerative central nervous system （CNS） disorders The common human neurodegenerative disorders （Alzheimer＇s disease （AD）, Parkinson＇s disease （PD）, amyotrophic lateral sclerosis, etc.） vary with respect to risk factors, ages of onset, sex predilections, neuraxial regions affected, hallmark cellular inclusions, behavioral and neurological symptoms, and responses to treatment. Despite these differences, there appears to be a set of ＇core＇ neuropathological features shared among these and related entities. Common to these conditions are 1） pathological deposition of non-transferrin bound iron, 2） oxidative stress and associated protein, lipid and nucleic acid modifications, 3） mitochondrial membrane damage and bioenergetic failure, and 4） macroautophagy in the affected neural tissues.

Bioelemental patterns in the cerebrospinal fluid as potential biomarkers for neurodegenerative disorders

Neurodegenerative disorders like Parkinson＇s disease （PD） or atypi- cal Parkinsonian syndromes including the different synucleinopa- thies and tauopathies are an important burden for patients, rela- tives, care providers and incur mounting costs for the health care system in our aging society.

Copper interactions with DNA of chromatin and its role in neurodegenerative disorders

In this study, we have demonstrated the conformational changes to DNA induced by abnormal interactions of copper using circular dichroism, in combination with UV-absorbance and fluorescence spectroscopy. Results confirm that binding of copper to bases of DNA in chromatin is concentration dependent. Binding efficiency of Cu2~ ions to DNA is increased in proportion to the degree of unwinding of the double helix induced by denaturation. Altered B-DNA conformation will alter the integrity of DNA which may affect the normal process of DNA replication and transcription. Copper induced DNA damage in the brain may cause neurotoxicity and the neuronal cell death and is implicated in Alzheimer＇s disease and other neurological disorders.

Paracrine factors for neurodegenerative disorders:special emphasis on Parkinson's disease

The progressive loss of dopaminergic neurons in the ventral mesencephalon is the main pathological hallmark of Parkinson’s disease（PD）.Drugs currently available only alleviate the principal symptomatic motor-related disturbances and their benefit is counteracted by side effects in the long time.

Antisense therapy:a potential breakthrough in the treatment of neurodegenerative diseases

Neurodegenerative diseases are a group of disorders characterized by the progressive degeneration of neurons in the central or peripheral nervous system.Currently,there is no cure for neurodegenerative diseases and this means a heavy burden for patients and the health system worldwide.Therefore,it is necessary to find new therapeutic approaches,and antisense therapies offer this possibility,having the great advantage of not modifying cellular genome and potentially being safer.Many preclinical and clinical studies aim to test the safety and effectiveness of antisense therapies in the treatment of neurodegenerative diseases.The objective of this review is to summarize the recent advances in the development of these new technologies to treat the most common neurodegenerative diseases,with a focus on those antisense therapies that have already received the approval of the U.S.Food and Drug Administration.

MSCs derived extracellular vesicles as a therapeutic paragon for neurodegenerative disorders:A viewpoint

Neurodegenerative disorders are a vicious woe to the public health and wellness.Uncertainty in their underlying causes,lack of effective biomarkers for their early detection,existence of only supportive therapy,and their ever rising incidence creates an unmatched need for targeted therapies.Mesenchymal Stem Cells(MSCs)have found to be promising candidates for regenerative and remedial therapy in neurodegenerative disorders,however several biological risks and practical issues impede in their translational utility.Deriving from MSCs are certain Extracellular Vesicles(EVs),which aid in the paracrine action of MSCs and have lately gained the scientific interest for their implacability in diverse set ups.Their cargo is of utmost importance and is being explored in various different diseases like heart diseases,neuronal diseases,respiratory diseases and hepatic diseases.They thereby hold the position of a likely prospective remedial candidate for therapy against neurodegenerative disorders.

New insights into the functions of Ptd Ins(3,5)P_2 in the pathogenisis of neurodegenerative disorders

The membrane trafficking systems in brain play an important role in the regulation of neuronal processes,such as morphology,neuronal survival and synaptic plasticity.It has been suggested that the phosphatidylinositols（PIs）located on endolysosomal membranes play a key role in controlling this trafficking systems.

Emergence of taurine as a therapeutic agent for neurological disorders

Taurine is a sulfur-containing,semi-essential amino acid that occurs naturally in the body.It alternates between inflammation and oxidative stress-mediated injury in various disease models.As part of its limiting functions,taurine also modulates endoplasmic reticulum stress,Ca^(2+)homeostasis,and neuronal activity at the molecular level.Taurine effectively protects against a number of neurological disorders,including stro ke,epilepsy,cerebral ischemia,memory dysfunction,and spinal cord injury.Although various therapies are available,effective management of these disorders remains a global challenge.Approximately 30 million people are affected worldwide.The design of taurine fo rmation co uld lead to potential drugs/supplements for the health maintenance and treatment of central nervous system disorders.The general neuroprotective effects of taurine and the various possible underlying mechanisms are discussed in this review.This article is a good resource for understanding the general effects of taurine on various diseases.Given the strong evidence for the neuropharmacological efficacy of taurine in various experimental paradigms,it is concluded that this molecule should be considered and further investigated as a potential candidate for neurotherapeutics,with emphasis on mechanism and clinical studies to determine efficacy.

The Role of Glutamate Dehydrogenase Activity in Development of Neurodegenerative Disorders

The specific role of Glutamate dehydrogenase (GLDH) in the brain is not yet clear, but it is an important enzyme in protein degradation as well as a metabolism regulator of glutamate as a neurotransmitter. The enzyme probably provides crucial protection for postsynaptic membranes against the neurotoxic effects of glutamate neurotransmitters. In men, GLDH activity declines almost evenly through the ages;in women, it declines faster in the first five decades. In the years of menopause, GLDH activity declines slower. The diminished GLDH activities in leukocytes and in the brain vary considerably, but they are parallel with the progress of neurodegenerative diseases. The GLDH activity is partly deficient in the brain, particularly in the leukocytes of patients with heterogeneous neurological disorders and degeneration of multiple neuronal systems. We found a statistically significant difference of GLDH activity in the cerebrospinal fluid in patients with neurological diseases and unexpected in patients with degenerative and inflammatory disorders. The decrease in GLDH activity in the cerebrospinal fluid of patients with neurodegenerative disorders may be one of the reasons for the neuro-excito-toxic glutamate effect. Defining the GLDH activity in leukocytes is at the moment the sole experimental method. The second one could be the measurement in cerebrospinal fluid. The results suggest a possibility to regulate glutamate level in human brain through activation of GLDH.

Role of copper in central nervous system physiology and pathology

Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central nervous system.Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B,Menkes disease and Wilson’s disease,respectively,and also in multifactorial neurological disorders such as Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and multiple sclerosis.This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology,reports about unbalances in copper levels and/or distribution under disease,describes relevant animal models for human disorders where copper metabolism genes are dysregulated,and discusses relevant therapeutic approaches modulating copper availability.Overall,alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.

Potential role and therapeutic implications of glutathione peroxidase 4 in the treatment of Alzheimer's disease

Alzheimer's disease is an age-related neurodegenerative disorder with a complex and incompletely understood pathogenesis. Despite extensive research, a cure for Alzheimer's disease has not yet been found. Oxidative stress mediates excessive oxidative responses, and its involvement in Alzheimer's disease pathogenesis as a primary or secondary pathological event is widely accepted. As a member of the selenium-containing antioxidant enzyme family, glutathione peroxidase 4 reduces esterified phospholipid hydroperoxides to maintain cellular redox homeostasis. With the discovery of ferroptosis, the central role of glutathione peroxidase 4 in anti-lipid peroxidation in several diseases, including Alzheimer's disease, has received widespread attention. Increasing evidence suggests that glutathione peroxidase 4 expression is inhibited in the Alzheimer's disease brain, resulting in oxidative stress, inflammation, ferroptosis, and apoptosis, which are closely associated with pathological damage in Alzheimer's disease. Several therapeutic approaches, such as small molecule drugs, natural plant products, and non-pharmacological treatments, ameliorate pathological damage and cognitive function in Alzheimer's disease by promoting glutathione peroxidase 4 expression and enhancing glutathione peroxidase 4 activity. Therefore, glutathione peroxidase 4 upregulation may be a promising strategy for the treatment of Alzheimer's disease. This review provides an overview of the gene structure, biological functions, and regulatory mechanisms of glutathione peroxidase 4, a discussion on the important role of glutathione peroxidase 4 in pathological events closely related to Alzheimer's disease, and a summary of the advances in small-molecule drugs, natural plant products, and non-pharmacological therapies targeting glutathione peroxidase 4 for the treatment of Alzheimer's disease. Most prior studies on this subject used animal models, and relevant clinical studies are lacking. Future clinical trials are required to validate the therapeutic effects of strategies targeting glutathione peroxidase 4 in the treatment of Alzheimer's disease.

Lipid droplets in the nervous system:involvement in cell metabolic homeostasis

Lipid droplets serve as primary storage organelles for neutral lipids in neurons,glial cells,and other cells in the nervous system.Lipid droplet formation begins with the synthesis of neutral lipids in the endoplasmic reticulum.Previously,lipid droplets were recognized for their role in maintaining lipid metabolism and energy homeostasis;however,recent research has shown that lipid droplets are highly adaptive organelles with diverse functions in the nervous system.In addition to their role in regulating cell metabolism,lipid droplets play a protective role in various cellular stress responses.Furthermore,lipid droplets exhibit specific functions in neurons and glial cells.Dysregulation of lipid droplet formation leads to cellular dysfunction,metabolic abnormalities,and nervous system diseases.This review aims to provide an overview of the role of lipid droplets in the nervous system,covering topics such as biogenesis,cellular specificity,and functions.Additionally,it will explore the association between lipid droplets and neurodegenerative disorders.Understanding the involvement of lipid droplets in cell metabolic homeostasis related to the nervous system is crucial to determine the underlying causes and in exploring potential therapeutic approaches for these diseases.

Agomelatine:a potential novel approach for the treatment of memory disorder in neurodegenerative disease

Agomelatine is a selective agonist of melatonin receptor 1A/melatonin receptor 1B(MT/MT)and antagonist of 5-hydroxytryptamine 2C receptors.It is used clinically to treat major depressive episodes in adults.The pro-chronobiological activity of agomelatine reconstructs sleep-wake rhythms and normalizes circadian disturbances via its agonistic effect of melatonin receptor 1A/melatonin receptor 1B,which work simultaneously to counteract depression and anxiety disorder.Moreover,by antagonizing neocortical postsynaptic 5-hydroxytryptamine 2C receptors,agomelatine enhances the release of dopamine and noradrenaline in the prefrontal cortex,increases the activity of dopamine and noradrenaline,and thereby reduces depression and anxiety disorder.The combination of these two effects means that agomelatine exhibits a unique pharmacological role in the treatment of depression,anxiety,and disturbance of the circadian rhythm.Emotion and sleep are closely related to memory and cognitive function.Memory disorder is defined as any forms of memory abnormality,which is typically evident in a broad range of neurodegenerative diseases,including Alzheimer’s disease.Memory impairment and cognitive impairment are common symptoms of neurodegenerative and psychiatric diseases.Therefore,whether agomelatine can improve memory and cognitive behaviors if used for alleviating depression and circadian-rhythm sleep disorders has become a research“hotspot”.This review presents the latest findings on the effects of agomelatine in the treatment of psychologic and circadian-rhythm sleep disorders in clinical trials and animal experiments.Our review evaluates recent studies on treatment of memory impairment and cognitive impairment in neurodegenerative and psychiatric diseases.

Stem cells:a promising candidate to treat neurological disorders

Neurologic impairments are usually irreversible as a result of limited regeneration in the central nervous system.Therefore,based on the regenerative capacity of stem cells,transplantation therapies of various stem cells have been tested in basic research and preclinical trials,and some have shown great prospects.This manuscript overviews the cellular and molecular characteristics of embryonic stem cells,induced pluripotent stem cells,neural stem cells,retinal stem/progenitor cells,mesenchymal stem/stromal cells,and their derivatives in vivo and in vitro as sources for regenerative therapy.These cells have all been considered as candidates to treat several major neurological disorders and diseases,owing to their self-renewal capacity,multi-directional differentiation,neurotrophic properties,and immune modulation effects.We also review representative basic research and recent clinical trials using stem cells for neurodegenerative diseases,including Parkinson＇s disease,Alzheimer＇s disease,and age-related macular degeneration,as well as traumatic brain injury and glioblastoma.In spite of a few unsuccessful cases,risks of tumorigenicity,and ethical concerns,most results of animal experiments and clinical trials demonstrate efficacious therapeutic effects of stem cells in the treatment of nervous system disease.In summary,these emerging findings in regenerative medicine are likely to contribute to breakthroughs in the treatment of neurological disorders.Thus,stem cells are a promising candidate for the treatment of nervous system diseases.