Drosophila neuronal injury model allows for temporal dissection of neurodegenerative events

Neurodegenerative diseases are extremely prevalent in today’s society and,according to the World Health Organization,are currently listed as the third leading cause of death,following cancer and heart disease（Gammon,2014）.The seminal characteristic of neuro-muscular degeneration is the complete disruption of the circuit between the brain,peripheral neuron,and muscle,

Post-COVID-19 persistent olfactory,gustatory,and trigeminal chemosensory disorders:Definitions,mechanisms,and potential treatments

The nose and the oral cavities are the main sites for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)entry into the body.Smell and taste deficits are the most common acute viral manifestations.Persistent smell disorders are the most common and bothersome complications after SARS-CoV-2 infection,lasting for months to years.The mechanisms and treatment of persistent post-coronavirus disease 2019(COVID-19)smell and taste disorders are still challenges.Information sources for the review are PubMed,Centers for Disease Control and Prevention,Ovid Medline,Embase,Scopus,Web of Science,International Prospective Register of Systematic Reviews,Cumulative Index to Nursing and Allied Health Literature,Elton Bryson Stephens Company,Cochrane Effective Practice and Organization of Care,Cooperation in Science and Technology,International Clinical Trials Registry Platform,World Health Organization,Randomized Controlled Trial Number Registry,and MediFind.This review summarizes the up-to-date information about the prevalence,patterns at onset,and prognoses of post-COVID-19 smell and taste disorders,evidence for the neurotropism of SARS-CoV-2 and the overlap between SARSCoV-1,Middle East respiratory syndrome coronavirus,and SARS-CoV-2 in structure,molecular biology,mode of replication,and host pathogenicity,the suggested cellular and molecular mechanisms for these post-COVID19 chemosensory disorders,and the applied pharmacotherapies and interventions as trials to treat these disorders,and the recommendations for future research to improve understanding of predictors and mechanisms of these disorders.These are crucial for hopeful proper treatment strategies.

Intranasal insulin ameliorates neurological impairment after intracerebral hemorrhage in mice

In Alzheimer’s disease and ischemic stroke,intranasal insulin can act as a neuroprotective agent.However,whether intranasal insulin has a neuroprotective effect in intracerebral hemorrhage and its potential mechanisms remain poorly understood.In this study,a mouse model of autologous blood-induced intracerebral hemorrhage was treated with 0.5,1,or 2 IU insulin via intranasal delivery,twice per day,until 24 or 72 hours after surgery.Compared with saline treatment,1 IU intranasal insulin treatment significantly reduced hematoma volume and brain edema after cerebral hemorrhage,decreased blood-brain barrier permeability and neuronal degeneration damage,reduced neurobehavioral deficits,and improved the survival rate of mice.Expression levels of p-AKT and p-GSK3βwere significantly increased in the perihematoma tissues after intranasal insulin therapy.Our findings suggest that intranasal insulin therapy can protect the neurological function of mice after intracerebral hemorrhage through the AKT/GSK3βsignaling pathway.The study was approved by the Ethics Committee of the North Sichuan Medical College of China(approval No.NSMC(A)2019(01))on January 7,2019.

The neuroprotective potential of endoplasmic reticulum chaperones

Diseases of the nervous system are characterized by axon dysfunction,axon degeneration,and neuronal cell death.The roster of neurodegenerative diseases is striking in the selective vulnerability of the affected neuronal populations and the timing of the onset of disease manifestation and functional deficits.

P2X4 receptor participates in autophagy regulation in Parkinson’s disease

Dysfunctional autophagy often occurs during the development of neurodegenerative diseases,such as Parkinson’s disease,Huntington’s disease,and Alzheimer’s disease.The purinergic P2X4 receptor is an ATP-gated ion channel that is widely expressed in the microglia,astrocytes,and neurons of the central and peripheral nervous systems.P2X4R is involved in the regulation of cellular excitability,synaptic transmission,and neuroinflammation.However,the role played by P2X4R in Parkinson’s disease remains poorly understood.Rat models of Parkinson’s disease were established by injecting 6-hydroxydopamine into the substantia nigra pars compacta.P2X4R-targeted small interfering RNA(siRNA)was injected into the same area 1 week before injury induction to inhibit the expression of the P2X4 receptor.The results showed that the inhibition of P2X4 receptor expression in Parkinson’s disease model rats reduced the rotation behavior induced by apomorphine treatment,increased the latency on the rotarod test,and upregulated the expression of tyrosine hydroxylase,brain-derived neurotrophic factor,LC3-II/LC3-I,Beclin-1,and phosphorylated tropomyosin receptor kinase B(TrkB)in brain tissue,while simultaneously reducing p62 levels.These findings suggest that P2X4 receptor activation might inhibit neuronal autophagy through the regulation of the brain-derived neurotrophic factor/TrkB signaling pathway,leading to dopaminergic neuron damage in the substantia nigra and the further inhibition of P2X4 receptor-mediated autophagy.These results indicate that P2X4 receptor might serve as a potential novel target for the treatment of Parkinson’s disease.This study was approved by the Animal Ethics Committee of Affiliated Hospital of Qingdao University(approval No.QYFYWZLL26119)on April 12,2016.

Animal models of amyotrophic lateral sclerosis： a comparison of model validity

Animal models are necessary to investigate the pathogenic features underlying motor neuron degeneration and for therapeutic development in amyotrophic lateral sclerosis（ALS）. Measures of model validity allow for a critical interpretation of results from each model and caution from over-interpretation of experimental models. Face and construct validity refer to the similarity in phenotype and the proposed causal factor to the human disease, respectively. More recently developed models are restricted by limited phenotype characterization, yet new models hold promise for novel disease insights, thus highlighting their importance. In this article, we evaluate the features of face and construct validity of our new zebrafish model of environmentally-induced motor neuron degeneration and discuss this in the context of current environmental and genetic ALS models, including C9 orf72, mutant Cu/Zn superoxide dismutase 1 and TAR DNA-binding protein 43 mouse and zebrafish models. In this mini-review, we discuss the pros and cons to validity criteria in each model. Our zebrafish model of environmentally-induced motor neuron degeneration displays convincing features of face validity with many hallmarks of ALS-like features, and weakness in construct validity. However, the value of this model may lie in its potential to be more representative of the pathogenic features underlying sporadic ALS cases, where environmental factors may be more likely to be involved in disease etiology than single dominant gene mutations. It may be necessary to compare findings between different strains and species modeling specific genes or environmental factors to confirm findings from ALS animal models and tease out arbitrary strain-and overexpression-specific effects.

MicroRNA expression in animal models of amyotrophic lateral sclerosis and potential therapeutic approaches

A review of recent animal models of amyotrophic lateral sclerosis showed a large number of mi RNAs had altered levels of expression in the brain and spinal cord,motor neurons of spinal cord and brainstem,and hypoglossal,facial,and red motor nuclei and were mostly upregulated.Among the mi RNAs found to be upregulated in two of the studies were mi R-21,mi R-155,mi R-125 b,mi R-146 a,mi R-124,mi R-9,and mi R-19 b,while those downregulated in two of the studies included mi R-146 a,mi R-29,mi R-9,and mi R-125 b.A change of direction in mi RNA expression occurred in some tissues when compared(e.g.,mi R-29 b-3 p in cerebellum and spinal cord of wobbler mice at 40 days),or at different disease stages(e.g.,mi R-200 a in spinal cord of SOD1(G93 A)mice at 95 days vs.108 and 112 days).In the animal models,suppression of mi R-129-5 p resulted in increased lifespan,improved muscle strength,reduced neuromuscular junction degeneration,and tended to improve motor neuron survival in the SOD1(G93 A)mouse model.Suppression of mi R-155 was also associated with increased lifespan,while lowering of mi R-29 a tended to improve lifespan in males and increase muscle strength in SOD1(G93 A)mice.Overexpression of members of mi R-17~92 cluster improved motor neuron survival in SOD1(G93 A)mice.Treatment with an artificial mi RNA designed to target h SOD1 increased lifespan and improved muscle strength in SOD1(G93 A)animals.Further studies with animal models of amyotrophic lateral sclerosis are warranted to validate these findings and identify specific mi RNAs whose suppression or directed against h SOD1 results in increased lifespan,improved muscle strength,reduced neuromuscular junction degeneration,and improved motor neuron survival in SOD1(G93 A)animals.

Calcium channel inhibition-mediated axonal stabilization improves axonal regeneration after optic nerve crush

Axonal projections are specialized neuronal compartments and the longest parts of neurons.Axonal degeneration is a common pathological feature in many neurodegenerative disorders,such as Parkinson’s disease,amyotrophic lateral sclerosis,glaucoma,as well as in traumatic lesions of the central nervous system（CNS）,such as spinal cord injury.

Advancements in pathogenesis studies of Rasmussen’s encephalitis

Rasmussen＇s encephalitis （ RE ） , which was first described by Rasmussen in 1958 , is a rare, dispersed, and progressive neurological syndrome that is characterized by focal epilepsy, unilateral inflammation of the cerebral cortex, progressive hemiplegia and cognitive deterioration. The etiology of this syndrome remains under investigation, and it is hypothesized and widely accepted that RE is a T-cell-mediated autoimmune response. However, the antigenic epitopes and mechanisms are still unknown. The pathological characteristics of RE are cortical inflammation, neuronal loss, and gliosis that are confined to one cere-bral hemisphere. Hemispherectomy remains the only cure for the seizures and cognitive deterioration associated with the disease, but this procedure results in inevitable functional loss in the brain. Compared with surgery, immunomodulatory treatments are expected to cause less neurological deficits, but with limited clinical effect.

Molecular targets for modulating the protein translation vital to proteostasis and neuron degeneration in Parkinson’s disease

Parkinson’s disease(PD)is the most common neurodegenerative movement disorder,which is characterized by the progressive loss of dopaminergic neurons in the Substantia Nigra pars compacta concomitant with Lewy body formation in affected brain areas.The detailed pathogenic mechanisms underlying the selective loss of dopaminergic neurons in PD are unclear,and no drugs or treatments have been developed to alleviate progressive dopaminergic neuron degeneration in PD.However,the formation ofα-synuclein-positive protein aggregates in Lewy body has been identified as a common pathological feature of PD,possibly stemming from the consequence of protein misfolding and dysfunctional proteostasis.Proteostasis is the mechanism for maintaining protein homeostasis via modulation of protein translation,enhancement of chaperone capacity and the prompt clearance of misfolded protein by the ubiquitin proteasome system and autophagy.Deregulated protein translation and impaired capacities of chaperone or protein degradation can disturb proteostasis processes,leading to pathological protein aggregation and neurodegeneration in PD.In recent years,multiple molecular targets in the modulation of protein translation vital to proteostasis and dopaminergic neuron degeneration have been identified.The potential pathophysiological and therapeutic significance of these molecular targets to neurodegeneration in PD is highlighted.