Models Of Neurodegenerative Diseases Research Articles

Contribution of intraocular pressure‐dependent and pressure‐independent glaucoma models to neuroprotection

AbstractGlaucoma is considered a heterogeneous group of degenerative optic neuropathies characterized mainly by an ongoing loss of retinal ganglion cells (RGCs) which causes progressive deterioration of the visual field and irreversible blindness. The aetiology and pathophysiology of glaucoma are not known in detail and are a matter of debate. Although the most significant risk factor in the development and progression of glaucoma correlates with elevated intraocular pressure (IOP), at present the only treatment available to prevent or delay its development is to reduce IOP by medication or surgery to slow its detrimental effects. But reducing IOP alone does not stop the progression of the disease. Therefore, IOP may not be the only motive for glaucomatous retinopathy and optic neuropathy, and there could be other hidden mechanisms contributing to the loss of RGCs.A suitable animal model of neurodegenerative disease, such as glaucoma, should be easy to induce and reproduce, feasible and predictable, and allow detection and quantification at the biochemical, morphological and functional levels of the induced pathological changes. However, no model emulates all aspects of a pathology such as glaucoma, which is likely to have more than one aetiology and manifest itself through different pathological mechanisms. Hence, the interest and need to establish and use different experimental models in rodents to improve our understanding of the pathophysiology of glaucoma and to investigate possible neuroprotective agents. In general, experimental models of glaucoma established in rodents involve a transient or chronic increase in IOP above normal values, which allows us to study the pathological changes associated with ocular hypertension. However, elevated IOP may not be the only cause of glaucomatous retinopathy and optic neuropathy, hence the need for models that do not involve an increase in intraocular pressure to deal with specific issues of the evolution of this pathology, such as optic nerve injury, retinal ischaemia/reperfusion, intravitreal injection of excitatory amino acids or endothelin‐induced optic neuropathy.Results obtained in different experimental models of glaucoma mimicking ocular hypertension or optic nerve damage have confirmed the existence of morphofunctional differences in the time course of RGC loss, both between different types of RGCs and between different lesions. As well as the effects on other retinal cell populations. In this regard, in the outer retina, there is a significant contrast between damage caused by ocular hypertension and optic nerve injury. Both axotomy and ocular hypertension induce a selective loss of RGCs, but ocular hypertension also promotes a loss of photoreceptors.Thanks to the different glaucoma models studied, the findings obtained have contributed to improving our knowledge of glaucomatous pathology and to the development of future neuroprotective therapies.

Translational Inhibition of Multiple Neurotoxic Proteins Leads to Improved Cognition in Alzheimer’s Disease

AbstractBackgroundOverexpression of neurotoxic proteins drives downstream events that dysregulate axonal transport, lead to inflammation, nerve cell death, and loss of function. By inhibiting the translation of amyloid precursor protein, tau and alpha‐synuclein, our drug restored axonal transport, lowered inflammation, and protected nerve cells from dying in animal models. Buntanetap’s reversal of the toxic cascade leading to nerve cell death did preserve and/or restore full function in 7 different animal models of neurodegenerative diseases including Alzheimer’s disease (AD) and Parkinson’s disease (PD).MethodIn a double blind, placebo controlled Phase2a study, early AD patients were randomized into 80mg Buntanetap (n = 10) or placebo (n = 5) QD for 25±2 days. We evaluated the safety, pharmacokinetics of Buntanetap, biomarkers, and its efficacy.ResultIn clinical trials, Buntanetap was safe in over 200 subjects, both healthy volunteers and AD/PD patients. In our recent double‐blind, placebo controlled Phase2a study, patients randomized to either 80mg QD Buntanetap or placebo we measured biomarkers in AD patients and showed that Buntanetap can lower neurotoxic proteins, improve axonal integrity and synaptic function, and lower inflammation. Buntanetap has also improved AD patients’ cognitive functions as measured by ADASCog11 and WAIS coding test after 25±2 days treatment.ConclusionThese encouraging data support our further development of Buntanetap as a potential treatment for Alzheimer’s disease. We are planning three double‐blind, placebo‐controlled studies, a short 3‐month dose‐finding trial and two long‐term 12‐ and 18‐month trials in early and moderate AD patients.

Translational Inhibition of Multiple Neurotoxic Proteins Leads to Improved Motor Function in Parkinson’s Disease

AbstractBackgroundParkinson’s disease (PD) is a neurodegenerative disorder that affects predominately dopaminergic neurons in substantia nigra. Although alpha‐synuclein (αSYN) is the main component of Lewy bodies, TDP‐43, Aβ and tau are also detected in PD. Buntanetap has been shown to inhibit the translation of multiple neurotoxic proteins such as amyloid precursor protein, tau and alpha‐synuclein. It been shown in animal models to restore axonal transport, lower inflammation and protect nerve cells from dying. By reversing the toxic cascade leading to nerve cell death, Buntanetap preserves and restores full function in 7 different animal models of neurodegenerative diseases including PD.MethodIn our double‐blind, placebo‐controlled, dose‐finding Phase 2a trial, 5 different doses of Buntanetap (5mg, 10mg, 20mg, 40mg and 80mg QD) were tested compared to control after25±2 days treatment. Buntanetap’s safety, pharmacokinetics, biomarkers and efficacy were evaluated.ResultIn clinical trials, Buntanetap was safe in over 200 subjects, both in healthy volunteers and in AD/PD patient. In PD patients, Buntanetap lowers neurotoxic proteins, improves axonal integrity and synaptic function, and lowers inflammation. Buntanetap improves PD patients’ mobility shown by MDS‐UPDRS and WAIS coding test after 25±2 days treatment. Of the 5 different doses, 10 & 20mg Buntanetap QD showed the best clinical outcomes.ConclusionThese data supported us getting regulatory approval to develop next stage pivotal studies in larger population and for longer durations. The FDA consented us to move the development into two phase 3 clinical studies – one in early and one in advanced PD. Our first pivotal trial intends to treat 450 early PD patients at 1:1:1 ration for 10mg, 20mg Buntanetap QD or placebo for 6 months duration.

Relevance of the pre‐clinical models in TBI

AbstractIn the absence of any effective translation from preclinical models to clinical application, what has been achieved by laboratory models of TBI? Analysis and assimilation of results from preclinical TBI studies is confounded by the heterogeneity of the models and the TBI paradigms employed. Variance in animal, injury location, severity, number, frequency, age of animal at injury and age of animal at analyses, not to mention the research focus of the investigators themselves, all contribute to the difficulties in data integration and interpretation. Nonetheless, preclinical TBI research has identified areas of focus and enabled creation of timelines of TBI pathobiology. Ultimately, validation of any potential therapeutic targets will require exploitation of the heterogeneity of preclinical models in order to facilitate clinical translation, given the heterogeneity of the patient population.In the course of modeling TBI paradigms in (primarily) mouse models, the failure of recapitulation of TBI‐dependent neurodegenerative pathology representing AD, PD, ALS etc. has prompted the use of mouse models of neurodegenerative disease, expressing genetic risk factors or humanized for proteins implicated in human neurodegenerative diseases, in efforts to understand how TBI can exacerbate or even precipitate the neurodegenerative pathobiology. These investigations have generated many interesting observations, not always easily consolidated into any clear pathogenic mechanism, but some overarching themes have emerged. Some of the published TBI approaches, and findings, will be reviewed, and knowledge gaps and future directions will be discussed.

New models of Parkinson's like neuroinflammation in human microglia clone 3: Activation profiles induced by INF-γ plus high glucose and mitochondrial inhibitors.

Microglia activation and neuroinflammation have been extensively studied in murine models of neurodegenerative diseases; however, to overcome the genetic differences between species, a human cell model of microglia able to recapitulate the activation profiles described in patients is needed. Here we developed human models of Parkinson's like neuroinflammation by using the human microglia clone 3 (HMC3) cells, whose activation profile in response to classic inflammatory stimuli has been controversial and reported only at mRNA levels so far. In fact, we showed the increased expression of the pro-inflammatory markers iNOS, Caspase 1, IL-1β, in response to IFN-γ plus high glucose, a non-specific disease stimulus that emphasized the dynamic polarization and heterogenicity of the microglial population. More specifically, we demonstrated the polarization of HMC3 cells through the upregulation of iNOS expression and nitrite production in response to the Parkinson's like stimuli, 6-hydroxidopamine (6-OHDA) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the latter depending on the NF-κB pathway. Furthermore, we identified inflammatory mediators that promote the pro-inflammatory activation of human microglia as function of different pathways that can simulate the phenotypic transition according to the stage of the pathology. In conclusion, we established and characterized different systems of HMC3 cells activation as in vitro models of Parkinson's like neuroinflammation.

3-Dimensional Immunostaining and Automated Deep-Learning Based Analysis of Nerve Degeneration

Multiple sclerosis (MS) is an autoimmune and neurodegenerative disease driven by inflammation and demyelination in the brain, spinal cord, and optic nerve. Optic neuritis, characterized by inflammation and demyelination of the optic nerve, is a symptom in many patients with MS. The optic nerve is the highway for visual information transmitted from the retina to the brain. It contains axons from the retinal ganglion cells (RGCs) that reside in the retina, myelin forming oligodendrocytes and resident microglia and astrocytes. Inflammation, demyelination, and axonal degeneration are also present in the optic nerve of mice subjected to experimental autoimmune encephalomyelitis (EAE), a preclinical mouse model of MS. Monitoring the optic nerve in EAE is a useful strategy to study the presentation and progression of pathology in the visual system; however, current approaches have relied on sectioning, staining and manual quantification. Further, information regarding the spatial load of lesions and inflammation is dependent on the area of sectioning. To better characterize cellular pathology in the EAE model, we employed a tissue clearing and 3D immunolabelling and imaging protocol to observe patterns of immune cell infiltration and activation throughout the optic nerve. Increased density of TOPRO staining for nuclei captured immune cell infiltration and Iba1 immunostaining was employed to monitor microglia and macrophages. Axonal degeneration was monitored by neurofilament immunolabelling to reveal axonal swellings throughout the optic nerve. In parallel, we developed a convolutional neural network with a UNet architecture (CNN-UNet) called BlebNet for automated identification and quantification of axonal swellings in whole mount optic nerves. Together this constitutes a toolkit for 3-dimensional immunostaining to monitor general optic nerve pathology and fast automated quantification of axonal defects that could also be adapted to monitor axonal degeneration and inflammation in other neurodegenerative disease models.

Mapping meningeal vasculature in non-human primates

Background. The blood-brain barrier has been the focus of most prior work examining intracranial vasculature in the context of various brain diseases.1 Recently, meningeal vasculature has become more widely recognized as a key contributor to brain clearance and its immune function.2 Meninges are highly vascularized and complex tissue. Vessels of the outer dural layer comprise an extensive, parallel intracranial vascular bed, which lies outside the brain and subarachnoid space. In addition to the blood vasculature, meninges harbor lymphatic channels that potentially provide extra capacity for clearance of proteinaceous fluid and immune cell trafficking. Most of our knowledge of the meningeal vasculature, including lymphatics, comes from rodent models. Rodent meninges are readily available, small, thin and optically transparent. These characteristics permit imaging in whole-mount flat preparations.3 Technical barriers, however, remain high for imaging studies of the meninges of larger mammals. This is especially true for primates, and ultimately humans. Non-human primate (NHP) and human dura is large, thick and opaque, with a high content of connective tissue. These characteristics limit options for routine high-resolution imaging and leave unanswered questions about the architecture of blood and lymphatic vessels in primate dura. So far, the presence of lymphatic vessels in primates has been demonstrated by non-invasive techniques like magnetic resonance imaging (MRI) or on sections of paraffin-embedded specimens. Neither of the techniques fully addresses spatial and phenotypical features of the vascular networks. In our work, we provide solutions for these technical barriers using new clearing and imaging protocols to successfully visualize blood and lymphatic vessels in NPH dura in their entirety.
 Methods. Here we used novel approaches to tissue clearing and resonance scanning confocal imaging of large areas with sickness over 1000 M.
 Results. Our approach revealed extensive and dense vascular networks in NHP dura probed with vascular marker CD31 (Figure 1). Image clarity and resolution is sufficient for visualization of the smallest vessels. In the dura, blood vessels are mostly represented by veins. Vascular networks can be further analyzed with semi-automated tracing and quantitative metrics in 3D space. We showed that lymphatic vessels in NPH dura are located similarly to that in rodents: in the area of the superior sagittal sinus (SSS) and along the middle meningeal artery (MMA). They are also present in the major dural fold, tentorium cerebelli, which is underdeveloped in rodents. Unlike previously described in mice, these vessels are negative for LYVE-1 lymphatic marker but strongly positive for podoplanin. In the area of SSS, there is a large plexus of branching irregular blind-ended sacs with a wide range of diameters. Vessels in the MMA region have a different appearance. Two vessels always run along the veins flanking MMA that follow the artery branching. Our protocol also permits imaging of the extracellular matrix and the cells that reside in the dural environment.
 Conclusions. We developed clearing, mounting and imaging protocols that permitted panoramic fluorescence-based microscopy of NPH dura. These new techniques are directly applicable to primate models of neurodegenerative diseases with a focus on the complex interplay between meningeal arteries, veins, and lymphatics.

Mitochondrial dysfunction of induced pluripotent stem cells-based neurodegenerative disease modeling and therapeutic strategy.

Neurodegenerative diseases (NDDs) are disorders in which neurons are lost owing to various factors, resulting in a series of dysfunctions. Their rising prevalence and irreversibility have brought physical pain to patients and economic pressure to both individuals and society. However, the pathogenesis of NDDs has not yet been fully elucidated, hampering the use of precise medication. Induced pluripotent stem cell (IPSC) modeling provides a new method for drug discovery, and exploring the early pathological mechanisms including mitochondrial dysfunction, which is not only an early but a prominent pathological feature of NDDs. In this review, we summarize the iPSC modeling approach of Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis, as well as outline typical mitochondrial dysfunction and recapitulate corresponding therapeutic strategies.

Synaptic Loss in Frontotemporal Dementia Revealed by [11 C]UCB-J Positron Emission Tomography.

Synaptic loss is an early feature of neurodegenerative disease models, and is severe in post mortem clinical studies, including frontotemporal dementia. Positron emission tomography (PET) with radiotracers that bind to synaptic vesicle glycoprotein 2A enables quantification of synaptic density in vivo. This study used [11 C]UCB-J PET in participants with behavioral variant frontotemporal dementia (bvFTD), testing the hypothesis that synaptic loss is severe and related to clinical severity. Eleven participants with clinically probable bvFTD and 25 age- and sex-matched healthy controls were included. Participants underwent dynamic [11 C]UCB-J PET, structural magnetic resonance imaging, and a neuropsychological battery, including the revised Addenbrooke Cognitive Examination, and INECO frontal screening. General linear models compared [11 C]UCB-J binding potential maps and gray matter volume between groups, and assessed associations between synaptic density and clinical severity in patients. Analyses were also performed using partial volume corrected [11 C]UCB-J binding potential from regions of interest (ROIs). Patients with bvFTD showed severe synaptic loss compared to controls. [11 C]UCB-J binding was reduced bilaterally in medial and dorsolateral frontal regions, inferior frontal gyri, anterior and posterior cingulate gyrus, insular cortex, and medial temporal lobe. Synaptic loss in the frontal and cingulate regions correlated significantly with cognitive impairments. Synaptic loss was more severe than atrophy. Results from ROI-based analyses mirrored the voxelwise results. In accordance with preclinical models, and human postmortem evidence, there is widespread frontotemporal loss of synapses in symptomatic bvFTD, in proportion to severity. [11 C]UCB-J PET could support translational studies and experimental medicine strategies for new disease-modifying treatments for neurodegeneration. ANN NEUROL 2023;93:142-154.

Apelin/APJ system: an emerging therapeutic target for neurological diseases.

Apelin, an endogenous ligand for the G protein-coupled receptor APJ, is extensively expressed in various systems, especially the nervous system. This article reviews the role of apelin/APJ system in neurological diseases. In detail, apelin/APJ system can relieve acute brain injury including subarachnoid hemorrhage, traumatic brain injury, and ischemic stroke. Also, apelin/APJ system has therapeutic effects on chronic neurodegenerative disease models, involving the regulation of neurotrophic factors, neuroendocrine, oxidative stress, neuroinflammation, neuronal apoptosis, and autophagy. In addition, through different routes of administration, apelin/APJ system has a biphasic effect on depression, epilepsy, and pain. However, apelin/APJ system exacerbates the proliferation and invasion of glioblastoma. Thus, apelin/APJ system is expected to be a therapeutic target for the treatment of nervous system diseases.

Immuno(T)herapy for age-related diseases.

During the last decade, the stimulation of T-cell function by the blockage of immunosuppressive checkpoints has experienced an outstanding impact in the treatment of cancer. Development of the chimeric antigen receptor T-cell technology has also emerged as a powerful alternative for patients suffering from oncological processes, especially those affected by hematological neoplasms. Recent evidence suggest that the use of immunotherapy could be extended to non-oncological diseases and could be especially relevant for age-associated disorders, opening exciting therapeutic options for a wide range of diseases of the elderly. Here we comment on the emergence of T-cell-based immunotherapies as feasible approaches that could revolutionize the future of GeroScience.

Folium Hibisci Mutabilis extract, a potent autophagy enhancer, exhibits neuroprotective properties in multiple models of neurodegenerative diseases

BackgroundProtein aggregates are considered key pathological features in neurodegenerative diseases (NDs). The induction of autophagy can effectively promote the clearance of ND-related misfolded proteins. ObjectiveIn this study, we aimed to screen natural autophagy enhancers from traditional Chinese medicines (TCMs) presenting potent neuroprotective potential in multiple ND models. MethodsThe autophagy enhancers were broadly screened in our established herbal extract library using the transgenic Caenorhabditis elegans (C. elegans) DA2123 strain. The neuroprotective effects of the identified autophagy enhancers were evaluated in multiple C. elegans ND models by measuring Aβ-, Tau-, α-synuclein-, and polyQ40-induced pathologies. In addition, PC-12 cells and 3 × Tg-AD mice were employed to further validate the neuroprotective ability of the identified autophagy enhancers, both in vitro and in vivo. Furthermore, RNAi bacteria and autophagy inhibitors were used to evaluate whether the observed effects of the identified autophagy enhancers were mediated by the autophagy-activated pathway. ResultsThe ethanol extract of Folium Hibisci Mutabilis (FHME) was found to significantly increase GFP::LGG-1-positive puncta in the DA2123 worms. FHME treatment markedly inhibited Aβ, α-synuclein, and polyQ40, as well as prolonging the lifespan and improving the behaviors of C. elegans, while siRNA targeting four key autophagy genes partly abrogated the protective roles of FHME in C. elegans. Additionally, FHME decreased the expression of AD-related proteins and restored cell viability in PC-12 cells, which were canceled by cotreatment with 3-methyladenine (3-MA) or bafilomycin A1 (Baf). Moreover, FHME ameliorated AD-like cognitive impairment and pathology, as well as activating autophagy in 3 × Tg-AD mice. ConclusionFHME was successfully screened from our natural product library as a potent autophagy enhancer that exhibits a neuroprotective effect in multiple ND models across species through the induction of autophagy. These findings offer a new and reliable strategy for screening autophagy inducers, as well as providing evidence that FHME may serve as a possible therapeutic agent for NDs.

Development of microglia-targeting adeno-associated viral vectors as tools to study microglial behavior in vivo

Here we describe the microglia-targeting adeno-associated viral (AAV) vectors containing a 1.7-kb putative promoter region of microglia/macrophage-specific ionized calcium-binding adaptor molecule 1 (Iba1), along with repeated miRNA target sites for microRNA (miR)-9 and miR-129-2-3p. The 1.7-kb genomic sequence upstream of the start codon in exon 1 of the Iba1 (Aif1) gene, functions as microglia preferential promoter in the striatum and cerebellum. Furthermore, ectopic transgene expression in non-microglial cells is markedly suppressed upon adding two sets of 4-repeated miRNA target sites for miR-9 and miR-129-2-3p, which are expressed exclusively in non-microglial cells and sponged AAV-derived mRNAs. Our vectors transduced ramified microglia in healthy tissues and reactive microglia in lipopolysaccharide-treated mice and a mouse model of neurodegenerative disease. Moreover, live fluorescent imaging allowed the monitoring of microglial motility and intracellular Ca2+ mobilization. Thus, microglia-targeting AAV vectors are valuable for studying microglial pathophysiology and therapies, particularly in the striatum and cerebellum.

Neuroprotective action of α-Klotho against LPS-activated glia conditioned medium in primary neuronal culture

The α-Klotho is an anti-aging protein that, when overexpressed, extends the life span in humans and mice. It has an anti-inflammatory and protective action on renal cells by inhibiting NF-κB activation and production of inflammatory cytokines in response to TNF-α. Furthermore, studies have shown the neuroprotective effect of α-Klotho against neuroinflammation on different conditions, such as aging, animal models of neurodegenerative diseases, and ischemic brain injury. This work aimed to evaluate the effects of α-Klotho protein on primary glial cell culture against the proinflammatory challenge with LPS and how this could interfere with neuronal health. Cortical mixed glial cells and purified astrocytes were pretreated with α- α-Klotho and stimulated with LPS followed by TNFα, IL-1β, IL-6, IFN-γ levels, and NF-κB activity analysis. Conditioned medium from cortical mixed glia culture treated with LPS (glia conditioned medium (GCM) was used to induce neuronal death of primary cortical neuronal culture and evaluate if GCM-KL (medium from glia culture pretreated α-Klotho followed by LPS stimulation) or GCM + LPS in the presence of KL can reverse the effect. LPS treatment in glial cells induced an increase in proinflammatory mediators such as TNF-α, IL-1β, IL-6, and IFN-γ, and activation of astrocyte NF-κB. GCM treated-cortical neuronal culture induced a concentration-dependent neuronal death. Pretreatment with α-Klotho decreased TNF-α and IL-6 production, reverted NF-κB activation, and decreased neuronal death induced by GCM. In addition, KL incubation together with GCM + LPS completely reverts the neuronal toxicity induced by low concentration of GCM-LPS. These data suggest an anti-inflammatory and neuroprotective effect of α-Klotho protein in the CNS. This work demonstrated the therapeutic potential of α-Klotho in pathological processes which involves a neuroinflammatory component.

Neuronal mitochondrial morphology is significantly affected by both fixative and oxygen level during perfusion.

Neurons in the brain have a uniquely polarized structure consisting of multiple dendrites and a single axon generated from a cell body. Interestingly, intracellular mitochondria also show strikingly polarized morphologies along the dendrites and axons: in cortical pyramidal neurons (PNs), dendritic mitochondria have a long and tubular shape, while axonal mitochondria are small and circular. Mitochondria play important roles in each compartment of the neuron by generating adenosine triphosphate (ATP) and buffering calcium, thereby affecting synaptic transmission and neuronal development. In addition, mitochondrial shape, and thereby function, is dynamically altered by environmental stressors such as oxidative stress or in various neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. Although the importance of altered mitochondrial shape has been claimed by multiple studies, methods for studying this stress-sensitive organelle have not been standardized. Here we address pertinent steps that influence mitochondrial morphology during experimental processes. We demonstrate that fixative solutions containing only paraformaldehyde (PFA), or that introduce hypoxic conditions during the procedure, induce dramatic fragmentation of mitochondria both in vitro and in vivo. This disruption was not observed following the use of glutaraldehyde (GA) addition or oxygen supplementation, respectively. Finally, using pre-formed fibril α-synuclein treated neurons, we show fixative choice can alter experimental outcomes. Specifically, α-synuclein-induced mitochondrial remodeling could not be observed with PFA only fixation as fixation itself caused mitochondrial fragmentation. Our study provides optimized methods for examining mitochondrial morphology in neurons and demonstrates that fixation conditions are critical when investigating the underlying cellular mechanisms involving mitochondria in physiological and neurodegenerative disease models.

Zebrafish: A Pharmacological Model for Learning and Memory Research.

Learning and memory are essential to organism survival and are conserved across various species, especially vertebrates. Cognitive studies involving learning and memory require using appropriate model organisms to translate relevant findings to humans. Zebrafish are becoming increasingly popular as one of the animal models for neurodegenerative diseases due to their low maintenance cost, prolific nature and amenability to genetic manipulation. More importantly, zebrafish exhibit a repertoire of neurobehaviors comparable to humans. In this review, we discuss the forms of learning and memory abilities in zebrafish and the tests used to evaluate the neurobehaviors in this species. In addition, the pharmacological studies that used zebrafish as models to screen for the effects of neuroprotective and neurotoxic compounds on cognitive performance will be summarized here. Lastly, we discuss the challenges and perspectives in establishing zebrafish as a robust model for cognitive research involving learning and memory. Zebrafish are becoming an indispensable model in learning and memory research for screening neuroprotective agents against cognitive impairment.

A systematic review of the effect of photobiomodulation on the neuroinflammatory response in animal models of neurodegenerative diseases.

This systematic review examines the effect of photobiomodulation (PBM), the application of red to near infrared light on body tissues, on the neuroinflammatory response and oxidative stress in animal models of neurodegenerative diseases. The research question and search protocol were prospectively registered on the PROSPERO database. Neurodegenerative diseases are becoming evermore prevalent in the ageing populations across theWestern world, with no disease-modifying or neuroprotective treatment options being available. Hence there is a real need for the development of effective treatment options for patients. Inflammatory responses and oxidative stress within the central nervous system have a strong correlation with neuronal cell death. PBM is a non-invasive therapeutic option that has shown efficacy and promising effects inanimal models of neurodegenerative disease; many studies have reported neuroprotection and improved behavioural outcomes. To the best of our knowledge, therehas been no previous study that has reviewed theanti-inflammatory and the antioxidant effect of PBM inthe context of neurodegeneration. This review has examined this relationship in animal models of a range ofneurodegenerative diseases. We found that PBM can effectively reduce glial activation, pro-inflammatory cytokine expression and oxidative stress, whilst increasing anti-inflammatory glial responses and cytokines, and antioxidant capacity. These positive outcomes accompanied the neuroprotection evident after PBM treatment. Our review provides further indication that PBM can be developed intoan effective non-pharmacological intervention for neurodegenerative diseases.

A novel rhesus macaque model of Huntington's disease recapitulates key neuropathological changes along with motor and cognitive decline.

We created a new nonhuman primate model of the genetic neurodegenerative disorder Huntington's disease (HD) by injecting a mixture of recombinant adeno-associated viral vectors, serotypes AAV2 and AAV2.retro, each expressing a fragment of human mutant HTT (mHTT) into the caudate and putamen of adult rhesus macaques. This modeling strategy results in expression of mutant huntingtin protein (mHTT) and aggregate formation in the injected brain regions, as well as dozens of other cortical and subcortical brain regions affected in human HD patients. We queried the disruption of cortico-basal ganglia circuitry for 30 months post-surgery using a variety of behavioral and imaging readouts. Compared to controls, mHTT-treated macaques developed working memory decline and progressive motor impairment. Multimodal imaging revealed circuit-wide white and gray matter degenerative processes in several key brain regions affected in HD. Taken together, we have developed a novel macaque model of HD that may be used to develop disease biomarkers and screen promising therapeutics.

Synthetic OCT Data Generation to Enhance the Performance of Diagnostic Models for Neurodegenerative Diseases.

PurposeOptical coherence tomography (OCT) has recently emerged as a source for powerful biomarkers in neurodegenerative diseases such as multiple sclerosis (MS) and neuromyelitis optica (NMO). The application of machine learning techniques to the analysis of OCT data has enabled automatic extraction of information with potential to aid the timely diagnosis of neurodegenerative diseases. These algorithms require large amounts of labeled data, but few such OCT data sets are available now.MethodsTo address this challenge, here we propose a synthetic data generation method yielding a tailored augmentation of three-dimensional (3D) OCT data and preserving differences between control and disease data. A 3D active shape model is used to produce synthetic retinal layer boundaries, simulating data from healthy controls (HCs) as well as from patients with MS or NMO.ResultsTo evaluate the generated data, retinal thickness maps are extracted and evaluated under a broad range of quality metrics. The results show that the proposed model can generate realistic-appearing synthetic maps. Quantitatively, the image histograms of the synthetic thickness maps agree with the real thickness maps, and the cross-correlations between synthetic and real maps are also high. Finally, we use the generated data as an augmentation technique to train stronger diagnostic models than those using only the real data.ConclusionsThis approach provides valuable data augmentation, which can help overcome key bottlenecks of limited data.Translational RelevanceBy addressing the challenge posed by limited data, the proposed method helps apply machine learning methods to diagnose neurodegenerative diseases from retinal imaging.

Ayurvedic formulations amalaki rasayana and rasa sindoor improve age-associated memory deficits in mice by modulating dendritic spine densities

BackgroundEmerging reports indicate that age-associated cognitive decline begins with the transition from young to middle-aged, and this neurological condition manifests mainly due to the progressive impairment in the adaptive homeostasis process. Moreover, cognitive decline is associated with neurodegenerative changes in older adults. ObjectivePrevious studies have shown that the administration of Ayurvedic formulations restores the homeostatic pathways and ameliorates neurodegeneration in animal models of neurodegenerative diseases. Therefore, we wanted to check whether Ayurvedic formulations can rescue or delay the age-associated cognitive decline in middle-aged mice. Material and methodsWe fed two-month-old mice with amalaki aasayana (AR, 1025 mg/kg per day) or rasa sindoor (RS, 41 mg/kg per day) mixed in a gelatin-based jelly for six months. Mice eating regular chow or blank jelly served as control. Subsequently, we looked at the improvements in the cognitive and behavioural traits of the treated animals. We have also analysed the effect of these formulations on the dendritic processes of neurons, glial activation, and the formation of corpora amylacea. ResultsWe found a significant improvement in episodic, working- and reference-spatiotemporal memory in animals fed on AR or RS. Microscopic analyses revealed a significant increase in the dendritic spine density in the apical dendrites of the hippocampal pyramidal neurons. The treatment, however, did not significantly affect gliosis and corpora amylacea in the brains. ConclusionsBoth AR and RS showed beneficial effects on memory functions of the middle-aged mice, possibly due to their effect on the dendritic spine densities. Our findings provide strong evidence to conclude that formulations AR and RS can prevent or delay the onset of age-associated cognitive decline.