scholarly journals Paraquat Inhalation, a Translationally Relevant Route of Exposure: Disposition to the Brain and Male-Specific Olfactory Impairment in Mice

2020 ◽  
Author(s):  
Timothy Anderson ◽  
Alyssa K Merrill ◽  
Matthew L Eckard ◽  
Elena Marvin ◽  
Katherine Conrad ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Olfactory Bulb ◽  
Brain Regions ◽  
Olfactory Discrimination ◽  
Olfactory Impairment ◽  
Route Of Exposure ◽  
Male Specific ◽  
The Brain ◽  
Lung And Kidney

Abstract Epidemiological and experimental studies have associated oral and systemic exposures to the herbicide paraquat (PQ) with Parkinson’s disease. Despite recognition that airborne particles and solutes can be directly translocated to the brain via olfactory neurons, the potential for inhaled PQ to cause olfactory impairment has not been investigated. This study sought to determine if prolonged low-dose inhalation exposure to PQ would lead to disposition to the brain and olfactory impairment, a prodromal feature of Parkinson’s disease. Adult male and female C57BL/6J mice were exposed to PQ aerosols in a whole-body inhalation chamber for 4 h/day, 5 days/week for 4 weeks. Subsets of mice were sacrificed during and after exposure and PQ concentrations in various brain regions (olfactory bulb, striatum, midbrain, and cerebellum) lung, and kidney were quantified via mass spectrometry. Alterations in olfaction were examined using an olfactory discrimination paradigm. PQ inhalation resulted in an appreciable burden in all examined brain regions, with the highest burden observed in the olfactory bulb, consistent with nasal olfactory uptake. PQ was also detected in the lung and kidney, yet PQ levels in all tissues returned to control values within 4 weeks post exposure. PQ inhalation caused persistent male-specific deficits in olfactory discrimination. No effects were observed in females. These data support the importance of route of exposure in determination of safety estimates for neurotoxic pesticides, such as PQ. Accurate estimation of the relationship between exposure and internal dose is critical for risk assessment and public health protection.

scholarly journals Neuroinflammation and protein pathology in Parkinson’s disease dementia

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Antonina Kouli ◽  
Marta Camacho ◽  
Kieren Allinson ◽  
Caroline H. Williams-Gray
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
T Lymphocytes ◽  
Substantia Nigra ◽  
Amyloid Β ◽  
Brain Regions ◽  
Parkinson’S Disease Dementia ◽  
Activated Microglia ◽  
Cell Counts ◽  
The Brain

AbstractParkinson’s disease dementia is neuropathologically characterized by aggregates of α-synuclein (Lewy bodies) in limbic and neocortical areas of the brain with additional involvement of Alzheimer’s disease-type pathology. Whilst immune activation is well-described in Parkinson’s disease (PD), how it links to protein aggregation and its role in PD dementia has not been explored. We hypothesized that neuroinflammatory processes are a critical contributor to the pathology of PDD. To address this hypothesis, we examined 7 brain regions at postmortem from 17 PD patients with no dementia (PDND), 11 patients with PD dementia (PDD), and 14 age and sex-matched neurologically healthy controls. Digital quantification after immunohistochemical staining showed a significant increase in the severity of α-synuclein pathology in the hippocampus, entorhinal and occipitotemporal cortex of PDD compared to PDND cases. In contrast, there was no difference in either tau or amyloid-β pathology between the groups in any of the examined regions. Importantly, we found an increase in activated microglia in the amygdala of demented PD brains compared to controls which correlated significantly with the extent of α-synuclein pathology in this region. Significant infiltration of CD4+ T lymphocytes into the brain parenchyma was commonly observed in PDND and PDD cases compared to controls, in both the substantia nigra and the amygdala. Amongst PDND/PDD cases, CD4+ T cell counts in the amygdala correlated with activated microglia, α-synuclein and tau pathology. Upregulation of the pro-inflammatory cytokine interleukin 1β was also evident in the substantia nigra as well as the frontal cortex in PDND/PDD versus controls with a concomitant upregulation in Toll-like receptor 4 (TLR4) in these regions, as well as the amygdala. The evidence presented in this study show an increased immune response in limbic and cortical brain regions, including increased microglial activation, infiltration of T lymphocytes, upregulation of pro-inflammatory cytokines and TLR gene expression, which has not been previously reported in the postmortem PDD brain.

scholarly journals Microglial exosomes facilitate α-synuclein transmission in Parkinson’s disease

Brain ◽  
2020 ◽  
Vol 143 (5) ◽  
pp. 1476-1497 ◽  
Author(s):  
Min Guo ◽  
Jian Wang ◽  
Yanxin Zhao ◽  
Yiwei Feng ◽  
Sida Han ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Protein Aggregation ◽  
Brain Regions ◽  
Dependent Manner ◽  
Nigrostriatal Pathway ◽  
Stereotaxic Injection ◽  
Promising Therapeutic Target ◽  
The Brain

Abstract Accumulation of neuronal α-synuclein is a prominent feature in Parkinson’s disease. More recently, such abnormal protein aggregation has been reported to spread from cell to cell and exosomes are considered as important mediators. The focus of such research, however, has been primarily in neurons. Given the increasing recognition of the importance of non-cell autonomous-mediated neurotoxicity, it is critical to investigate the contribution of glia to α-synuclein aggregation and spread. Microglia are the primary phagocytes in the brain and have been well-documented as inducers of neuroinflammation. How and to what extent microglia and their exosomes impact α-synuclein pathology has not been well delineated. We report here that when treated with human α-synuclein preformed fibrils, exosomes containing α-synuclein released by microglia are fully capable of inducing protein aggregation in the recipient neurons. Additionally, when combined with microglial proinflammatory cytokines, these exosomes further increased protein aggregation in neurons. Inhibition of exosome synthesis in microglia reduced α-synuclein transmission. The in vivo significance of these exosomes was demonstrated by stereotaxic injection of exosomes isolated from α-synuclein preformed fibrils treated microglia into the mouse striatum. Phosphorylated α-synuclein was observed in multiple brain regions consistent with their neuronal connectivity. These animals also exhibited neurodegeneration in the nigrostriatal pathway in a time-dependent manner. Depleting microglia in vivo dramatically suppressed the transmission of α-synuclein after stereotaxic injection of preformed fibrils. Mechanistically, we report here that α-synuclein preformed fibrils impaired autophagy flux by upregulating PELI1, which in turn, resulted in degradation of LAMP2 in activated microglia. More importantly, by purifying microglia/macrophage derived exosomes in the CSF of Parkinson’s disease patients, we confirmed the presence of α-synuclein oligomer in CD11b+ exosomes, which were able to induce α-synuclein aggregation in neurons, further supporting the translational aspect of this study. Taken together, our study supports the view that microglial exosomes contribute to the progression of α-synuclein pathology and therefore, they may serve as a promising therapeutic target for Parkinson’s disease.

scholarly journals Environmental Enrichment Attenuates Oxidative Stress and Alters Detoxifying Enzymes in an A53T α-Synuclein Transgenic Mouse Model of Parkinson’s Disease

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 928
Author(s):  
Jung Hwa Seo ◽  
Seong-Woong Kang ◽  
Kyungri Kim ◽  
Soohyun Wi ◽  
Jang Woo Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Olfactory Bulb ◽  
Frontal Cortex ◽  
Brain Stem ◽  
Environmental Enrichment ◽  
Brain Regions ◽  
Wild Type ◽  
Detoxifying Enzymes

Although environmental enrichment (EE) is known to reduce oxidative stress in Parkinson’s disease (PD), the metabolic alternations for detoxifying endogenous and xenobiotic compounds according to various brain regions are not fully elucidated yet. This study aimed to further understand the role of EE on detoxifying enzymes, especially those participating in phase I of metabolism, by investigating the levels of enzymes in various brain regions such as the olfactory bulb, brain stem, frontal cortex, and striatum. Eight-month-old transgenic PD mice with the overexpression of human A53T α-synuclein and wild-type mice were randomly allocated to either standard cage condition or EE for 2 months. At 10 months of age, the expression of detoxifying enzymes was evaluated and compared with wild-type of the same age raised in standard cages. EE improved neurobehavioral outcomes such as olfactory and motor function in PD mice. EE-treated mice showed that oxidative stress was attenuated in the olfactory bulb, brain stem, and frontal cortex. EE also reduced apoptosis and induced cell proliferation in the subventricular zone of PD mice. The overexpression of detoxifying enzymes was observed in the olfactory bulb and brain stem of PD mice, which was ameliorated by EE. These findings were not apparent in the other experimental regions. These results suggest the stage of PD pathogenesis may differ according to brain region, and that EE has a protective effect on the PD pathogenesis by decreasing oxidative stress.

scholarly journals The Efficacy of Iron Chelators for Removing Iron from Specific Brain Regions and the Pituitary—Ironing out the Brain

2019 ◽  
Vol 12 (3) ◽  
pp. 138 ◽  
Author(s):  
Robert R. Crichton ◽  
Roberta J. Ward ◽  
Robert C. Hider
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Iron Chelation ◽  
Brain Regions ◽  
Beta Thalassemia ◽  
Excess Iron ◽  
New Class ◽  
Clinical Conditions ◽  
The Brain

Iron chelation therapy, either subcutaneous or orally administered, has been used successfully in various clinical conditions. The removal of excess iron from various tissues, e.g., the liver spleen, heart, and the pituitary, in beta thalassemia patients, has become an essential therapy to prolong life. More recently, the use of deferiprone to chelate iron from various brain regions in Parkinson’s Disease and Friederich’s Ataxia has yielded encouraging results, although the side effects, in <2% of Parkinson’s Disease(PD) patients, have limited its long-term use. A new class of hydroxpyridinones has recently been synthesised, which showed no adverse effects in preliminary trials. A vital question remaining is whether inflammation may influence chelation efficacy, with a recent study suggesting that high levels of inflammation may diminish the ability of the chelator to bind the excess iron.

scholarly journals Systemic α-synuclein injection triggers selective neuronal pathology as seen in patients with Parkinson’s disease

2019 ◽  
Author(s):  
Wei-Li Kuan ◽  
Katherine Stott ◽  
Xiaoling He ◽  
Tobias C. Wood ◽  
Sujeong Yang ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Brain Regions ◽  
Neuronal Populations ◽  
Novel Approach ◽  
Quaternary Structures ◽  
Cellular Pathology ◽  
First Time ◽  
The Brain ◽  
Delivery Approach

AbstractParkinson’s disease (PD) is an α-synucleinopathy characterized by the progressive loss of specific neuronal populations. Here, we develop a novel approach to transvascularly deliver proteins of complex quaternary structures, including α-synuclein preformed fibrils (pff). We show that a single systemic administration of α-synuclein pff triggers pathological transformation of endogenous α-synuclein in non-transgenic rats, which leads to neurodegeneration in discrete brain regions. Specifically, pff-exposed animals displayed a progressive deterioration in gastrointestinal and olfactory functions, which corresponded with the presence of cellular pathology in the central and enteric nervous systems. The α-synuclein pathology generated was both time dependent and region specific. Interestingly, the most significant neuropathological changes were observed in those brain regions affected in the early stages of PD. Our data therefore demonstrate for the first time that a single, transvascular administration of α-synuclein pff can lead to selective regional neuropathology resembling the premotor stage of idiopathic PD. Furthermore, this novel delivery approach could also be used to deliver a range of other pathogenic, as well as therapeutic, protein cargos transvascularly to the brain.

scholarly journals Widespread transneuronal propagation of α-synucleinopathy triggered in olfactory bulb mimics prodromal Parkinson’s disease

2016 ◽  
Vol 213 (9) ◽  
pp. 1759-1778 ◽  
Author(s):  
Nolwen L. Rey ◽  
Jennifer A. Steiner ◽  
Nazia Maroof ◽  
Kelvin C. Luk ◽  
Zachary Madaj ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Mouse Model ◽  
Olfactory Bulb ◽  
Amyloid Fibrils ◽  
Brain Regions ◽  
Neural Pathways ◽  
Wild Type

Parkinson’s disease (PD) is characterized by the progressive appearance of intraneuronal Lewy aggregates, which are primarily composed of misfolded α-synuclein (α-syn). The aggregates are believed to propagate via neural pathways following a stereotypical pattern, starting in the olfactory bulb (OB) and gut. We hypothesized that injection of fibrillar α-syn into the OB of wild-type mice would recreate the sequential progression of Lewy-like pathology, while triggering olfactory deficits. We demonstrate that injected α-syn fibrils recruit endogenous α-syn into pathological aggregates that spread transneuronally over several months, initially in the olfactory network and later in distant brain regions. The seeded inclusions contain posttranslationally modified α-syn that is Thioflavin S positive, indicative of amyloid fibrils. The spreading α-syn pathology induces progressive and specific olfactory deficits. Thus, we demonstrate that propagating α-syn pathology triggered in the OB is functionally detrimental. Collectively, we have created a mouse model of prodromal PD.

scholarly journals Application of Functional Magnetic Resonance Imaging in the Diagnosis of Parkinson’s Disease: A Histogram Analysis

2021 ◽  
Vol 13 ◽  
Author(s):  
Dafa Shi ◽  
Haoran Zhang ◽  
Siyuan Wang ◽  
Guangsong Wang ◽  
Ke Ren
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Feature Selection ◽  
Model Performance ◽  
Area Under The Curve ◽  
Low Frequency ◽  
Brain Regions ◽  
Histogram Analysis ◽  
Validation Set ◽  
The Brain

This study aimed to investigate the value of amplitude of low-frequency fluctuation (ALFF)-based histogram analysis in the diagnosis of Parkinson’s disease (PD) and to investigate the regions of the most important discriminative features and their contribution to classification discrimination. Patients with PD (n = 59) and healthy controls (HCs; n = 41) were identified and divided into a primary set (80 cases, including 48 patients with PD and 32 HCs) and a validation set (20 cases, including 11 patients with PD and nine HCs). The Automated Anatomical Labeling (AAL) 116 atlas was used to extract the histogram features of the regions of interest in the brain. Machine learning methods were used in the primary set for data dimensionality reduction, feature selection, model construction, and model performance evaluation. The model performance was further validated in the validation set. After feature data dimension reduction and feature selection, 23 of a total of 1,276 features were entered in the model. The brain regions of the selected features included the frontal, temporal, parietal, occipital, and limbic lobes, as well as the cerebellum and the thalamus. In the primary set, the area under the curve (AUC) of the model was 0.974, the sensitivity was 93.8%, the specificity was 90.6%, and the accuracy was 93.8%. In the validation set, the AUC, sensitivity, specificity, and accuracy were 0.980, 90.9%, 88.9%, and 90.0%, respectively. ALFF-based histogram analysis can be used to classify patients with PD and HCs and to effectively identify abnormal brain function regions in PD patients.

scholarly journals Deficits in olfactory sensitivity in a mouse model of Parkinson’s disease revealed by plethysmography of odor-evoked sniffing

2020 ◽  
Author(s):  
Michaela E. Johnson ◽  
Liza Bergkvist ◽  
Gabriela Mercado ◽  
Lucas Stetzik ◽  
Lindsay Meyerdirk ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Olfactory Bulb ◽  
Brain Regions ◽  
Detection Sensitivity ◽  
Motor Nucleus ◽  
List Type ◽  
Anterior Olfactory Nucleus ◽  
Odor Detection ◽  
Female Mice

AbstractHyposmia is evident in over 90% of Parkinson’s disease (PD) patients. A characteristic of PD is intraneuronal deposits composed in part of α-synuclein fibrils. Based on the analysis of post-mortem PD patients, Braak and colleagues suggested that early in the disease α-synuclein pathology is present in the dorsal motor nucleus of the vagus, as well as the olfactory bulb and the anterior olfactory nucleus, and then later affects other interconnected brain regions. Here, we bilaterally injected α-synuclein preformed fibrils into the olfactory bulb of wild type male and female mice. Six-months after injection, the anterior olfactory nucleus and the piriform cortex displayed a high α-synuclein pathology load. We evaluated olfactory perceptual function by monitoring odor-evoked sniffing behavior in a plethysmograph at one-, three- and six-months after injection of α-synuclein fibrils. At all-time points, females injected with fibrils exhibited reduced odor detection sensitivity, which was detectable with the semi-automated plethysmography apparatus, but not a buried pellet test. In future studies, this sensitive methodology we used to assess olfactory detection deficits could be used to define how α-synuclein pathology affects other aspects of olfactory perception in PD models and to clarify the neuropathological underpinnings of these deficits.Highlights- α-synuclein pathology spreads through neuronally-connected areas after bilateral injection of preformed fibrils into the olfactory bulb.- A plethysmograph and an olfactometer were used for a semi-automated screen of odor-evoked sniffing as an assay for odor detection sensitivity.- Bilateral olfactory bulb injections of α-synuclein preformed fibrils in female mice led to reduced sensitivity for detecting odors.- The semi-automated plethysmography apparatus was more sensitive at detecting odor detection deficits than the buried pellet test.

scholarly journals Iron Accumulation Is Not Homogenous among Patients with Parkinson’s Disease

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Khashayar Dashtipour ◽  
Manju Liu ◽  
Camellia Kani ◽  
Pejman Dalaie ◽  
Andre Obenaus ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Iron Content ◽  
De Novo ◽  
Brain Regions ◽  
Iron Accumulation ◽  
Loma Linda University ◽  
Neurology Clinic ◽  
The Brain ◽  
Possible Cause

Background. Iron is considered to lead to neurodegeneration and has been hypothesized as a possible cause of Parkinson’s disease (PD). Susceptibility-weighted imaging (SWI) is a powerful tool to measure phase related iron content of brain.Methods. Twelve de novo patients with PD were recruited from the Movement Disorders Clinic, Department of Neurology, Loma Linda University. Twelve age- and sex-matched non-PD subjects were recruited from neurology clinic as controls. Using SWI, the phase related iron content was estimated from different brain regions of interest (ROIs).Results. There was a trend between increasing age and iron accumulation in the globus pallidus and putamen in all subjects. Iron accumulation was not significant in different ROIs in PD patients compared to controls after adjustment for age. Our data revealed heterogeneity of phase values in different brain ROIs among all subjects with an exaggerated trend at SN in PD patients.Conclusions. Our data suggest a nonhomogeneous pattern of iron accumulation in different brain regions among PD patients. Further studies are needed to explore whether this may correlate to the progression of PD. To our knowledge, this is the first study demonstrating the heterogeneity of iron accumulation in the brain, among patients with PD.

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