RESUMEN
Lewy Body Dementias (LBD), including Parkinson's disease dementia and Dementia with Lewy Bodies, are characterized by widespread accumulation of intracellular alpha-Synuclein protein deposits in regions beyond the brainstem, including in the cortex. However, the impact of local pathology in the cortex is unknown. To investigate this, we employed viral overexpression of human alpha-Synuclein protein targeting the mouse prefrontal cortex (PFC). We then used in vivo 2-photon microscopy to image awake head-fixed mice via an implanted chronic cranial window to assess the early consequences of alpha-Synuclein overexpression in the weeks following overexpression. We imaged apical tufts of Layer V pyramidal neurons in the PFC of Thy1-YFP transgenic mice at 1-week intervals from 1 to 2 weeks before and 9 weeks following viral overexpression, allowing analysis of dynamic changes in dendritic spines. We found an increase in the relative dendritic spine density following local overexpression of alpha-Synuclein, beginning at 5 weeks post-injection, and persisting for the remainder of the study. We found that alpha-Synuclein overexpression led to an increased percentage and longevity of newly-persistent spines, without significant changes in the total density of newly formed or eliminated spines. A follow-up study utilizing confocal microscopy revealed that the increased spine density is found in cortical cells within the alpha-Synuclein injection site, but negative for alpha-Synuclein phosphorylation at Serine-129, highlighting the potential for effects of dose and local circuits on spine survival. These findings have important implications for the physiological role and early pathological stages of alpha-Synuclein in the cortex.
Asunto(s)
Espinas Dendríticas , Ratones Transgénicos , Corteza Prefrontal , alfa-Sinucleína , Animales , Humanos , Masculino , Ratones , alfa-Sinucleína/metabolismo , Supervivencia Celular/fisiología , Espinas Dendríticas/metabolismo , Ratones Endogámicos C57BL , Corteza Prefrontal/metabolismo , Corteza Prefrontal/patología , Células Piramidales/metabolismo , Células Piramidales/patologíaRESUMEN
Importance: Finding a reliable diagnostic biomarker for the disorders collectively known as synucleinopathies (Parkinson disease [PD], dementia with Lewy bodies [DLB], multiple system atrophy [MSA], and pure autonomic failure [PAF]) is an urgent unmet need. Immunohistochemical detection of cutaneous phosphorylated α-synuclein may be a sensitive and specific clinical test for the diagnosis of synucleinopathies. Objective: To evaluate the positivity rate of cutaneous α-synuclein deposition in patients with PD, DLB, MSA, and PAF. Design, Setting, and Participants: This blinded, 30-site, cross-sectional study of academic and community-based neurology practices conducted from February 2021 through March 2023 included patients aged 40 to 99 years with a clinical diagnosis of PD, DLB, MSA, or PAF based on clinical consensus criteria and confirmed by an expert review panel and control participants aged 40 to 99 years with no history of examination findings or symptoms suggestive of a synucleinopathy or neurodegenerative disease. All participants completed detailed neurologic examinations and disease-specific questionnaires and underwent skin biopsy for detection of phosphorylated α-synuclein. An expert review panel blinded to pathologic data determined the final participant diagnosis. Exposure: Skin biopsy for detection of phosphorylated α-synuclein. Main Outcomes: Rates of detection of cutaneous α-synuclein in patients with PD, MSA, DLB, and PAF and controls without synucleinopathy. Results: Of 428 enrolled participants, 343 were included in the primary analysis (mean [SD] age, 69.5 [9.1] years; 175 [51.0%] male); 223 met the consensus criteria for a synucleinopathy and 120 met criteria as controls after expert panel review. The proportions of individuals with cutaneous phosphorylated α-synuclein detected by skin biopsy were 92.7% (89 of 96) with PD, 98.2% (54 of 55) with MSA, 96.0% (48 of 50) with DLB, and 100% (22 of 22) with PAF; 3.3% (4 of 120) of controls had cutaneous phosphorylated α-synuclein detected. Conclusions and Relevance: In this cross-sectional study, a high proportion of individuals meeting clinical consensus criteria for PD, DLB, MSA, and PAF had phosphorylated α-synuclein detected by skin biopsy. Further research is needed in unselected clinical populations to externally validate the findings and fully characterize the potential role of skin biopsy detection of phosphorylated α-synuclein in clinical care.
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Piel , Sinucleinopatías , alfa-Sinucleína , Anciano , Femenino , Humanos , Masculino , alfa-Sinucleína/análisis , Biopsia , Estudios Transversales , Enfermedad por Cuerpos de Lewy/diagnóstico , Enfermedad por Cuerpos de Lewy/patología , Atrofia de Múltiples Sistemas/diagnóstico , Atrofia de Múltiples Sistemas/patología , Enfermedad de Parkinson/diagnóstico , Enfermedad de Parkinson/patología , Sinucleinopatías/diagnóstico , Sinucleinopatías/patología , Fosforilación , Piel/química , Piel/patología , Insuficiencia Autonómica Pura/diagnóstico , Insuficiencia Autonómica Pura/patología , Reproducibilidad de los Resultados , Adulto , Persona de Mediana Edad , Anciano de 80 o más Años , Método Simple Ciego , Estudios ProspectivosAsunto(s)
COVID-19/mortalidad , Enfermedad de Parkinson/complicaciones , Distribución por Edad , Anciano , Anciano de 80 o más Años , COVID-19/complicaciones , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Mortalidad , Oportunidad Relativa , Pandemias , Grupos Raciales , Riesgo , SARS-CoV-2 , Distribución por Sexo , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (α-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops α-syn aggregates in DLB and PDD. OBJECTIVE: To investigate the long-term behavioral and cognitive consequences of α-syn pathology in the cortex and characterize pathological spread of α-syn. METHODS: We injected human α-syn pre-formed fibrils into the PFC of wild-type male mice. We then assessed the behavioral and cognitive effects between 12- and 21-months post-injection and characterized the spread of pathological α-syn in cortical, subcortical, and brainstem regions. RESULTS: We report that PFC PFFs: 1) induced α-syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; and 3) increased open field exploration. CONCLUSIONS: This model of cortical-dominant pathology aids in our understanding of how local α-syn aggregation might impact some symptoms in PDD and DLB.
Asunto(s)
Enfermedad de Alzheimer , Demencia , Enfermedad de Parkinson , Humanos , Masculino , Ratones , Animales , alfa-Sinucleína/metabolismo , Enfermedad de Parkinson/patología , Corteza Prefrontal/patologíaRESUMEN
The chloroplast is the site of photosynthesis in higher plants but also functions as the center of synthesis for primary and specialized metabolites including amino acids, fatty acids, starch, and diverse isoprenoids. Mutants that disrupt aspects of chloroplast function represent valuable tools for defining structural and biochemical regulation of the chloroplast and its interplay with whole-plant structure and function. The lutescent1 (l1) and l2 mutants of tomato (Solanum lycopersicum) possess a range of chlorophyll-deficient phenotypes including reduced rates of chlorophyll synthesis during deetiolation and enhanced rates of chlorophyll loss in leaves and fruits as they age, particularly in response to high-light stress and darkness. In addition, the onset of fruit ripening is delayed in lutescent mutants by approximately 1 week although once ripening is initiated they ripen at a normal rate and accumulation of carotenoids is not impaired. The l2 locus was mapped to the long arm of chromosome 10 and positional cloning revealed the existence of a premature stop codon in a chloroplast-targeted zinc metalloprotease of the M50 family that is homologous to the Arabidopsis (Arabidopsis thaliana) gene ETHYLENE-DEPENDENT GRAVITROPISM DEFICIENT AND YELLOW-GREEN1. Screening of tomato germplasm identified two additional l2 mutant alleles. This study suggests a role for the chloroplast in mediating the onset of fruit ripening in tomato and indicates that chromoplast development in fruit does not depend on functional chloroplasts.
Asunto(s)
Cloroplastos/enzimología , Frutas/crecimiento & desarrollo , Sitios Genéticos/genética , Metaloendopeptidasas/metabolismo , Mutación/genética , Solanum lycopersicum/enzimología , Zinc/metabolismo , Alelos , Secuencia de Aminoácidos , Proteínas de Arabidopsis/química , Clorofila/metabolismo , Cloroplastos/efectos de la radiación , Clonación Molecular , Frutas/enzimología , Frutas/efectos de la radiación , Pleiotropía Genética/efectos de la radiación , Luz , Solanum lycopersicum/genética , Solanum lycopersicum/crecimiento & desarrollo , Metaloendopeptidasas/química , Metaloproteasas/química , Datos de Secuencia Molecular , Morfogénesis/efectos de la radiación , Fenotipo , Fotosíntesis/efectos de la radiación , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Tilacoides/metabolismo , Tilacoides/efectos de la radiaciónRESUMEN
Fragile X syndrome (FXS) is the most common inherited form of mental retardation and is caused by transcriptional inactivation of the X-linked fragile X mental retardation 1 (FMR1) gene. FXS is associated with increased density and abnormal morphology of dendritic spines, the postsynaptic sites of the majority of excitatory synapses. To better understand how lack of the FMR1 gene function affects spine development and plasticity, we examined spine formation and elimination of layer 5 pyramidal neurons in the whisker barrel cortex of Fmr1 KO mice with a transcranial two-photon imaging technique. We found that the rates of spine formation and elimination over days to weeks were significantly higher in both young and adult KO mice compared with littermate controls. The heightened spine turnover in KO mice was due to the existence of a larger pool of "short-lived" new spines in KO mice than in controls. Furthermore, we found that the formation of new spines and the elimination of existing ones were less sensitive to modulation by sensory experience in KO mice. These results indicate that the loss of Fmr1 gene function leads to ongoing overproduction of transient spines in the primary somatosensory cortex. The insensitivity of spine formation and elimination to sensory alterations in Fmr1 KO mice suggest that the developing synaptic circuits may not be properly tuned by sensory stimuli in FXS.
Asunto(s)
Espinas Dendríticas/fisiología , Síndrome del Cromosoma X Frágil/fisiopatología , Sinapsis/fisiología , Animales , Espinas Dendríticas/metabolismo , Diagnóstico por Imagen/métodos , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Síndrome del Cromosoma X Frágil/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Fragile X syndrome is caused by the absence of functional fragile X mental retardation protein (FMRP), an RNA binding protein. The molecular mechanism of aberrant protein synthesis in fmr1 KO mice is closely associated with the role of FMRP in mRNA transport, delivery, and local protein synthesis. We show that GFP-labeled Fmr1 and CaMKIIalpha mRNAs undergo decelerated motion at 0-40 min after group I mGluR stimulation, and later recover at 40-60 min. Then we investigate targeting of mRNAs associated with FMRP after neuronal stimulation. We find that FMRP is synthesized closely adjacent to stimulated mGluR5 receptors. Moreover, in WT neurons, CaMKIIalpha mRNA can be delivered and translated in dendritic spines within 10 min in response to group I mGluR stimulation, whereas KO neurons fail to show this response. These data suggest that FMRP can mediate spatial mRNA delivery for local protein synthesis in response to synaptic stimulation.
Asunto(s)
Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Neuronas/metabolismo , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Animales , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/genética , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Células Cultivadas , Dendritas/metabolismo , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Hipocampo/citología , Hibridación Fluorescente in Situ , Cinética , Metoxihidroxifenilglicol/análogos & derivados , Metoxihidroxifenilglicol/farmacología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Microscopía Fluorescente , Neuronas/citología , Neuronas/efectos de los fármacos , Unión Proteica , Transporte de ARN , ARN Mensajero/genética , Receptor del Glutamato Metabotropico 5 , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismo , Factores de TiempoRESUMEN
Terazosin is an α1-adrenergic receptor antagonist that enhances glycolysis and increases cellular ATP by binding to the enzyme phosphoglycerate kinase 1 (PGK1). Recent work has shown that terazosin is protective against motor dysfunction in rodent models of Parkinson's disease (PD) and is associated with slowed motor symptom progression in PD patients. However, PD is also characterized by profound cognitive symptoms. We tested the hypothesis that terazosin protects against cognitive symptoms associated with PD. We report two main results. First, in rodents with ventral tegmental area (VTA) dopamine depletion modeling aspects of PD-related cognitive dysfunction, we found that terazosin preserved cognitive function. Second, we found that after matching for demographics, comorbidities, and disease duration, PD patients newly started on terazosin, alfuzosin, or doxazosin had a lower hazard of being diagnosed with dementia compared to tamsulosin, an α1-adrenergic receptor antagonist that does not enhance glycolysis. Together, these findings suggest that in addition to slowing motor symptom progression, glycolysis-enhancing drugs protect against cognitive symptoms of PD.
RESUMEN
Lewy Body Dementias (LBD), including Parkinson's disease dementia and Dementia with Lewy Bodies, are characterized by widespread accumulation of intracellular alpha-Synuclein protein deposits in regions beyond the brainstem, including in the cortex. Patients with LBDs develop cognitive changes, including abnormalities in executive function, attention, hallucinations, slowed processing, and cognitive fluctuations. The causes of these non-motor symptoms remain unclear; however, accumulation of alpha-Synuclein aggregates in the cortex and subsequent interference of synaptic and cellular function could contribute to psychiatric and cognitive symptoms. It is unknown how the cortex responds to local pathology in the absence of significant secondary effects of alpha-Synuclein pathology in the brainstem. To investigate this, we employed viral overexpression of human alpha-Synuclein protein targeting the mouse prefrontal cortex (PFC). We then used in vivo 2-photon microscopy to image awake head-fixed mice via an implanted chronic cranial window to assess the early consequences of alpha-Synuclein overexpression in the weeks following overexpression. We imaged apical tufts of Layer V pyramidal neurons in the PFC of Thy1-YFP transgenic mice at 1-week intervals from 1-2 weeks before and 9 weeks following viral overexpression, allowing analysis of dynamic changes in dendritic spines. We found an increase in the relative dendritic spine density following local overexpression of alpha-Synuclein, beginning at 5 weeks post-injection, and persisting for the remainder of the study. We found that alpha-Synuclein overexpression led to an increased percentage and longevity of newly-persistent spines, without significant changes in the total density of newly formed or eliminated spines. A follow up study utilizing confocal microscopy revealed that the increased spine density is found in cortical cells within the alpha-Synuclein injection site, but negative for alpha-Synuclein phosphorylation at Serine-129, highlighting the potential for effects of dose and local circuits on spine survival. These findings have important implications for the physiological role and early pathological stages of alpha-Synuclein in the cortex.
RESUMEN
Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (α-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops α-syn aggregates in DLB and PDD. To investigate the consequences of α-syn pathology in the cortex, we injected human α-syn pre-formed fibrils into the PFC of wildtype mice. We report that PFC PFFs: 1) induced α-syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; 3) increased open field exploration; and 4) did not affect susceptibility to an inflammatory challenge. This model of cortical-dominant pathology aids in our understanding of how local α-syn aggregation might impact some symptoms in PDD and DLB.
RESUMEN
Cognitive dysfunction is one of the most prevalent non-motor symptoms in patients with Parkinson's disease (PD). While it tends to worsen in the later stages of disease, it can occur at any time, with 15-20% of patients exhibiting cognitive deficits at diagnosis (Aarsland et al., 2010; Goldman and Sieg, 2020). The characteristic features of cognitive dysfunction include impairment in executive function, visuospatial abilities, and attention, which vary in severity from subtle impairment to overt dementia (Martinez-Horta and Kulisevsky, 2019). To complicate matters, cognitive dysfunction is prone to fluctuate in PD patients, impacting diagnosis and the ability to assess progression and decision-making capacity. The diagnosis of cognitive impairment or dementia has a huge impact on patient independence, quality of life, life expectancy and caregiver burden (Corallo et al., 2017; Lawson et al., 2016; Leroi et al., 2012). It is therefore essential that physicians caring for patients with PD provide education, screening and treatment for this aspect of the disease. In this chapter, we provide a practical guide for the assessment and management of various degrees of cognitive dysfunction in patients with PD by approaching the disease at different stages. We address risk factors for cognitive dysfunction, prevention strategies prior to making the diagnosis, available tools for screening. Lastly, we review aspects of care, management and considerations, including decision-making capacity, that occur after the patient has been diagnosed with cognitive dysfunction or dementia.
Asunto(s)
Disfunción Cognitiva , Demencia , Enfermedad de Parkinson , Disfunción Cognitiva/etiología , Demencia/complicaciones , Humanos , Pruebas Neuropsicológicas , Atención al Paciente/efectos adversos , Calidad de VidaRESUMEN
Neurons emit axons, which form synapses, the fundamental unit of the nervous system. Neuroscientists use genetic anterograde tracing methods to label the synaptic output of specific neuronal subpopulations, but the resulting data sets are too large for manual analysis, and current automated methods have significant limitations in cost and quality. In this paper, we describe a pipeline optimized to identify anterogradely labeled presynaptic boutons in brain tissue sections. Our histologic pipeline labels boutons with high sensitivity and low background. To automatically detect labeled boutons in slide-scanned tissue sections, we developed BoutonNet. This detector uses a two-step approach: an intensity-based method proposes possible boutons, which are checked by a neural network-based confirmation step. BoutonNet was compared to expert annotation on a separate validation data set and achieved a result within human inter-rater variance. This open-source technique will allow quantitative analysis of the fundamental unit of the brain on a whole-brain scale.
Asunto(s)
Terminales Presinápticos , Sinapsis , Axones , Encéfalo , Humanos , Neuronas , Terminales Presinápticos/fisiología , Sinapsis/fisiologíaRESUMEN
The decision to move is influenced by sensory, attentional, and motivational cues. One such cue is the quality of the tactile input, with noxious or unpleasant sensations causing an animal to move away from the cue. Processing of painful and unpleasant sensation in the cortex involves multiple brain regions, although the specific role of the brain areas involved in voluntary, rather than reflexive movement away from unpleasant stimuli is not well understood. Here, we focused on the medial subdivision of secondary motor cortex, which is proposed to link sensory and contextual cues to motor action, and tested its role in controlling voluntary movement in the context of an aversive tactile cue. We designed a novel, 3D-printed tactile platform consisting of innocuous (grid) and mildly noxious (spiked) surfaces (50:50 % of total area), which enabled monitoring neuronal activity in the medial frontal cortex by two-photon imaging during a sensory preference task in head-fixed mice. We found that freely moving mice spent significantly less time on a spiked-surface, and that this preference was eliminated by administration of a local anesthetic. At the neuronal level, individual neurons were differentially modulated specific to the tactile surface encountered. At the population level, the neuronal activity was analyzed in relation to the events where mice chose to "stop-on" or "go-from" a specific tactile surface and when they "switched" surfaces without stopping. Notably, each of these three scenarios showed population activity that differed significantly between the grid and spiked tactile surfaces. Collectively, these data provide evidence that tactile quality is encoded within medial frontal cortex. The task pioneered in this study provides a valuable tool to better evaluate mouse models of nociception and pain, using a voluntary task that allows simultaneous recording of preference and choice.
Asunto(s)
Conducta de Elección/fisiología , Lóbulo Frontal/fisiología , Neuronas/fisiología , Desempeño Psicomotor/fisiología , Tacto/fisiología , Animales , Femenino , Lóbulo Frontal/química , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , Neuronas/química , Técnicas EstereotáxicasRESUMEN
One hallmark feature of Parkinson's disease (PD) is Lewy body pathology associated with misfolded alpha-synuclein. Previous studies have shown that striatal injection of alpha-synuclein preformed fibrils (PFF) can induce misfolding and aggregation of native alpha-synuclein in a prion-like manner, leading to cell death and motor dysfunction in mouse models. Here, we tested whether alpha-synuclein PFFs injected into the medial prefrontal cortex results in deficits in interval timing, a cognitive task which is disrupted in human PD patients and in rodent models of PD. We injected PFF or monomers of human alpha-synuclein into the medial prefrontal cortex of mice pre-injected with adeno-associated virus (AAV) coding for overexpression of human alpha-synuclein or control protein. Despite notable medial prefrontal cortical synucleinopathy, we did not observe consistent deficits in fixed-interval timing. These results suggest that cortical alpha-synuclein does not reliably disrupt fixed-interval timing.
Asunto(s)
Corteza Cerebral/patología , Cognición/fisiología , Sinucleinopatías/patología , alfa-Sinucleína/toxicidad , Animales , Femenino , Humanos , Ratones , Ratones Endogámicos C57BLRESUMEN
Previous studies have identified dementia as a risk factor for death from coronavirus disease 2019 (COVID-19). However, it is unclear whether Alzheimer's disease (AD) is an independent risk factor for COVID-19 case fatality rate. In a retrospective cohort study, we identified 387,841 COVID-19 patients through TriNetX. After adjusting for demographics and comorbidities, we found that AD patients had higher odds of dying from COVID-19 compared to patients without AD (Odds Ratio: 1.20, 95%confidence interval: 1.09-1.32, pâ<â0.001). Interestingly, we did not observe increased mortality from COVID-19 among patients with vascular dementia. These data are relevant to the evolving COVID-19 pandemic.
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Enfermedad de Alzheimer , COVID-19 , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/mortalidad , COVID-19/complicaciones , COVID-19/mortalidad , Demencia Vascular/complicaciones , Humanos , Estudios Retrospectivos , Factores de RiesgoRESUMEN
Cognitive dysfunction is common in Parkinson's disease (PD) and predicts poor clinical outcomes. It is associated primarily with pathologic involvement of basal forebrain cholinergic and prefrontal dopaminergic systems. Impairments in executive functions, attention, and visuospatial abilities are its hallmark features with eventual involvement of memory and other domains. Subtle symptoms in the premotor and early phases of PD progress to mild cognitive impairment (MCI) which may be present at the time of diagnosis. Eventually, a large majority of PD patients develop dementia with advancing age and longer disease duration, which is usually accompanied by immobility, hallucinations/psychosis, and dysautonomia. Dopaminergic medications and deep brain stimulation help motor dysfunction, but may have potential cognitive side effects. Central acetylcholinesterase inhibitors, and possibly memantine, provide modest and temporary symptomatic relief for dementia, although there is no evidence-based treatment for MCI. There is no proven disease-modifying treatment for cognitive impairment in PD. The symptomatic and disease-modifying role of physical exercise, cognitive training, and neuromodulation on cognitive impairment in PD is under investigation. Multidisciplinary approaches to cognitive impairment with effective treatment of comorbidities, proper rehabilitation, and maintenance of good support systems in addition to pharmaceutical treatment may improve the quality of life of the patients and caregivers.
Asunto(s)
Inhibidores de la Colinesterasa/administración & dosificación , Disfunción Cognitiva/psicología , Disfunción Cognitiva/terapia , Enfermedad de Parkinson/psicología , Enfermedad de Parkinson/terapia , Calidad de Vida/psicología , Nivel de Alerta/efectos de los fármacos , Nivel de Alerta/fisiología , Disfunción Cognitiva/etiología , Donepezilo/administración & dosificación , Función Ejecutiva/efectos de los fármacos , Función Ejecutiva/fisiología , Humanos , Memoria Episódica , Enfermedad de Parkinson/complicaciones , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Rivastigmina/administración & dosificación , Estimulación Eléctrica Transcutánea del Nervio/métodosRESUMEN
Lewy body dementias are characterized by deposition of alpha-synuclein (α-syn) protein aggregates known as Lewy bodies and Lewy neurites in cortical regions, in addition to brainstem. These aggregates are thought to cause the death of dopaminergic neurons in the substantia nigra and other vulnerable cell types in patients, leading to parkinsonism. There is evidence from mice that localized overexpression of wild-type α-syn leads to dopaminergic cell death in the substantia nigra. However, it is not known how cortical neurons are affected by α-syn. In this study, we used viral overexpression of α-syn to investigate whether localized overexpression within the cortex affects the density, length, and morphology of dendritic spines, which serve as a measure of synaptic connectivity. An AAV2/6 viral vector coding for wild-type human α-syn was used to target overexpression bilaterally to the medial prefrontal cortex within adult mice. After ten weeks the brain was stained using the Golgi-Cox method. Density of dendritic spines in the injected region was increased in layer V pyramidal neurons compared with animals injected with control virus. Immunohistochemistry in separate animals showed human α-syn expression throughout the region of interest, especially in presynaptic terminals. However, phosphorylated α-syn was seen in a discrete number of cells at the region of highest overexpression, localized mainly to the soma and nucleus. These findings demonstrate that at early timepoints, α-syn overexpression may alter connectivity in the cortex, which may be relevant to early stages of the disease. In addition, these findings contribute to the understanding of α-syn, which when overexpressed in the wildtype, non-aggregated state may promote spine formation. Loss of spines secondary to α-syn in cortex may require higher expression, longer incubation, cellular damage, concomitant dopaminergic dysfunction or other two-hit factors to lead to synaptic degeneration.
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Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Espinas Dendríticas/metabolismo , Espinas Dendríticas/patología , alfa-Sinucleína/metabolismo , Animales , Humanos , Masculino , RatonesRESUMEN
Western blots are used to estimate the relative concentrations of proteins of interest based on staining by specific antibodies. Quantitative measurements are often subject to error due to overloading of the loading control and over-reliance on normalization. We have found that at the protein concentrations normally used to quantify most low-abundance proteins of interest, frequently used single-protein loading controls, such as glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and beta-actin, do not accurately reflect differences in protein concentration. Two total protein stains, SYPRO Ruby and Amido Black, were compared and found to be acceptable alternatives to single-protein controls. Although we cannot prove that high-abundance loading controls are inaccurate under all possible conditions, we conclude that the burden of proof should lie with the researcher to demonstrate that their loading control is reflective of quantitative differences in protein concentration.
Asunto(s)
Western Blotting/métodos , Proteínas del Tejido Nervioso/análisis , Proteínas del Tejido Nervioso/química , Neuroquímica/métodos , Coloración y Etiquetado/métodos , Negro de Almidón/química , Secuencia de Aminoácidos , Animales , Química Encefálica/fisiología , Colorantes/química , Homólogo 4 de la Proteína Discs Large , Guanilato-Quinasas , Péptidos y Proteínas de Señalización Intracelular/análisis , Péptidos y Proteínas de Señalización Intracelular/química , Proteínas de la Membrana/análisis , Proteínas de la Membrana/química , Ratones , Proteína Quinasa 3 Activada por Mitógenos/análisis , Proteína Quinasa 3 Activada por Mitógenos/química , Compuestos Organometálicos/química , Proteómica , Fracciones SubcelularesRESUMEN
Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are common causes of dementia worldwide. Although considered separate entities based on the relative temporal onset of motor symptoms vs. diagnosis of dementia, it is unknown if these diseases truly have distinct cognitive profiles. We hypothesized that patients divided into PDD and DLB categories strictly by temporal criteria would have different neuropsychological profiles. We investigated this question via neuropsychological testing of PDD and DLB patients at the University of Iowa. We performed retrospective chart analysis and review of neuropsychological testing of clinically diagnosed patients with PDD or DLB, who had presented to University of Iowa's dementia and movement disorder clinics. Forty-seven patients diagnosed by the treating neurologist as PDD or DLB were included. Neuropsychological performance was compared between groups, and as a function of the relative timing of the motor diagnosis vs. diagnosis of dementia. We found that both PDD and DLB patients showed severe deficits in executive function, visual-spatial processing, and verbal learning. However, we found no significant differences in neuropsychological performance between groups, and neuropsychological performance could not reliably account for the relative timing of motor diagnosis vs. diagnosis of dementia. Our data support the idea that DLB and PDD are on a neuropsychological spectrum.
RESUMEN
Behavioral experiences can modulate neural networks through changes in synaptic morphology and number. In contrast, abnormal morphogenesis of dendritic spines is associated with cognitive impairment, as in Fragile X syndrome. Dendritic or synaptic protein synthesis could provide the specificity and speed necessary for spine morphogenesis. Here, we highlight locally translated proteins shown to affect synaptic morphology (e.g., Fragile X mental retardation protein).