RESUMO
BACKGROUND: Although elevated serum levels of visinin-like protein 1 (VILIP-1), a neuron-specific calcium sensor protein, are associated with ischaemic stroke, only a single study has evaluated VILIP-1 as a biomarker of traumatic brain injury (TBI). The current proof-of-concept study was designed to determine whether serum VILIP-1 levels increase post-injury in a well-characterized rat unilateral cortical contusion model. METHODS: Lateral flow devices (LFDs) rapidly (< 20 min) detected trace serum levels (pg/mL) of VILIP-1 in a small input sample volume (10 µL). Temporal profiles of serum levels at baseline and post-injury were measured in male Sprague Dawley rats subjected to very mild-, mild unilateral-cortical contusion, or naïve surgery and in male Sprague Dawley rats following a diffuse TBI or sham surgery. RESULTS: Mean serum levels were significantly elevated by 0.5 h post-injury and remained so throughout the temporal profile compared with baseline in very mild and mild unilateral contusions but not in naïve surgeries. Serum levels were also elevated in a small cohort of animals subjected to a diffuse TBI injury. CONCLUSIONS: Overall, the current study demonstrates that the novel LFD is a reliable and rapid point-of-care diagnostic for the detection and quantification of serum levels of UB-VILIP-1 in a clinically relevant time frame.
Assuntos
Lesões Encefálicas/sangue , Lesões Encefálicas/diagnóstico , Neurocalcina/sangue , Animais , Córtex Cerebral/lesões , Estudos de Coortes , Modelos Animais de Doenças , Células HEK293 , Humanos , Imunoprecipitação , Modelos Lineares , Masculino , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Ubiquitina/metabolismoRESUMO
Increasing evidence suggests that the calcineurin (CN)-dependent transcription factor NFAT (Nuclear Factor of Activated T cells) mediates deleterious effects of astrocytes in progressive neurodegenerative conditions. However, the impact of astrocytic CN/NFAT signaling on neural function/recovery after acute injury has not been investigated extensively. Using a controlled cortical impact (CCI) procedure in rats, we show that traumatic brain injury is associated with an increase in the activities of NFATs 1 and 4 in the hippocampus at 7 d after injury. NFAT4, but not NFAT1, exhibited extensive labeling in astrocytes and was found throughout the axon/dendrite layers of CA1 and the dentate gyrus. Blockade of the astrocytic CN/NFAT pathway in rats using adeno-associated virus (AAV) vectors expressing the astrocyte-specific promoter Gfa2 and the NFAT-inhibitory peptide VIVIT prevented the injury-related loss of basal CA1 synaptic strength and key synaptic proteins and reduced the susceptibility to induction of long-term depression. In conjunction with these seemingly beneficial effects, VIVIT treatment elicited a marked increase in the expression of the prosynaptogenic factor SPARCL1 (hevin), especially in hippocampal tissue ipsilateral to the CCI injury. However, in contrast to previous work on Alzheimer's mouse models, AAV-Gfa2-VIVIT had no effects on the levels of GFAP and Iba1, suggesting that synaptic benefits of VIVIT were not attributable to a reduction in glial activation per se. Together, the results implicate the astrocytic CN/NFAT4 pathway as a key mechanism for disrupting synaptic remodeling and homeostasis in the hippocampus after acute injury. SIGNIFICANCE STATEMENT: Similar to microglia, astrocytes become strongly "activated" with neural damage and exhibit numerous morphologic/biochemical changes, including an increase in the expression/activity of the protein phosphatase calcineurin. Using adeno-associated virus (AAV) to inhibit the calcineurin-dependent activation of the transcription factor NFAT (Nuclear Factor of Activated T cells) selectively, we have shown that activated astrocytes contribute to neural dysfunction in animal models characterized by progressive/chronic neuropathology. Here, we show that the suppression of astrocytic calcineurin/NFATs helps to protect synaptic function and plasticity in an animal model in which pathology arises from a single traumatic brain injury. The findings suggest that at least some astrocyte functions impair recovery after trauma and may provide druggable targets for treating victims of acute nervous system injury.
Assuntos
Astrócitos/fisiologia , Lesões Encefálicas/terapia , Calcineurina/metabolismo , Hipocampo/fisiologia , Fatores de Transcrição NFATC/metabolismo , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Animais , Lesões Encefálicas/genética , Lesões Encefálicas/patologia , Calcineurina/genética , Modelos Animais de Doenças , Técnicas de Transferência de Genes , Vetores Genéticos/administração & dosagem , Masculino , Fatores de Transcrição NFATC/antagonistas & inibidores , Fatores de Transcrição NFATC/genética , Técnicas de Cultura de Órgãos , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/fisiologiaRESUMO
The positron emission tomography (PET) ligand (11) C-labeled Pittsburgh compound B (PIB) is used to image ß-amyloid (Aß) deposits in the brains of living subjects with the intent of detecting early stages of Alzheimer's disease (AD). However, deposits of human-sequence Aß in amyloid precursor protein transgenic mice and non-human primates bind very little PIB. The high stoichiometry of PIB:Aß binding in human AD suggests that the PIB-binding site may represent a particularly pathogenic entity and/or report local pathologic conditions. In this study, (3) H-PIB was employed to track purification of the PIB-binding site in > 90% yield from frontal cortical tissue of autopsy-diagnosed AD subjects. The purified PIB-binding site comprises a distinct, highly insoluble subfraction of the Aß in AD brain with low buoyant density because of the sodium dodecyl sulfate-resistant association with a limited subset of brain proteins and lipids with physical properties similar to lipid rafts and to a ganglioside:Aß complex in AD and Down syndrome brain. Both the protein and lipid components are required for PIB binding. Elucidation of human-specific biological components and pathways will be important in guiding improvement of the animal models for AD and in identifying new potential therapeutic avenues. A lipid-associated subpopulation of Aß accounts for the high-affinity binding of Pittsburgh compound B (PIB) in Alzheimer's disease brain. Mass spectrometry of the isolated PIB-binding site from frontal cortex identified Aß peptides and a set of plaque-associated proteins in AD but not age-matched normal brain. The PIB-binding site may represent a particularly pathogenic entity and/or report local pathologic conditions.
Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/farmacologia , Compostos de Anilina/metabolismo , Química Encefálica/efeitos dos fármacos , Tiazóis/metabolismo , Idoso , Idoso de 80 Anos ou mais , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/genética , Química Encefálica/genética , Síndrome de Down/metabolismo , Feminino , Lobo Frontal/metabolismo , Humanos , Técnicas In Vitro , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , ProteômicaRESUMO
Hippocampal sclerosis of aging (HS-Aging) is a high-morbidity brain disease in the elderly but risk factors are largely unknown. We report the first genome-wide association study (GWAS) with HS-Aging pathology as an endophenotype. In collaboration with the Alzheimer's Disease Genetics Consortium, data were analyzed from large autopsy cohorts: (#1) National Alzheimer's Coordinating Center (NACC); (#2) Rush University Religious Orders Study and Memory and Aging Project; (#3) Group Health Research Institute Adult Changes in Thought study; (#4) University of California at Irvine 90+ Study; and (#5) University of Kentucky Alzheimer's Disease Center. Altogether, 363 HS-Aging cases and 2,303 controls, all pathologically confirmed, provided statistical power to test for risk alleles with large effect size. A two-tier study design included GWAS from cohorts #1-3 (Stage I) to identify promising SNP candidates, followed by focused evaluation of particular SNPs in cohorts #4-5 (Stage II). Polymorphism in the ATP-binding cassette, sub-family C member 9 (ABCC9) gene, also known as sulfonylurea receptor 2, was associated with HS-Aging pathology. In the meta-analyzed Stage I GWAS, ABCC9 polymorphisms yielded the lowest p values, and factoring in the Stage II results, the meta-analyzed risk SNP (rs704178:G) attained genome-wide statistical significance (p = 1.4 × 10(-9)), with odds ratio (OR) of 2.13 (recessive mode of inheritance). For SNPs previously linked to hippocampal sclerosis, meta-analyses of Stage I results show OR = 1.16 for rs5848 (GRN) and OR = 1.22 rs1990622 (TMEM106B), with the risk alleles as previously described. Sulfonylureas, a widely prescribed drug class used to treat diabetes, also modify human ABCC9 protein function. A subsample of patients from the NACC database (n = 624) were identified who were older than age 85 at death with known drug history. Controlling for important confounders such as diabetes itself, exposure to a sulfonylurea drug was associated with risk for HS-Aging pathology (p = 0.03). Thus, we describe a novel and targetable dementia risk factor.
Assuntos
Envelhecimento/genética , Envelhecimento/patologia , Hipocampo/patologia , Polimorfismo de Nucleotídeo Único , Receptores de Sulfonilureias/genética , Idoso de 80 Anos ou mais , Envelhecimento/efeitos dos fármacos , Estudos de Coortes , Bases de Dados como Assunto , Endofenótipos , Estudo de Associação Genômica Ampla , Hipocampo/efeitos dos fármacos , Humanos , Esclerose/genética , Esclerose/patologia , Compostos de Sulfonilureia/efeitos adversos , Compostos de Sulfonilureia/uso terapêuticoRESUMO
Hippocampal sclerosis of aging (HS-Aging) is a causative factor in a large proportion of elderly dementia cases. The current definition of HS-Aging rests on pathologic criteria: neuronal loss and gliosis in the hippocampal formation that is out of proportion to AD-type pathology. HS-Aging is also strongly associated with TDP-43 pathology. HS-Aging pathology appears to be most prevalent in the oldest-old: autopsy series indicate that 5-30 % of nonagenarians have HS-Aging pathology. Among prior studies, differences in study design have contributed to the study-to-study variability in reported disease prevalence. The presence of HS-Aging pathology correlates with significant cognitive impairment which is often misdiagnosed as AD clinically. The antemortem diagnosis is further confounded by other diseases linked to hippocampal atrophy including frontotemporal lobar degeneration and cerebrovascular pathologies. Recent advances characterizing the neurocognitive profile of HS-Aging patients have begun to provide clues that may help identify living individuals with HS-Aging pathology. Structural brain imaging studies of research subjects followed to autopsy reveal hippocampal atrophy that is substantially greater in people with eventual HS-Aging pathology, compared to those with AD pathology alone. Data are presented from individuals who were followed with neurocognitive and neuroradiologic measurements, followed by neuropathologic evaluation at the University of Kentucky. Finally, we discuss factors that are hypothesized to cause or modify the disease. We conclude that the published literature on HS-Aging provides strong evidence of an important and under-appreciated brain disease of aging. Unfortunately, there is no therapy or preventive strategy currently available.
Assuntos
Envelhecimento/patologia , Encefalopatias/epidemiologia , Encefalopatias/patologia , Hipocampo/patologia , Idoso , Humanos , Morbidade , Prevalência , EscleroseRESUMO
Functional plasticity of synaptic networks in the dentate gyrus has been implicated in the development of posttraumatic epilepsy and in cognitive dysfunction after traumatic brain injury, but little is known about potentially pathogenic changes in inhibitory circuits. We examined synaptic inhibition of dentate granule cells and excitability of surviving GABAergic hilar interneurons 8-13 weeks after cortical contusion brain injury in transgenic mice that express enhanced green fluorescent protein in a subpopulation of inhibitory neurons. Whole-cell voltage-clamp recordings in granule cells revealed a reduction in spontaneous and miniature IPSC frequency after head injury; no concurrent change in paired-pulse ratio was found in granule cells after paired electrical stimulation of the hilus. Despite reduced inhibitory input to granule cells, action potential and EPSC frequencies were increased in hilar GABA neurons from slices ipsilateral to the injury versus those from control or contralateral slices. Furthermore, increased excitatory synaptic activity was detected in hilar GABA neurons ipsilateral to the injury after glutamate photostimulation of either the granule cell or CA3 pyramidal cell layers. Together, these findings suggest that excitatory drive to surviving hilar GABA neurons is enhanced by convergent input from both pyramidal and granule cells, but synaptic inhibition of granule cells is not fully restored after injury. This rewiring of circuitry regulating hilar inhibitory neurons may reflect an important compensatory mechanism, but it may also contribute to network destabilization by increasing the relative impact of surviving individual interneurons in controlling granule cell excitability in the posttraumatic dentate gyrus.
Assuntos
Lesões Encefálicas/fisiopatologia , Giro Denteado/fisiopatologia , Interneurônios/fisiologia , Rede Nervosa/fisiopatologia , Sinapses/fisiologia , Animais , Eletrofisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Potenciais Pós-Sinápticos Inibidores/fisiologia , Masculino , Camundongos , Potenciais Pós-Sinápticos em Miniatura/fisiologia , Estatísticas não Paramétricas , Ácido gama-Aminobutírico/metabolismoRESUMO
Mild cognitive impairment (MCI) is rapidly becoming one of the most common clinical manifestations affecting the elderly. The pathologic and molecular substrate of people diagnosed with MCI is not well established. Since MCI is a human specific disorder and neither the clinical nor the neuropathological course appears to follow a direct linear path, it is imperative to characterize neuropathology changes in the brains of people who came to autopsy with a well-characterized clinical diagnosis of MCI. Herein, we discuss findings derived from clinical pathologic studies of autopsy cases who died with a clinical diagnosis of MCI. The heterogeneity of clinical MCI imparts significant challenges to any review of this subject. The pathologic substrate of MCI is equally complex and must take into account not only conventional plaque and tangle pathology but also a wide range of cellular, biochemical and molecular deficits, many of which relate to cognitive decline as well as compensatory responses to the progressive disease process. The multifaceted nature of the neuronal disconnection syndrome associated with MCI suggests that there is no single event which precipitates this prodromal stage of AD. In fact, it can be argued that neuronal degeneration initiated at different levels of the central nervous system drives cognitive decline as a final common pathway at this stage of the dementing disease process.
Assuntos
Encéfalo/patologia , Disfunção Cognitiva/patologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Encéfalo/metabolismo , Disfunção Cognitiva/etiologia , Progressão da Doença , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Fatores de Crescimento Neural/metabolismo , Emaranhados Neurofibrilares/patologia , Neurônios/metabolismo , Doença de Parkinson/patologia , Placa Amiloide/patologia , Receptores Colinérgicos/metabolismo , Sinapses/ultraestruturaRESUMO
Alterations in the relative abundance of synaptic proteins may contribute to hippocampal synaptic dysfunction in Alzheimer's disease (AD). The extent to which perturbations in synaptic protein expression occur during the earliest stages of cognitive decline remains unclear. We examined protein levels of presynaptic synaptophysin (SYP) and synaptotagmin (SYT), and postsynaptic drebrin (DRB), a marker for dendritic spine plasticity, in the hippocampus of people with an antemortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI) or mild/moderate AD. Although normalized SYP and SYT levels were preserved, DRB was reduced by approximately 40% in the hippocampus of MCI and AD compared to NCI subjects. This differential alteration of synaptic markers in MCI suggests a selective impairment in hippocampal postsynaptic dendritic plasticity in prodromal AD that likely heralds the onset of memory impairment in symptomatic disease.
Assuntos
Disfunção Cognitiva/patologia , Hipocampo/metabolismo , Neuropeptídeos/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/patologia , Feminino , Regulação da Expressão Gênica , Humanos , Masculino , Escalas de Graduação Psiquiátrica , Estatísticas não Paramétricas , Sinaptofisina/metabolismo , Sinaptotagminas/metabolismoRESUMO
Human studies are reviewed concerning whether "aging"-related mechanisms contribute to Alzheimer's disease (AD) pathogenesis. AD is defined by specific neuropathology: neuritic amyloid plaques and neocortical neurofibrillary tangles. AD pathology is driven by genetic factors related not to aging per se, but instead to the amyloid precursor protein (APP). In contrast to genes involved in APP-related mechanisms, there is no firm connection between genes implicated in human "accelerated aging" diseases (progerias) and AD. The epidemiology of AD in advanced age is highly relevant but deceptively challenging to address given the low autopsy rates in most countries. In extreme old age, brain diseases other than AD approximate AD prevalence while the impact of AD pathology appears to peak by age 95 and decline thereafter. Many distinct brain diseases other than AD afflict older human brains and contribute to cognitive impairment. Additional prevalent pathologies include cerebrovascular disease and hippocampal sclerosis, both high-morbidity brain diseases that appear to peak in incidence later than AD chronologically. Because of these common brain diseases of extreme old age, the epidemiology differs between clinical "dementia" and the subset of dementia cases with AD pathology. Additional aging-associated mechanisms for cognitive decline such as diabetes and synapse loss have been linked to AD and these hypotheses are discussed. Criteria are proposed to define an "aging-linked" disease, and AD fails all of these criteria. In conclusion, it may be most fruitful to focus attention on specific pathways involved in AD rather than attributing it to an inevitable consequence of aging.
Assuntos
Envelhecimento/genética , Envelhecimento/patologia , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Encéfalo/patologia , Neurônios/patologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/epidemiologia , Predisposição Genética para Doença/epidemiologia , Predisposição Genética para Doença/genética , Humanos , Fatores de RiscoRESUMO
The cerebral neuropathology of Type 2 diabetes (CNDM2) has not been positively defined. This review includes a description of CNDM2 research from before the 'Pubmed Era'. Recent neuroimaging studies have focused on cerebrovascular and white matter pathology. These and prior studies about cerebrovascular histopathology in diabetes are reviewed. Evidence is also described for and against the link between CNDM2 and Alzheimer's disease pathogenesis. To study this matter directly, we evaluated data from University of Kentucky Alzheimer's Disease Center (UK ADC) patients recruited while non-demented and followed longitudinally. Of patients who had come to autopsy (N = 234), 139 met inclusion criteria. These patients provided the basis for comparing the prevalence of pathological and clinical indices between well-characterized cases with (N = 50) or without (N = 89) the premortem diagnosis of diabetes. In diabetics, cerebrovascular pathology was more frequent and Alzheimer-type pathology was less frequent than in non-diabetics. Finally, a series of photomicrographs demonstrates histopathological features (including clinical-radiographical correlation) observed in brains of persons that died after a history of diabetes. These preliminary, correlative, and descriptive studies may help develop new hypotheses about CNDM2. We conclude that more work should be performed on human material in the context of CNDM2.
Assuntos
Encéfalo/patologia , Transtornos Cognitivos/patologia , Demência/patologia , Diabetes Mellitus Tipo 2/patologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/etiologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Encéfalo/irrigação sanguínea , Encéfalo/metabolismo , Estudos de Casos e Controles , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/metabolismo , Demência/etiologia , Demência/metabolismo , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Feminino , Humanos , Hipoglicemia/complicações , Hipoglicemia/metabolismo , Hipoglicemia/patologia , Masculino , Estudos RetrospectivosRESUMO
Posttraumatic epilepsy is a frequent consequence of brain trauma, but relatively little is known about how neuronal circuits are chronically altered after closed head injury. We examined whether local recurrent excitatory synaptic connections form between dentate granule cells in mice 8-12 wk after cortical contusion injury. Mice were monitored for behavioral seizures shortly after brain injury and < or = 10 wk postinjury. Injury-induced seizures were observed in 15% of mice, and spontaneous seizures were observed weeks later in 40% of mice. Timm's staining revealed mossy fiber sprouting into the inner molecular layer of the dorsal dentate gyrus ipsilateral to the injury in 95% of mice but not contralateral to the injury or in uninjured controls. Whole cell patch-clamp recordings were made from granule cells in isolated hippocampal brain slices. Cells in slices with posttraumatic mossy fiber sprouting had an increased excitatory postsynaptic current (EPSC) frequency compared with cells in slices without sprouting from injured and control animals (P < 0.001). When perfused with Mg(2+)-free artificial cerebrospinal fluid containing 100 microM picrotoxin, these cells had spontaneous bursts of EPSCs and action potentials. Focal glutamate photostimulation of the granule cell layer evoked a burst of EPSCs and action potentials indicative of recurrent excitatory connections in granule cells of slices with mossy fiber sprouting. In granule cells of slices without sprouting from injured animals and controls, spontaneous or photostimulation-evoked epileptiform activity was never observed. These results suggest that a new regionally localized excitatory network forms between dentate granule cells near the injury site within weeks after cortical contusion head injury.
Assuntos
Lesões Encefálicas/complicações , Lesões Encefálicas/fisiopatologia , Giro Denteado/fisiopatologia , Epilepsia/etiologia , Epilepsia/fisiopatologia , Animais , Lesões Encefálicas/patologia , Contusões/patologia , Contusões/fisiopatologia , Interpretação Estatística de Dados , Giro Denteado/patologia , Eletrofisiologia , Epilepsia/patologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Ácido Glutâmico/fisiologia , Imuno-Histoquímica , Técnicas In Vitro , Masculino , Potenciais da Membrana/fisiologia , Camundongos , Fibras Musgosas Hipocampais/patologia , Fibras Musgosas Hipocampais/fisiopatologia , Técnicas de Patch-Clamp , Estimulação Luminosa , Sinapses/fisiologiaRESUMO
BACKGROUND: Neuroinflammation contributes to the pathophysiology of acute CNS injury, including traumatic brain injury (TBI). Although prostaglandin lipid mediators of inflammation contribute to a variety of inflammatory responses, their importance in neuroinflammation is not clear. There are conflicting reports as to the efficacy of inhibiting the enzymes required for prostaglandin formation, cyclooxygenase (COX) -1 and COX-2, for improving outcomes following TBI. The purpose of the current study was to determine the role of the COX isoforms in contributing to pathological processes resulting from TBI by utilizing mice deficient in COX-1 or COX-2. RESULTS: Following a mild controlled cortical impact injury, the amount of cortical tissue loss, the level of microglial activation, and the capacity for functional recovery was compared between COX-1-deficient mice or COX-2-deficient mice, and their matching wild-type controls. The deficiency of COX-2 resulted in a minor (6%), although statistically significant, increase in the sparing of cortical tissue following TBI. The deficiency of COX-1 resulted in no detectable effect on cortical tissue loss following TBI. As determined by 3[H]-PK11195 autoradiography, TBI produced a similar increase in microglial activation in multiple brain regions of both COX-1 wild-type and COX-1-deficient mice. In COX-2 wild-type and COX-2-deficient mice, TBI increased 3[H]-PK11195 binding in all brain regions that were analyzed. Following injury, 3[H]-PK11195 binding in the dentate gyrus and CA1 region of the hippocampus was greater in COX-2-deficient mice, as compared to COX-2 wild-type mice. Cognitive assessment was performed in the wild-type, COX-1-deficient and COX-2-deficient mice following 4 days of recovery from TBI. There was no significant cognitive effect that resulted from the deficiency of either COX-1 or COX-2, as determined by acquisition and spatial memory retention testing in a Morris water maze. CONCLUSION: These findings suggest that the deficiency of neither COX-1 nor COX-2 is sufficient to alter cognitive outcomes following TBI in mice.
Assuntos
Lesões Encefálicas/enzimologia , Ciclo-Oxigenase 1/deficiência , Ciclo-Oxigenase 2/deficiência , Análise de Variância , Animais , Autorradiografia , Lesões Encefálicas/patologia , Lesões Encefálicas/fisiopatologia , Córtex Cerebral/enzimologia , Córtex Cerebral/patologia , Córtex Cerebral/fisiopatologia , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 2/genética , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Knockout , Microglia/metabolismo , Microglia/patologia , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/metabolismo , Núcleos Talâmicos/enzimologia , Núcleos Talâmicos/fisiologia , Núcleos Talâmicos/fisiopatologiaRESUMO
We studied Alzheimer's disease (AD) pathology in the precuneus and surrounding brain areas. Anatomically, the precuneus corresponds to the medial portion of human cerebral cortical Brodmann Area 7. This study utilized patients from the University of Kentucky Alzheimer's Disease Center autopsy cohort. Data from 47 brains were used comprising patients of differing antemortem cognitive impairment severities, each with longitudinal clinical data and extensive neuropathological data. We assessed whether the precuneus and surrounding areas are differentially vulnerable to AD-type pathological lesions (diffuse amyloid plaques, neuritic amyloid plaques, and neurofibrillary tangles). Eleven areas of brain were evaluated for each case: amygdala, hippocampal CA1, subiculum, entorhinal cortex, frontal cortex, superior and middle temporal gyri, inferior parietal lobule, occipital cortex, posterior cingulate gyrus, Brodmann Area 31, and the precuneus proper. Like other areas of neocortex, the precuneus demonstrated increased diffuse and neuritic amyloid plaques early in the evolution in AD, and increased neurofibrillary tangles late in AD. Correcting for the antemortem cognitive status of the patients, there was no evidence of an increase in the density of AD-type pathology in the precuneus or neighboring areas relative to other areas of cerebral neocortex. Our results are not consistent with the idea that the precuneus is involved in a special way with plaques or tangles relative to other areas of neocortex.
Assuntos
Doença de Alzheimer/patologia , Transtornos Cognitivos/patologia , Neocórtex/patologia , Degeneração Neural/patologia , Neurônios/patologia , Lobo Parietal/patologia , Idoso de 80 Anos ou mais , Doença de Alzheimer/fisiopatologia , Tonsila do Cerebelo/patologia , Tonsila do Cerebelo/fisiopatologia , Mapeamento Encefálico , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/fisiopatologia , Progressão da Doença , Hipocampo/patologia , Hipocampo/fisiopatologia , Humanos , Neocórtex/fisiopatologia , Degeneração Neural/fisiopatologia , Emaranhados Neurofibrilares/patologia , Lobo Parietal/fisiopatologia , Placa Amiloide/patologiaRESUMO
Oxidative stress, an imbalance between oxidants and antioxidants, contributes to the pathogenesis of traumatic brain injury (TBI). Oxidative neurodegeneration is a key mediator of exacerbated morphological responses and deficits in behavioral recoveries. The present study assessed early hippocampal sequential imbalance to possibly enhance antioxidant therapy. Young adult male Sprague-Dawley rats were subjected to a unilateral moderate cortical contusion. At various times post-TBI, animals were killed and the hippocampus was analyzed for antioxidants (GSH, GSSG, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, glucose-6-phosphate dehydrogenase, superoxide dismutase, and catalase) and oxidants (acrolein, 4-hydroxynonenal, protein carbonyl, and 3-nitrotyrosine). Synaptic markers (synapsin I, postsynaptic density protein 95, synapse-associated protein 97, growth-associated protein 43) were also analyzed. All values were compared with those for sham-operated animals. Significant time-dependent changes in antioxidants were observed as early as 3 h posttrauma and paralleled increases in oxidants (4-hydroxynonenal, acrolein, and protein carbonyl), with peak values obtained at 24-48 h. Time-dependent changes in synaptic proteins (synapsin I, postsynaptic density protein 95, and synapse-associated protein 97) occurred well after levels of oxidants peaked. These results indicate that depletion of antioxidant systems following trauma could adversely affect synaptic function and plasticity. Early onset of oxidative stress suggests that the initial therapeutic window following TBI appears to be relatively short, and it may be necessary to stagger selective types of antioxidant therapy to target specific oxidative components.
Assuntos
Lesões Encefálicas/metabolismo , Hipocampo/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Estresse Oxidativo , Sinapses/metabolismo , Animais , Lesões Encefálicas/patologia , Morte Celular , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Hipocampo/patologia , Peroxidação de Lipídeos , Masculino , Nitratos/metabolismo , Oxirredução , Ratos , Ratos Sprague-DawleyRESUMO
Oxidative stress is one of the hypotheses involved in the etiology of Alzheimer's disease (AD). Considerable attention has been focused on increasing the intracellular glutathione (GSH) levels in many neurodegenerative diseases, including AD. Pycnogenol (PYC) has antioxidant properties and stabilizes intracellular antioxidant defense systems including glutathione levels. The present study investigated the protective effects of PYC on acrolein-induced oxidative cell toxicity in cultured SH-SY5Y neuroblastoma cells. Decreased cell survival in SH-SY5Y cultures treated with acrolein correlated with oxidative stress, increased NADPH oxidase activity, free radical production, protein oxidation/nitration (protein carbonyl, 3-nitrotyrosine), and lipid peroxidation (4-hydroxy-2-nonenal). Pretreatment with PYC significantly attenuated acrolein-induced cytotoxicity, protein damage, lipid peroxidation, and cell death. A dose-response study suggested that PYC showed protective effects against acrolein toxicity by modulating oxidative stress and increasing GSH. These findings provide support that PYC may provide a promising approach for the treatment of oxidative stress-related neurodegenerative diseases such as AD.
Assuntos
Acroleína/farmacologia , Flavonoides/farmacologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fármacos Neuroprotetores/farmacologia , Aldeídos/metabolismo , Análise de Variância , Western Blotting , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Citotoxinas/farmacologia , Radicais Livres/metabolismo , Glutationa/metabolismo , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Luminescência , NADPH Oxidases/efeitos dos fármacos , NADPH Oxidases/metabolismo , Neuroblastoma , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais , Carbonilação Proteica/efeitos dos fármacos , Tirosina/análogos & derivados , Tirosina/efeitos dos fármacos , Tirosina/metabolismoRESUMO
An imbalance between oxidants and antioxidants has been postulated to lead to oxidative damage in traumatic brain injury (TBI). Oxidative neurodegeneration is a key mediator of exacerbated morphological responses and deficits in behavioral recoveries. The present study was designed to delineate the early temporal sequence of this imbalance in order to enhance possible antioxidant therapy. Young adult male Sprague-Dawley rats were subjected to a unilateral moderate cortical contusion. At various times post-trauma (3, 6, 12, 24, 48, 72, and 96 h), animals were killed and the cortex analyzed for enzymatic and non-enzymatic oxidative stress markers. Fresh tissues were prepared for biochemical analysis of several antioxidants (glutathione [GSH], glutathione peroxidase [GPx], glutathione reductase [GR], glutathione-S-transferase [GST], and thiobarbituric acid reactive substances [TBARS]). Synaptic markers Synapsin-I, PSD-95, SAP-97 and GAP-43 were analyzed by Western blot with antibodies directed against them. All activity levels were compared to sham-operated animals. Activity of antioxidant enzymes and GSH clearly demonstrate a significant time-dependent increase in oxidative stress. Changes in pre- and post-synaptic proteins (Synapsin-I and PSD-95) occur early (24 h), whereas SAP-97 levels demonstrate a protracted reduction. These results indicate that depletion of antioxidant systems following trauma could adversely affect synaptic function and plasticity. Because of the observed differences in the time-course of various markers, it may be necessary to stagger selective types of anti-oxidant therapy to target specific oxidative components. The initial therapeutic window following TBI appears relatively short since oxidative damage occurs as early as 3 h.
Assuntos
Lesões Encefálicas/fisiopatologia , Córtex Cerebral/fisiopatologia , Estresse Oxidativo/fisiologia , Sinapses/metabolismo , Animais , Western Blotting , Lesões Encefálicas/metabolismo , Córtex Cerebral/metabolismo , Proteína 4 Homóloga a Disks-Large , Proteína GAP-43/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , Guanilato Quinases , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Proteínas de Membrana/metabolismo , Ratos , Ratos Sprague-Dawley , Sinapses/patologia , Sinapsinas/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , TempoRESUMO
Traumatic brain injury (TBI) results in an accumulation of edema and loss of brain tissue. Progesterone (PROG) has been reported to reduce edema and cortical tissue loss in a bilateral prefrontal cortex injury. This study tests the hypothesis that PROG is neuroprotective following a unilateral parietal cortical contusion injury (CCI). Adult male Sprague-Dawley rats were subjected to a moderate unilateral TBI using the CCI model. Rats were given 8 mg/kg PROG 15 min post-injury with four subsequent injections (6 h, and days 1, 2, and 3). Edema was determined 3 days post-injury, while cortical tissue sparing was also evaluated at 7 days post-injury. Animals were injured and given one of four treatments: (I) vehicle; (II) low dose: 8 mg/kg PROG; (III) high dose: 16 mg/kg PROG; (IV) tapered: 8 mg/kg PROG. Animals were given an initial injection within 15 min, followed by five injections (6 h, and days 1, 2, 3, and 4). Group IV received two additional injections (4 mg/kg on day 5; 2 mg/kg on day 6). PROG failed to alter both cortical edema and tissue sparing at any dose. Failure to modify two major sequelae associated with TBI brings into question the clinical usefulness of PROG as an effective treatment for all types of brain injury.
Assuntos
Edema Encefálico/prevenção & controle , Lesões Encefálicas/tratamento farmacológico , Encéfalo/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Progesterona/farmacologia , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Edema Encefálico/patologia , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Citoproteção/efeitos dos fármacos , Citoproteção/fisiologia , Modelos Animais de Doenças , Progressão da Doença , Relação Dose-Resposta a Droga , Esquema de Medicação , Lateralidade Funcional , Masculino , Fármacos Neuroprotetores/uso terapêutico , Tamanho do Órgão , Progesterona/uso terapêutico , Ratos , Ratos Sprague-Dawley , Falha de Tratamento , Resultado do TratamentoRESUMO
Novel pharmacological approaches that safely and effectively lessen the degree of neurological impairment following traumatic brain injury (TBI) are sorely needed. Non-invasive approaches that could be used over an extended periods of time might be particularly useful. Previous studies from our lab have hypothesized that TBI-induced decreases in hippocampal and cortical alpha7 neuronal nicotinic cholinergic receptor (nAChR) expression might contribute to cognitive impairment that follows brain injury. The purpose of this study was to determine whether the low-potency, but selective alpha7 nAChR agonist choline might be a useful treatment for improvement of neurological outcome in a rat model of TBI. Male Sprague-Dawley rats were exposed to control or choline-supplemented diets for 2 weeks prior to experimental brain injury (1.5-mm cortical contusion injury) and throughout the recovery phase. Dietary choline supplementation resulted in a modest degree of improvement in spatial memory as assessed in the Morris water maze test. In addition, choline treatment resulted in significant cortical tissue sparing, reduced brain inflammation, and normalized some TBI-induced deficits in nAChR expression. The results of this study suggest that alpha7 nAChR agonists may be useful drugs to enhance recovery following brain injury.
Assuntos
Lesões Encefálicas/dietoterapia , Colina/uso terapêutico , Suplementos Nutricionais , Nootrópicos/uso terapêutico , Animais , Lesões Encefálicas/patologia , Lesões Encefálicas/psicologia , Modelos Animais de Doenças , Masculino , Aprendizagem em Labirinto , Memória , Ratos , Ratos Sprague-Dawley , Receptores Nicotínicos/metabolismoRESUMO
The detection of neuron-specific proteins in blood might allow quantification of the degree of neuropathology in experimental and clinical contexts. We have been studying a novel blood biomarker of axonal injury, the heavily phosphorylated axonal form of the high molecular weight neurofilament subunit NF-H (pNF-H). We hypothesized that this protein would be released from damaged and degenerating neurons following experimental traumatic brain injury (TBI) in amounts large enough to allow its detection in blood and that the levels detected would reflect the degree of injury severity. An enzyme-linked immunosorbent assay (ELISA) capture assay capable of detecting nanogram amounts of pNF-H was used to test blood of rats subjected to experimental TBI using a controlled cortical impact (CCI) device. Animals were subjected to a mild (1.0 mm), moderate (1.5 mm), or severe (2.0 mm) cortical contusion, and blood samples were taken at defined times post-injury. The assay detected the presence of pNF-H as early as 6 h post-injury; levels peaked at 24-48 h, and then slowly decreased to baseline over several days post-injury. No signal above baseline was detectable in control animals. Analysis of variance (ANOVA) showed a significant effect of lesion severity, and post hoc analysis revealed that animals given a moderate and severe contusion showed higher levels of blood pNF-H than controls. In addition, the peak levels of pNF-H detected at both 24 and 48 h post-injury correlated with the degree of injury as determined by volumetric analysis of spared cortical tissue. Relative amounts of pNF-H were also determined in different areas of the central nervous system (CNS) and were found to be highest in regions containing large-diameter axons, including spinal cord and brainstem, and lowest in the cerebral cortex and hippocampus. These findings suggest that the measurement of blood levels of pNF-H is a convenient method for assessing neuropathology following TBI.
Assuntos
Lesões Encefálicas/sangue , Lesões Encefálicas/patologia , Proteínas de Neurofilamentos/sangue , Animais , Biomarcadores/sangue , Encéfalo/patologia , Ensaio de Imunoadsorção Enzimática , Masculino , Proteínas de Neurofilamentos/metabolismo , Fosforilação , Ratos , Ratos Sprague-DawleyRESUMO
Recent attention has been given to gender differences in neurotrauma, and the anecdotal suggestion is that females have better outcomes than males, suggesting that circulating levels of estrogen (E(2)) may be neuroprotective. In order to address this issue, both young adult male and ovariectomized female rats were subjected to a T10 spinal cord injury (SCI), and E2 levels were maintained at chronic, constant circulating levels. Animals were clinically evaluated for locomotor changes using the Basso-Beattie-Bresnahan (BBB) scoring system. Morphologic differences were evaluated with unbiased stereology. Data analysis failed to reveal any significant benefit for the E2 therapy in either males or females. We did find a non-estrogen-dependent difference between male and female rats in length of injury, and percent of spared tissue, with female outcomes more favorable. These results suggest that E(2) does not provide a viable therapy following SCI.