RESUMO
Ureases are microbial virulence factors either because of the enzymatic release of ammonia or due to many other non-enzymatic effects. Here we studied two neurotoxic urease isoforms, Canatoxin (CNTX) and Jack Bean Urease (JBU), produced by the plant Canavalia ensiformis, whose mechanisms of action remain elusive. The neurotoxins provoke convulsions in rodents (LD50 â¼2 mg/kg) and stimulate exocytosis in cell models, affecting intracellular calcium levels. Here, electrophysiological and brain imaging techniques were applied to elucidate their mode of action. While systemic administration of the toxins causes tonic-clonic seizures in rodents, JBU injected into rat hippocampus induced spike-wave discharges similar to absence-like seizures. JBU reduced the amplitude of compound action potential from mouse sciatic nerve in a tetrodotoxin-insensitive manner. Hippocampal slices from CNTX-injected animals or slices treated in vitro with JBU failed to induce long term potentiation upon tetanic stimulation. Rat cortical synaptosomes treated with JBU released L-glutamate. JBU increased the intracellular calcium levels and spontaneous firing rate in rat hippocampus neurons. MicroPET scans of CNTX-injected rats revealed increased [18]Fluoro-deoxyglucose uptake in epileptogenesis-related areas like hippocampus and thalamus. Curiously, CNTX did not affect voltage-gated sodium, calcium or potassium channels currents, neither did it interfere on cholinergic receptors, suggesting an indirect mode of action that could be related to the ureases' membrane-disturbing properties. Understanding the neurotoxic mode of action of C. ensiformis ureases could help to unveil the so far underappreciated relevance of these toxins in diseases caused by urease-producing microorganisms, in which the human central nervous system is affected.
Assuntos
Canavalia/química , Síndromes Neurotóxicas/etiologia , Proteínas de Plantas/toxicidade , Toxinas Biológicas/toxicidade , Urease/toxicidade , Animais , Convulsivantes/isolamento & purificação , Convulsivantes/toxicidade , Feminino , Masculino , Camundongos , Sistema Nervoso/efeitos dos fármacos , Sistema Nervoso/patologia , Síndromes Neurotóxicas/fisiopatologia , Proteínas de Plantas/isolamento & purificação , Ratos , Ratos Wistar , Toxinas Biológicas/isolamento & purificação , Urease/isolamento & purificação , Xenopus laevisRESUMO
BACKGROUND: Inflammation could be a risk factor for the development of depression and change the outcome of this common chronic-recurrent mental disorder. AIMS: This study aimed to investigate if bone marrow mononuclear cell (BMMC) transplantation is effective in restoring sucrose preference in rats subjected to chronic stress (CS), if it has an anti-inflammatory effect and is able to restore damaged DNA. METHODS: The effect of BMMC transplantation was studied in a controlled protocol (compared with a control group and a selective serotonin reuptake inhibitor escitalopram group) involving sucrose preference in CS in rats. Measurements were taken of the amygdala, hippocampus, frontal cortex, and other brain areas, the spleen and blood pro-inflammatory cytokines, namely interleukin-1ß, interleukin-6, tumor necrosis factor-alpha, and interferon-gamma, as well as anti-inflammatory cytokine interleukin-10. Finally, 8-hydroxy-2'-deoxyguanosine (a DNA damage marker) was determined. RESULTS: BMMC transplantation was as effective as escitalopram in restoring sucrose preference. It also had an anti-inflammatory effect and slightly improved damaged DNA after one week. CONCLUSIONS: These findings suggest administration of BMMC in rats subjected to CS restores sucrose preference, resolves inflammation in both the peripheral and central nervous system, as well as diminishes DNA damage. This effect was similar to that of escitalopram, which is effective in the treatment of depressive patients.
Assuntos
Antidepressivos/farmacologia , Comportamento Animal , Transplante de Medula Óssea , Dano ao DNA/efeitos dos fármacos , Inflamação/cirurgia , Sistema Nervoso , Transplante de Células-Tronco , Estresse Psicológico/cirurgia , Animais , Comportamento Animal/efeitos dos fármacos , Doença Crônica , Citalopram/farmacologia , Inflamação/tratamento farmacológico , Masculino , Sistema Nervoso/efeitos dos fármacos , Ratos , Ratos Wistar , Estresse Psicológico/tratamento farmacológicoRESUMO
OBJECTIVE: Temporal lobe epilepsy (TLE) is one of the most common types of epilepsy syndromes in the world. Depression is an important comorbidity of epilepsy, which has been reported in patients with TLE and in different experimental models of epilepsy. However, there is no established consensus on which brain regions are associated with the manifestation of depression in epilepsy. Here, we investigated the alterations in cerebral glucose metabolism and the metabolic network in the pilocarpine-induced rat model of epilepsy and correlated it with depressive behavior during the chronic phase of epilepsy. METHODS: Fluorodeoxyglucose (18 F-FDG) was used to investigate the cerebral metabolism, and a cross-correlation matrix was used to examine the metabolic network in chronically epileptic rats using micro-positron emission tomography (microPET) imaging. An experimental model of epilepsy was induced by pilocarpine injection (320 mg/kg, ip). Forced swim test (FST), sucrose preference test (SPT), and eating-related depression test (ERDT) were used to evaluate depression-like behavior. RESULTS: Our results show an association between epilepsy and depression comorbidity based on changes in both cerebral glucose metabolism and the functional metabolic network. In addition, we have identified a significant correlation between brain glucose hypometabolism and depressive-like behavior in chronically epileptic rats. Furthermore, we found that the epileptic depressed group presents a hypersynchronous brain metabolic network in relation to the epileptic nondepressed group. SIGNIFICANCE: This study revealed relevant alterations in glucose metabolism and the metabolic network among the brain regions of interest for both epilepsy and depression pathologies. Thus it seems that depression in epileptic animals is associated with a more diffuse hypometabolism and altered metabolic network architecture and plays an important role in chronic epilepsy.
Assuntos
Encéfalo/metabolismo , Depressão/etiologia , Epilepsia/metabolismo , Epilepsia/psicologia , Glucose/metabolismo , Animais , Encéfalo/fisiopatologia , Comorbidade , Depressão/metabolismo , Epilepsia/fisiopatologia , Interpretação de Imagem Assistida por Computador , Masculino , Tomografia por Emissão de Pósitrons , Ratos , Ratos WistarRESUMO
AIMS: In previous studies, transplantation of bone marrow mononuclear cells (BMMCs) in epileptic animals has been found to be neuroprotective. However, the mechanism by which the BMMCs act remains unclear. We hypothesize that BMMCs may provide neuroprotection to the epileptic brain through trophic support. To test our hypothesis, we studied the temporal expression of neurotrophins after BMMC transplantation in the epileptic rat hippocampus. METHODS: Chronically epileptic rats were intravenously transplanted with 1 × 10(7) BMMCs isolated from GFP transgenic mice. Expression levels of BDNF, GDNF, NGF, VEGF, and TGF-ß1, and their receptors, were evaluated by ELISA and/or qRT-PCR analysis. RESULTS: Our data revealed increased protein expression of BDNF, GDNF, NGF, and VEGF and reduced levels of TGF-ß1 in the hippocampus of transplanted epileptic animals. Additionally, an increase in the mRNA expression of BDNF, GDNF, and VEGF, a reduction in TGF-ß1, and a decrease in mRNA levels of the TrkA and TGFR-ß1 receptors were also observed. CONCLUSION: The gain provided by transplanted BMMCs in the epileptic brain may be related to the ability of these cells in modulating the network of neurotrophins and angiogenic signals.
Assuntos
Transplante de Medula Óssea , Epilepsia/metabolismo , Epilepsia/terapia , Hipocampo/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Animais , Células da Medula Óssea/metabolismo , Doença Crônica , Modelos Animais de Doenças , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pilocarpina , Ratos WistarRESUMO
Functional magnetic resonance imaging (fMRI) is a non-invasive brain imaging technique widely used in the evaluation of the brain function that provides images with high temporal and spatial resolution. Investigation of the supplementary motor area (SMA) function is critical in the pre-surgical evaluation of neurological patients, since marked individual differences and complex overlapping with adjacent cortical areas exist, and it is important to spare the SMA from lesions when adjacent cortical tissue is surgically removed. We used fMRI to assess the activity of SMA in six right-handed and six left-handed healthy volunteers when a task requiring silent repetition of a series of words was given. Brain activation areas in each of the subjects were localized according to the standard Talairach coordinate space, and the individual voxels for each map were compared after 3D sagittal images were created and SMA was delimited. Quantitative analysis of hemispheric and bilateral SMA activation was described as mean ± standard deviation of hot points/total points. The results show that the language task induced bilateral SMA activation. Left SMA activation was significantly higher than right SMA activation in both right-handed and left-handed subjects.
Assuntos
Lobo Frontal/fisiologia , Lateralidade Funcional/fisiologia , Idioma , Córtex Motor/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Mapeamento Encefálico , Neuroimagem Funcional , Humanos , Imageamento por Ressonância MagnéticaRESUMO
Patulin, a known mycotoxin, is considered a significant contaminant in apples, apple-derived products and feeds. This study investigated the genotoxic effects of patulin in multiple organs (brain, kidney, liver and urinary bladder) of mice using an in vivo comet assay. We assessed the mechanism underlying this genotoxicity by measuring the GSH content and the thiobarbituric acid-reactive species (TBARS) level. Male CF-1 mice were given 1.0-3.75 mg/kg patulin intraperitoneally. The effect of patulin was dose-dependent and the highest patulin dose induced DNA strand breaks in the brain (damage index, DI, in hippocampus increased from 36.2 in control animals to 127.5), liver (44.3-138.4) and kidneys (31.5-99); decreased levels of GSH (hippocampus--from 46.9 to 18.4 nmol/mg protein); and an increase in lipid peroxidation (hippocampus--from 5.8 to 20.3 MDA equivalents/mg protein). This finding establishes an interrelationship between the pro-oxidant and genotoxic effects of patulin. Pre-treatment administration of N-acetyl-cysteine reduced patulin-induced DNA damage (hippocampus--DI from 127.5 to 39.8) and lipid peroxidation (hippocampus--20.3 to 12.8 MDA equivalents/mg protein) by restoring cellular GSH levels, reinforcing the positive relationship between patulin-induced GSH depletion and DNA damage caused by systemic administration of this mycotoxin.
Assuntos
Dano ao DNA/efeitos dos fármacos , Patulina/toxicidade , Acetilcisteína/farmacologia , Animais , Ensaio Cometa , Relação Dose-Resposta a Droga , Glutationa/metabolismo , Hipocampo/efeitos dos fármacos , Rim/efeitos dos fármacos , Masculino , Camundongos , Estrutura Molecular , Estresse Oxidativo , Patulina/administração & dosagem , Patulina/químicaRESUMO
AIMS: Epilepsy affects 0.5-1% of the world's population, and approximately a third of these patients are refractory to current medication. Given their ability to proliferate, differentiate and regenerate tissues, stem cells could restore neural circuits lost during the course of the disease and reestablish the physiological excitability of neurons. This study verified the therapeutic potential of bone marrow mononuclear cells (BMMCs) on seizure control and cognitive impairment caused by experimentally induced epilepsy. MAIN METHODS: Status epilepticus (SE) was induced by lithium-pilocarpine injection and controlled with diazepam 90 min after SE onset. Lithium-pilocarpine-treated rats were intravenously transplanted 22 days after SE with BMMCs obtained from enhanced green fluorescent protein (eGFP) transgenic C57BL/6 mice. Control epileptic animals were given an equivalent volume of saline or fibroblast injections. Animals were video-monitored for the presence of spontaneous recurrent seizures prior to and following the cell administration procedure. In addition, rats underwent cognitive evaluation using a Morris water maze. KEY FINDINGS: Our data show that BMMCs reduced the frequency of seizures and improved the learning and long-term spatial memory impairments of epileptic rats. EGFP-positive cells were detected in the brains of transplanted animals by PCR analysis. SIGNIFICANCE: The positive behavioral effects observed in our study indicate that BMMCs could represent a promising therapeutic option in the management of chronic temporal lobe epilepsy.
Assuntos
Transplante de Células , Transtornos Cognitivos/prevenção & controle , Epilepsia/terapia , Transtornos da Memória/prevenção & controle , Monócitos/citologia , Convulsões/prevenção & controle , Animais , Células da Medula Óssea/citologia , Doença Crônica , Transtornos Cognitivos/induzido quimicamente , Diazepam/farmacologia , Modelos Animais de Doenças , Epilepsia/complicações , Lítio/farmacologia , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Transtornos da Memória/induzido quimicamente , Camundongos , Camundongos Endogâmicos C57BL , Monócitos/transplante , Pilocarpina/farmacologia , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , NataçãoRESUMO
OBJECTIVES: To present recent scientific evidence on the effects of stem cell transplantation in animal models of neonatal hypoxic-ischemic brain injury and address the translational relevance of cell therapy for clinical application in this context. SOURCES: The PubMed and Scopus databases were used to select articles. The selection criterion was the specificity of articles regarding the subject studied, preferably articles published from 2000 onward. We also reviewed classic articles from previous years that were applicable to this review. SUMMARY OF THE FINDINGS: Stem cells from different exogenous sources may exhibit neuroprotective properties in experimental models of neonatal hypoxia-ischemia. In most animal experiments, the morphological and functional benefits observed were independent of neural differentiation, suggesting associated mechanisms of action, such as the release of trophic factors and inflammatory modulation. CONCLUSIONS: Based on the experimental studies analyzed, cell therapy may become a promising therapeutic approach in the treatment of children with hypoxic-ischemic encephalopathy. However, further studies are warranted to elucidate potential mechanisms of action of these cells and to define safe and effective clinical strategies.
Assuntos
Modelos Animais de Doenças , Hipóxia-Isquemia Encefálica/cirurgia , Transplante de Células-Tronco/métodos , Pesquisa Translacional Biomédica , Animais , Humanos , Recém-NascidoRESUMO
OBJETIVOS: Apresentar evidências científicas recentes sobre os efeitos do transplante com células-tronco em modelos animais de lesão cerebral hipóxico-isquêmica neonatal e abordar os aspectos translacionais relevantes à aplicação clínica da terapia celular nesse contexto. FONTES DOS DADOS: Para a seleção dos artigos, utilizou-se a base de dados PubMed e Scopus. O critério de seleção de artigos foi a especificidade em relação ao tema estudado, preferencialmente a partir do ano de 2000. Também foram revisados artigos clássicos de anos anteriores que se aplicavam ao propósito desta revisão. SÍNTESE DOS DADOS: Células-tronco de diferentes fontes exógenas podem exibir propriedades neuroprotetoras em modelos experimentais de hipóxia-isquemia neonatal. Na maioria dos experimentos animais, os benefícios morfológicos e funcionais observados foram independentes da diferenciação neural, sugerindo mecanismos de ação associados, tais como a liberação de fatores tróficos e a modulação inflamatória. CONCLUSÕES: Baseado nos estudos experimentais analisados, a terapia celular pode tornar-se uma promissora abordagem terapêutica no tratamento de crianças com encefalopatia hipóxico-isquêmica. No entanto, estudos adicionais necessitam ser realizados a fim de elucidar os possíveis mecanismos de ação dessas células e definir estratégias clínicas seguras e efetivas.
OBJECTIVES: To present recent scientific evidence on the effects of stem cell transplantation in animal models of neonatal hypoxic-ischemic brain injury and address the translational relevance of cell therapy for clinical application in this context. SOURCES: The PubMed and Scopus databases were used to select articles. The selection criterion was the specificity of articles regarding the subject studied, preferably articles published from 2000 onward. We also reviewed classic articles from previous years that were applicable to this review. SUMMARY OF THE FINDINGS: Stem cells from different exogenous sources may exhibit neuroprotective properties in experimental models of neonatal hypoxia-ischemia. In most animal experiments, the morphological and functional benefits observed were independent of neural differentiation, suggesting associated mechanisms of action, such as the release of trophic factors and inflammatory modulation. CONCLUSIONS: Based on the experimental studies analyzed, cell therapy may become a promising therapeutic approach in the treatment of children with hypoxic-ischemic encephalopathy. However, further studies are warranted to elucidate potential mechanisms of action of these cells and to define safe and effective clinical strategies.
Assuntos
Animais , Humanos , Recém-Nascido , Modelos Animais de Doenças , Hipóxia-Isquemia Encefálica/cirurgia , Transplante de Células-Tronco/métodos , Pesquisa Translacional BiomédicaRESUMO
Germinal matrix/intraventricular hemorrhage (GMH/IVH) is a complication that arises in premature infants associated with neurological sequelae. Greater understanding of GMH/IVH is needed to develop therapies, a goal that depends on the existence of appropriate animal models. Towards this goal, we aimed to develop a rodent model of GMH/IVH based on collagenase-induced hemorrhage that exhibits histological and neurological consequences similar to that seen in patients. Male 6-day-old rats were placed on a warming pad and anesthetized with halothane/nitrous oxide delivered by face mask. Uni- or bilateral periventricular injections of 2-µl collagenase (2.0 U) were performed freehand with a needle inserted percutaneously. Sham rats were infused with saline. Early neonatal development, long-term motor and cognitive performances and alterations in brain volume were assessed. Collagenase-based GMH/IVH negatively affected ambulation, surface righting and negative geotaxis outcomes more evidently in bilaterally infused rats, which also presented an early decrease in brain volume, as assessed by the Cavalieri method. In adult animals, a unilateral collagenase infusion produced no significant alteration on forepaw preference. Only bilaterally infused rats presented an impairment of object recognition memory and locomotor deficit. Nevertheless, histological evaluation also demonstrated a persistent brain volume reduction in bilaterally infused rats. Our study provides a pioneering animal model of collagenase-based GMH/IVH, which can be used to evaluate preventive strategies and potential therapeutic interventions for this disorder.
Assuntos
Hemorragia Cerebral/enzimologia , Hemorragia Cerebral/patologia , Ventrículos Cerebrais/enzimologia , Ventrículos Cerebrais/patologia , Colagenases/administração & dosagem , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Colagenases/toxicidade , Modelos Animais de Doenças , Humanos , Masculino , Movimento/efeitos dos fármacos , Movimento/fisiologia , Ratos , Ratos WistarRESUMO
Neonatal hypoxia-ischemia (HI) is an important cause of mortality and morbidity in infants. Human umbilical cord blood (HUCB) is a potential source of cellular therapy in perinatology. We investigated the effects of HUCB cells on spatial memory, motor performance, and brain morphologic changes in neonate rats submitted to HI. Seven-day-old rats underwent right carotid artery occlusion followed by exposure to 8% O(2) inhalation for 2 h. Twenty-four hours after HI, rats received either saline solution or HUCB cells i.v. After 3 wk, rats were assessed using a Morris Water Maze and four motor tests. Subsequently, rats were killed for histologic, immunohistochemical, and polymerase chain reaction (PCR) analyses. HI rats showed significant spatial memory deficits and a volumetric decrease in the hemisphere ipsilateral to arterial occlusion. These deficits and decreases were not significantly attenuated by the injection of HUCB cells. Moreover, immunofluorescence and PCR analysis revealed few HUCB cells located in rat brain. Intravenous administration of HUCB cells requires optimization to achieve improved therapeutic outcomes in neonatal hypoxic-ischemic injury.