RESUMO
Several types of animal models have been developed to investigate Alzheimer's disease (AD). Okadaic acid (OA), a potent inhibitor of phosphatases 1 and 2A, induces characteristics that resemble AD-like pathology. Memory impairment induced by intra-hippocampal injection of OA has been reported, accompanied by remarkable neuropathological changes including hippocampal neurodegeneration, a paired helical filament-like phosphorylation of tau protein, and formation of ß-amyloid containing plaque-like structures. Rats were submitted to bilateral intrahippocampal okadaic acid-injection (100 ng) and, 12 days after the surgery, behavioral and biochemical tests were performed. Using this model, we evaluated spatial cognitive deficit and neuroglial alterations, particularly astroglial protein markers such as glial fibrillary acidic protein (GFAP) and S100B, metabolism of glutamate, oxidative parameters and alterations in MAPKs. Our results indicate significant hippocampal changes, including increased GFAP, protein oxidation, and phosphorylation of p38(MAPK); and decreases in glutathione content, transporter EAAT2/GLT-1, and glutamine synthetase activity as well as a decrease in cerebrospinal fluid S100B. No alterations were observed in glutamate uptake activity and S100B content. In conclusion, the OA-induced model of dementia caused spatial cognitive deficit and oxidative stress in this model and, for the first time to our knowledge, specific astroglial alterations. Findings contribute to understanding diseases accompanied by cognitive deficits and the neural damage induced by AO administration.
Assuntos
Demência/metabolismo , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Neuroglia/metabolismo , Animais , Transtornos Cognitivos/líquido cefalorraquidiano , Transtornos Cognitivos/complicações , Transtornos Cognitivos/metabolismo , Demência/líquido cefalorraquidiano , Demência/induzido quimicamente , Demência/complicações , Demência/psicologia , Transportador 2 de Aminoácido Excitatório/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Hipocampo/metabolismo , Humanos , Masculino , Microinjeções , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fatores de Crescimento Neural/líquido cefalorraquidiano , Fatores de Crescimento Neural/metabolismo , Ácido Okadáico/administração & dosagem , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/líquido cefalorraquidiano , Proteínas S100/metabolismoRESUMO
BACKGROUND: Inflammatory responses in brain are primarily mediated by microglia, but growing evidence suggests a crucial importance of astrocytes. S100B, a calcium-binding protein secreted by astrocytes, has properties of a neurotrophic or an inflammatory cytokine. However, it is not known whether primary signals occurring during induction of an inflammatory response (e.g. lipopolysaccharide, LPS) directly modulate S100B. METHODS: In this work, we evaluated whether S100B levels in cerebrospinal fluid (CSF) and serum of Wistar rats are affected by LPS administered by intraperitoneal (IP) or intracerebroventricular (ICV) injection, as well as whether primary astrocyte cultures respond directly to lipopolysaccharide. RESULTS: Our data suggest that S100B secretion in brain tissue is stimulated rapidly and persistently (for at least 24 h) by ICV LPS administration. This increase in CSF S100B was transient when LPS was IP administered. In contrast to these S100B results, we observed an increase in in TNFα levels in serum, but not in CSF, after IP administration of LPS. In isolated astrocytes and in acute hippocampal slices, we observed a direct stimulation of S100B secretion by LPS at a concentration of 10 µg/mL. An involvement of TLR4 was confirmed by use of specific inhibitors. However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B. In addition, after 24 h exposure to LPS, we observed a decrease in astrocytic glutathione and an increase in astrocytic glial fibrillary acidic protein. CONCLUSIONS: Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases. Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B.
Assuntos
Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Lipopolissacarídeos/farmacologia , Fatores de Crescimento Neural/líquido cefalorraquidiano , Fatores de Crescimento Neural/metabolismo , Proteínas S100/líquido cefalorraquidiano , Proteínas S100/metabolismo , Animais , Astrócitos/citologia , Células Cultivadas , Córtex Cerebral/citologia , Glutationa/metabolismo , Infusões Intraventriculares , Lipopolissacarídeos/administração & dosagem , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/líquido cefalorraquidianoRESUMO
BACKGROUND: The availability of markers able to provide an early insight related to prognostic and functional outcome of patients with traumatic brain injury (TBI) are limited. OBJECTIVE: The relationship of clinical outcome with CSF neuron-specific enolase (NSE), S100B and glial fibrillary acidic protein (GFAP) levels in patients with severe TBI was investigated. METHODS: Twenty patients with severe TBI (7 days at unit care) and controls were studied. Patients were grouped according to the outcome: (1) nonsurvival (n=5): patients who died; (2) survival A (n=15): CSF sampled between 1st and 3rd day from patients who survived after hospital admission; and (3) survival B (n=7): CSF sampled between 4th and 7th day from patients who survived after hospital admission and were maintained with intraventricular catheter up to 7 days. RESULTS: Up to 3 days, S100B and NSE levels (ng/mL) were significantly elevated in the nonsurvival compared with survival A group (S100: 12.45 ± 5.46 vs 5.64 ± 3.36; NSE: 313.20 ± 45.51 vs 107.80 ± 112.10). GFAP levels did not differ between groups. In the survival B group S100B, GFAP, and NSE levels were still elevated compared with control (4.59 ± 2.19, 2.48 ± 2.55, and 89.80 ± 131.10, respectively). To compare S100B and NSE for the prediction of nonsurvival and survival patients we performed receiver operating characteristic curves. At admission, CSF NSE level predicts brain death more accurately than S100B. CONCLUSION: Early elevations (up to 3 days) of S100B and NSE secondary to severe TBI predict deterioration to brain death. However, this feature was more prominently associated with NSE than S100B.
Assuntos
Biomarcadores/líquido cefalorraquidiano , Lesões Encefálicas/líquido cefalorraquidiano , Proteína Glial Fibrilar Ácida/líquido cefalorraquidiano , Fatores de Crescimento Neural/líquido cefalorraquidiano , Fosfopiruvato Hidratase/líquido cefalorraquidiano , Proteínas S100/líquido cefalorraquidiano , Adulto , Lesões Encefálicas/mortalidade , Ensaio de Imunoadsorção Enzimática , Feminino , Escala de Coma de Glasgow , Humanos , Masculino , Prognóstico , Curva ROC , Subunidade beta da Proteína Ligante de Cálcio S100 , Resultado do TratamentoRESUMO
Although the exact cause of Alzheimer's disease remains elusive, many possible risk factors and pathological alterations have been used in the elaboration of in vitro and in vivo models of this disease in rodents, including intracerebral infusion of streptozotocin (STZ). Using this model, we evaluated spatial cognitive deficit and neurochemical hippocampal alterations, particularly astroglial protein markers such as glial fibrillary acidic protein (GFAP) and S100B, glutathione content, nitric oxide production, and cerebrospinal fluid (CSF) S100B. In addition, prevention of these alterations by aminoguanidine administration was evaluated. Results confirm a spatial cognitive deficit and nitrative stress in this dementia model as well as specific astroglial alterations, particularly S100B accumulation in the hippocampus and decreased CSF S100B. The hippocampal astroglial activation occurred independently of the significant alteration in GFAP content. Moreover, all these alterations were completely prevented by aminoguanidine administration, confirming the neuroprotective potential of this compound, but suggesting that nitrative stress and/or glycation may be underlying these alterations. These findings contribute to the understanding of diseases accompanied by cognitive deficits and the STZ-model of dementia.
Assuntos
Demência , Inibidores Enzimáticos/uso terapêutico , Guanidinas/uso terapêutico , Hipocampo/patologia , Estreptozocina , Análise de Variância , Animais , Comportamento Animal/efeitos dos fármacos , Demência/induzido quimicamente , Demência/patologia , Demência/prevenção & controle , Modelos Animais de Doenças , Proteína Glial Fibrilar Ácida/metabolismo , Glutationa/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Fatores de Crescimento Neural/líquido cefalorraquidiano , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/líquido cefalorraquidianoRESUMO
S100B expression, particularly extracellular S100B, is used as a parameter of glial activation and/or death in several situations of brain injury. Several immunoassays for S100B measurement are available, which differ with regard to specificity, sensitivity, sample application, and, of course, economic costs. We standardized two protocols for S100B measurement (range between 1.9pg and 10ng/mL) in human and rat samples from brain and adipose tissues, blood serum, cerebrospinal fluid, urine and cell culture. Abundance and secretion of this protein in adipose tissue reinforces the caution about its origin in blood serum. Interestingly, S100B recognition was affected by the redox status of the protein. This aspect should be considered in S100B measurement, assuming that oxidized and reduced forms possibly coexist in vivo and the equilibrium can be modified by oxidative stress of physiological or pathological conditions or even by obtaining sample conditions.
Assuntos
Ensaio de Imunoadsorção Enzimática/métodos , Fatores de Crescimento Neural/análise , Neuroquímica/métodos , Neuroglia/química , Proteínas S100/análise , Tecido Adiposo/metabolismo , Adulto , Animais , Astrócitos/metabolismo , Encéfalo/metabolismo , Química Encefálica/fisiologia , Linhagem Celular Tumoral , Células Cultivadas , Feminino , Humanos , Recém-Nascido , Masculino , Fatores de Crescimento Neural/sangue , Fatores de Crescimento Neural/líquido cefalorraquidiano , Neuroglia/metabolismo , Oxirredução , Estresse Oxidativo , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/sangue , Proteínas S100/líquido cefalorraquidianoRESUMO
Pre- and postnatal protein malnutrition (PMN) adversely affects the developing brain in numerous ways, but only a few studies have investigated specific glial parameters. This study aimed to evaluate specific glial changes of rats exposed to pre and postnatal PMN, based on glial fibrillary acidic protein (GFAP) and S100B immunocontents as well as glutamine synthetase (GS), in cerebral cortex, hippocampus, cerebellum and cerebrospinal fluid, on the 2nd, 15th and 60th postnatal days. We found increases in GFAP, S100B and GS in the cerebral cortex at birth, suggesting an astrogliosis. Hippocampus and cerebellum also exhibited this profile at birth. However, a significant interaction between age and diet in postnatal life was observed only in the S100B of the cerebral cortex. No changes in the content of GFAP and S100B and GS activity were found on the 60th postnatal day in malnourished rats. In contrast, following an increase in the levels of S100B in the cerebrospinal fluid, during the early developmental stages, levels remained elevated on the 60th postnatal day. Our data support the concept of astrogliosis at birth, induced by PMN, and involve extracellular-regulated kinase activation. Specific alterations in cerebral cortex emphasize the regional vulnerability of the brain to malnutrition; some alterations were observed only at birth (e.g. GFAP); others were observed on the 2nd and 15th post-natal days (e.g. ERK phosphorylation). Taken together, transient and persistent alterations (e.g. elevated extracellular levels of S100B) suggest some brain damage or a risk of brain diseases in rats exposed to PMN.
Assuntos
Dano Encefálico Crônico/etiologia , Dano Encefálico Crônico/fisiopatologia , Transtornos da Nutrição Fetal/fisiopatologia , Gliose/etiologia , Gliose/fisiopatologia , Deficiência de Proteína/fisiopatologia , Envelhecimento/metabolismo , Animais , Animais Recém-Nascidos , Biomarcadores/análise , Biomarcadores/líquido cefalorraquidiano , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Encéfalo/fisiopatologia , Dano Encefálico Crônico/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Proteína Glial Fibrilar Ácida/líquido cefalorraquidiano , Gliose/metabolismo , Glutamato-Amônia Ligase/líquido cefalorraquidiano , Masculino , Fatores de Crescimento Neural/líquido cefalorraquidiano , Neuroglia/metabolismo , Gravidez , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/líquido cefalorraquidianoRESUMO
1. S100B is a calcium-binding protein that acts as a neurotrophic cytokine and is expressed in the central nervous system, predominantly by astrocytes. At nanomolar concentrations, S100B stimulates neurite outgrowth and glial glutamate uptake, as well as protecting neurons against glutamate excitoxicity. 2. Peripheral S100B concentrations, particularly in the serum and cerebrospinal fluid (CSF), have been used as a parameter of glial activation or death in several physiological and pathological conditions. 3. In the present study, we investigated the effect of anaesthetics (thiopental, ketamine and halothane) on CSF concentrations of S100B, as well as a possible sex dependence, because several studies have suggested astrocytes as putative targets for oestrogen. 4. Higher levels of CSF S100B were found when rats were anaesthetized with thiopental; these levels, independently of anaesthetic, were sex dependent. Conversely, no effect of anaesthetic or sex was observed on serum concentrations of S100B. 5. The increase in CSF concentrations of S100B induced by thiopental was confirmed in non-anaesthetized neonatal rats and cortical astrocyte cultures. 6. Assuming CSF S100B as a marker of development, glial activation or even brain damage, investigations regarding the sex dependence of its concentration may be useful in gaining an understanding of sex variations in the behaviour and the pathological course of, as well as susceptibility to, many brain disorders. The findings of the present study reinforce the sex effect on synaptic plasticity and suggest a sex dependence of neural communication mediated by extracellular S100B without restricting the influence of astrocytes on the developmental phase.
Assuntos
Anestésicos/farmacologia , Astrócitos/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Cisterna Magna/efeitos dos fármacos , Halotano/farmacologia , Ketamina/farmacologia , Fatores de Crescimento Neural/líquido cefalorraquidiano , Proteínas S100/líquido cefalorraquidiano , Tiopental/farmacologia , Animais , Animais Recém-Nascidos , Astrócitos/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Cisterna Magna/metabolismo , Feminino , Masculino , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Fatores SexuaisRESUMO
BACKGROUND: S100B is a calcium-binding protein expressed and secreted by astrocytes; serum and cerebrospinal fluid (CSF) S100B elevation has been proposed as an index of brain damage. However, other tissues are shown to produce this protein and the clinical significance of serum S100B elevation has been discussed. METHODS: We investigated the levels of serum and CSF S100B in fasting Wistar rats. Animals were divided into two groups, control and fasting for 48 h, and S100B levels in serum and CSF were determined by ELISA. S100B secretion in dissociated epididymal fat cells was investigated in the presence of epinephrine. RESULTS: We observed a significant >2-fold increase of S100B levels in serum of fasting rats, without changes in its CSF content. Moreover, we demonstrated in vitro epinephrine stimulated S100B release from fat cells. CONCLUSIONS: Present results reinforce that extracerebral sources of S100B, particularly adipocytes, contribute to its serum levels and support the idea that caution is needed when interpreting serum S100B increase as a clinical marker of brain damage.
Assuntos
Proteínas Secretadas pelo Epidídimo/análise , Jejum/sangue , Jejum/líquido cefalorraquidiano , Fatores de Crescimento Neural/sangue , Fatores de Crescimento Neural/líquido cefalorraquidiano , Proteínas S100/sangue , Proteínas S100/líquido cefalorraquidiano , Animais , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Lesões Encefálicas/sangue , Células Cultivadas , Epididimo/citologia , Epididimo/metabolismo , Epinefrina/farmacologia , Masculino , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Fatores de Tempo , Vasoconstritores/farmacologiaRESUMO
The clinical manifestations of neurocysticercosis (NC) are varied and depend on the number and location of cysts, as well as on the host immune response. Symptoms usually occur in NC when cysticerci enter a degenerative course associated with an inflammatory response. The expression of brain damage markers may be expected to increase during this phase. S100B is a calcium-binding protein produced and released predominantly by astrocytes that has been used as a marker of reactive gliosis and astrocytic death in many pathological conditions. The aim of the present study was to investigate the levels of S100B in patients in different phases of NC evolution. Cerebrospinal fluid and serum S100B concentrations were measured in 25 patients with NC: 14 patients with degenerative cysts (D), 8 patients with viable cysts (V) and 3 patients with inactive cysts. All NC patients, except 1, had five or less cysts. In most of them, symptoms had been present for at least 1 month before sample collection. Samples from 8 normal controls (C) were also assayed. The albumin quotient was used to estimate the blood-brain barrier permeability. There were no significant differences in serum (P = 0.5) or cerebrospinal fluid (P = 0.91) S100B levels among the V, D, and C groups. These findings suggest that parenchymal changes associated with a relatively small number of degenerating cysts probably have a negligible impact on glial tissue.
Assuntos
Fatores de Crescimento Neural/sangue , Fatores de Crescimento Neural/líquido cefalorraquidiano , Neurocisticercose/sangue , Neurocisticercose/líquido cefalorraquidiano , Proteínas S100/sangue , Proteínas S100/líquido cefalorraquidiano , Adolescente , Adulto , Idoso , Animais , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Subunidade beta da Proteína Ligante de Cálcio S100RESUMO
Electroconvulsive therapy is considered one of the most effective treatments of major depression, but controversy still exists on whether it may be brain damaging. The aim of this work was to evaluate the cerebrospinal fluid (CSF) levels of neuron specific enolase (NSE), protein S100B and lactate of rats submitted to acute and chronic models of ECS. Rats were submitted to either one shock (acute) or a series of eight shocks, applied one at every 48 h (chronic). CSF samples were collected at 0, 3, 6, 12, 24, 48 and 72 h after the shock in the acute model and at these same time intervals after the last shock in the chronic model. Both models did not produce significant alterations in the levels of NSE. S100B levels were significantly increased at 6 h in the chronic model (p<0.0001). There was a significant increase in the levels of lactate at 0 h in both models (p<0.001). These results support the proposition that ECS does not produce neural damage, and suggest that the alterations in the levels of S100B and lactate may reflect an astrocytic activity of a protective nature.