RESUMEN
PURPOSE: Correlations between granule cell dispersion (GCD), collateral mossy fiber (MF) sprouting, and hippocampal cell loss were studied to assess the relation between GCD and synaptic reorganization in the dentate gyrus of patients with epilepsy. METHODS: Twenty specimens from patients with medically intractable temporal lobe epilepsy (TLE) were studied along with two control specimens. GCD was considered to be present when the stratum granulosum was wider than 120 microm, the close apposition between the granule cell (GC) soma was lost, and GCs were scattered in the molecular layer (ML). Patterns of MF sprouting were differentiated as wide or narrow according to the area of neo-Timm's staining in the ML. GC loss and volumetric cell-density decreases in the different subfields were assessed. RESULTS: MF sprouting was observed in 16 (80%) and GCD in nine (45%) cases. A significant correlation was found between MF sprouting and cell loss in all the subfields except the cornu Ammonis field 2 (CA2). A wide band of MF sprouting was associated with severe cell loss. Cases with GCD had a wide band of MF sprouting and also a higher degree of cell loss than cases without GCD. CONCLUSION: GCD is associated with a specific pattern of MF sprouting, but cell loss was found to be a major determinant for MF reorganization.
Asunto(s)
Epilepsia del Lóbulo Temporal/diagnóstico , Hipocampo/citología , Fibras Musgosas del Hipocampo/ultraestructura , Neuronas/citología , Adulto , Anciano , Recuento de Células , Colorantes , Giro Dentado/citología , Humanos , Persona de Mediana Edad , Células Piramidales/citologíaRESUMEN
Cell-specific imaging has been proposed to increase the potential of magnetic resonance imaging (MRI) for tissue analysis. The hypothezis of the present work was that following intravenous injection of ultra-small particle iron oxide, a contrast agent that accumulates in mononuclear phagocyte cells, macrophages with iron burden would be detectable by MRI within the central nervous system at sites of inflammatory cellular activity. In experimental autoimmune encephalomyelitis in Lewis rats (in which intense macrophage activity results from both hematogenous macrophages and activated microglia), lesions have been seen by MRI as low signal intensities related to magnetic susceptibility effects induced by iron particles. Electron microscopy has revealed the presence of such particles within the cytoplasm of cells that had the morphological aspect of macrophages. Macrophage activity imaging might increase MRI capability with regard to the in vivo pathophysiological aspects of central nervous system (CNS) diseases and might help in therapeutic trials in the numerous CNS diseases in which macrophages are involved.
Asunto(s)
Encéfalo/patología , Encefalomielitis Autoinmune Experimental/patología , Macrófagos/patología , Imagen por Resonancia Magnética , Animales , Medios de Contraste/administración & dosificación , Dextranos , Femenino , Óxido Ferrosoférrico , Inmunohistoquímica , Hierro , Nanopartículas de Magnetita , Óxidos , Ratas , Ratas Endogámicas Lew , Médula Espinal/patologíaRESUMEN
BACKGROUND AND PURPOSE: Ultrasmall particles of iron oxide (USPIO) constitute a contrast agent that accumulates in cells from the mononuclear phagocytic system. In the CNS they may accumulate in phagocytic cells such as macrophages. The goal of this study was to compare USPIO-enhanced MR images with conventional T2-weighted images and gadolinium-enhanced T1-weighted images in a model of experimental autoimmune encephalomyelitis (EAE). METHODS: Nine rats with EAE and four control rats were imaged at 4.7 T and 1.5 T with conventional T1- and T2-weighted sequences, gadolinium-enhanced T1-weighted sequences, and T2-weighted sequences obtained 24 hours after intravenous injection of a USPIO contrast agent, AMI-227. Histologic examination was performed with hematoxylin-eosin stain, Perls' stain for iron, and ED1 immunohistochemistry for macrophages. RESULTS: USPIO-enhanced images showed a high sensitivity (8/9) for detecting EAE lesions, whereas poor sensitivity was obtained with T2-weighted images (1/9) and gadolinium-enhanced T1-weighted images (0/9). All the MR findings in the control rats were negative. Histologic examination revealed the presence of macrophages at the site where abnormalities were seen on USPIO-enhanced images. CONCLUSION: The high sensitivity of USPIO for macrophage activity relative to other imaging techniques is explained by the histologic findings of numerous perivascular cell infiltrates, including macrophages, in EAE. This work supports the possibility of intracellular USPIO transport to the CNS by monocytes/macrophages, which may have future implications for imaging of human inflammatory diseases.
Asunto(s)
Medios de Contraste , Encefalomielitis Autoinmune Experimental/diagnóstico , Gadolinio , Compuestos Heterocíclicos , Hierro , Imagen por Resonancia Magnética , Compuestos Organometálicos , Óxidos , Animales , Encéfalo/patología , Dextranos , Encefalomielitis Autoinmune Experimental/patología , Femenino , Óxido Ferrosoférrico , Inmunohistoquímica , Macrófagos/patología , Nanopartículas de Magnetita , Ratas , Ratas Endogámicas Lew , Sensibilidad y EspecificidadRESUMEN
BACKGROUND AND PURPOSE: Changes occurring in neuropeptide-Y immunoreactivity after kainic acid injection in rats and their possible consequences on seizure-brain damage were studied. METHODS: First, an intra-hippocampal kainic acid injection was performed (n = 7), inducing an ectopic and bilateral neuropeptide-Y immunoreactivity in mossy fibers. On the side of the injection, this neuropeptide-Y staining was associated with dramatic neuronal loss whereas, in the contralateral hippocampus staining was observed without associated neuronal loss. The CA3 a-b pyramidal cell loss induced by an intra-ventricular kainic acid injection was then compared between a control group (n = 6) and a pre-conditioned group (n = 6) characterized by neuropeptide-Y staining in the mossy fibers obtained by a previous contralateral intra-hippocampal kainic acid injection as described. RESULTS: In the pre-conditioned group, the CA3 a-b pyramidal cell loss was significantly lower (m = 33.5%) than in the control group (m = 86.6%). The neuropeptide-Y inhibiting the pre-synaptic release of glutamate, glutamate-related epileptic-brain damage could be reduced when neuropeptide-Y is expressed by granulated cells. IN CONCLUSION: Seizure-linked plasticity could induce a self-protection phenomenon against excitotoxic lesions possibly partially mediated by de novo neuropeptide-Y mossy fiber expression.
Asunto(s)
Epilepsia/inducido químicamente , Epilepsia/prevención & control , Hipocampo/metabolismo , Ácido Kaínico , Neuropéptido Y/metabolismo , Animales , Recuento de Células/efectos de los fármacos , Hipocampo/efectos de los fármacos , Inmunohistoquímica , Fibras Musgosas del Hipocampo/efectos de los fármacos , Fibras Musgosas del Hipocampo/metabolismo , Plasticidad Neuronal/efectos de los fármacos , Neuropéptido Y/fisiología , Células Piramidales/efectos de los fármacos , Células Piramidales/metabolismo , Ratas , Ratas WistarRESUMEN
This study was designed to assess the capacity of several doses of pentoxifylline to prevent or treat chronic-relapsing-EAE (CR-EAE) exacerbations induced in the Lewis rat. Pentoxifylline (PTX) is a methylxanthine derivative that inhibits the production of TNF-alpha, a cytokine involved in EAE and multiple sclerosis physiopathology. Three blind placebo-controlled randomized studies were performed in respectively 40, 30 and 18 rats: a trial of different (PTX) dosages (8, 30, 50, 100 and 200 mg/kg) versus placebo to prevent EAE onset; a trial of PTX (8, 30 or 50 mg/kg) versus placebo to prevent 2 attacks of EAE and a trial of PTX (100 mg/kg) versus placebo to abrogate ongoing clinical EAE. No statistically significant difference was observed between groups in any trial. PTX was ineffective to prevent or treat CR-EAE in these studies.
Asunto(s)
Encefalomielitis/tratamiento farmacológico , Pentoxifilina/uso terapéutico , Vasodilatadores/uso terapéutico , Animales , Enfermedades Autoinmunes/tratamiento farmacológico , Enfermedades Autoinmunes/patología , Tronco Encefálico/patología , Cerebelo/patología , Relación Dosis-Respuesta a Droga , Encefalomielitis/patología , Femenino , Distribución Aleatoria , Ratas , Recurrencia , Médula Espinal/patologíaRESUMEN
Granule cells of the dentate gyrus can express neuropeptide-Y (NPY) in several models of epilepsy involving limbic seizures, however, the nature of this ectopic expression is not well understood at present. We have studied the expression of NPY-immunoreactivity in mossy fibres contralateral to a unilateral intrahippocampal injection of kainic acid and report that ectopic mossy fibre NPY-immunoreactivity is observed throughout the contralateral hippocampus.
Asunto(s)
Agonistas de Aminoácidos Excitadores/farmacología , Hipocampo/química , Ácido Kaínico/farmacología , Neuropéptido Y/inmunología , Animales , Especificidad de Anticuerpos , Epilepsia/fisiopatología , Hipocampo/citología , Hipocampo/efectos de los fármacos , Inmunohistoquímica , Masculino , Microinyecciones , Neuropéptido Y/análisis , Ratas , Ratas WistarRESUMEN
In order to study the localization of methionine in rat brain, an immunological approach was developed by raising antibodies directed against this amino acid. Methionine was conjugated to bovine serum albumin (BSA) or human serum albumin (HSA) via glutaraldehyde. The conjugates were then reduced by sodium borohydride and injected alternately into rabbits. Antibody affinity and specificity were evaluated using an adapted ELISA method, by competition experiments between conjugated methionine and related conjugated compounds, pre-incubated with anti-methionine antibodies diluted at 1/20,000. The resulting cross-reactivity ratios, calculated at half-displacement, showed that glutaraldehyde-methionine conjugate (methionine-G-BSA) was the best recognized compound. Non-reduced methionine conjugate (methionine=G=BSA) and the related-conjugated molecules such as homocysteine, homocysteic acid, cysteine, cystathionine and glutamate were not recognized at all. Antibodies to methionine were directed against a glutaraldehyde-methionine epitope and their very high affinity and specificity made them reliable tools for molecular detection of methionine in rat brain. Using purified antibodies diluted at 1/20,000, motoneurons were found to be the most methionine-immunoreactive cell bodies in glutaraldehyde-fixed rat brain sections.
Asunto(s)
Anticuerpos/inmunología , Metionina/farmacología , Animales , Encéfalo , Ensayo de Inmunoadsorción Enzimática , Glutaral , Inmunohistoquímica , Metionina/inmunología , Neuronas Motoras , Conejos , RatasRESUMEN
The effect of subthalamic nucleus (STh) lesion on apomorphine-induced rotational behaviour and unit activity of substantia nigra pars reticulata (SNr) neurons was studied in normal, sham-control and unilateral 6-OHDA-lesioned rats [SN pars compacta (SNc)-lesioned]. In the latter, contraversive rotational behaviour was greatly reduced by an additional ipsilateral STh lesion. A moderate ipsiversive rotation was observed in rats with a single STh lesion. Concurrently, SN unit extracellular recordings were performed in age-matched normal rats, sham-controls for both lesions, STh-lesioned rats, SNc-lesioned rats, and SNc-lesioned rats with an ipsilateral STh lesion (SNc+STh-lesioned). Pars reticulata neurons had a higher mean firing rate in SNc-lesioned rats than in control rats. Furthermore, 68% of SNr neurons in SNc-lesioned rats had a tonic discharge pattern (against 92.3% in control rats) and 32% a mixed or bursting pattern. After STh lesion, a clear decrease in SNr firing rate was observed in SNc-lesioned rats. Moreover, STh lesion improved interspike interval regularity and decreased the occurrence of bursting patterns. In rats with a single STh lesion, the firing rate was no different from that of the sham-controls but the discharge pattern was more regular. These data show that STh lesion decreased apomorphine-induced rotational behaviour in dopamine-depleted animals. This effect could be related to the suppression of the excitatory effect of STh efferents on the SNr neurons. STh lesion both counterbalanced the increased activity of SNr neurons and regularized their discharge pattern.
Asunto(s)
Apomorfina/farmacología , Movimiento/efectos de los fármacos , Oxidopamina/farmacología , Sustancia Negra/efectos de los fármacos , Tálamo/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Electrofisiología , Masculino , Ratas , Ratas WistarRESUMEN
Reduced glutathione was conjugated to carrier proteins with glutaraldehyde. Conjugates were reduced by sodium borohydride and injected into rabbits. Using an enzyme-linked immunosorbent assay, antibody affinity and specificity were determined by competition experiments between glutathione conjugate and related conjugated compounds. The resulting cross-reactivity ratios, calculated at half-displacement, showed that conjugated glutathione was the best recognized compound. Non-reduced glutathione conjugate was 50 x less recognized. The other related conjugates were not recognized at all. Thus, the high affinity and relative specificity make these antibodies potentially valuable tools for immunohistochemical detection of reduced glutathione in glutaraldehyde-fixed rat brain. Using purified antisera diluted at 1/5000, reduced glutathione was preferentially visualized in nerve fibers of cortex, cerebellum and spinal cord. These results suggest that concentration of GSH in rat CNS are higher in nerve fibers than in neuronal perikaryons.
Asunto(s)
Anticuerpos/inmunología , Glutatión/inmunología , Animales , Encéfalo/metabolismo , Reacciones Cruzadas , Ensayo de Inmunoadsorción Enzimática , Femenino , Glutaral , Inmunohistoquímica/métodos , Masculino , Conejos , Ratas , Ratas Sprague-Dawley , Médula Espinal/metabolismo , Distribución TisularRESUMEN
The relationship between free radicals reactions and the cell detoxifying system was investigated during the development of brain edema following a cryogenic lesion in the rabbit cerebral cortex. The amount of TBA-reactive material present six hours after freezing was less than in the controls, then increased at 48 and 96 hours. The activity of superoxide dismutase (SOD) decreased 6 hours post-injury; at the same time, we observed a stimulation of catalase activity. The glutathione peroxidase activity (GSH-Px) rose 96 hours post-lesion. The decrease of TBA-reactive products could result from an elimination rate that exceeds generation.