Evidence of oligodendrogliosis in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism.

AIMS: Mice and nonhuman primates administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) represent elective experimental models of Parkinsonism, in which degeneration of the nigrostriatal dopaminergic pathway is associated with prominent neuroinflammation, characterized by activated microglia and astrocytes in both substantia nigra (SN) and striatum. To date, it is unknown whether oligodendrocytes play a role in these events. METHODS: We performed a detailed qualitative and quantitative analysis of oligodendrocyte-associated changes induced by acute and chronic MPTP treatment, in the SN and striatum of mice and macaques respectively. Oligodendrocytes were immunolabelled by cell-specific markers and analysed by confocal microscopy. RESULTS: In both experimental models, MPTP treatment induces an increase in oligodendrocyte cell number and average size, as well as in the total area occupied by this cell type per tissue section, accompanied by evident morphological changes. This multifaceted array of changes, herein referred to as oligodendrogliosis, significantly correlates with the reduction in the level of dopaminergic innervation to the striatum. CONCLUSIONS: This event, associated with early damage of the dopaminergic neurone axons and of the complex striatal circuits of which they are part, may result in an important, although neglected, aspect in the onset and progression of Parkinsonism.

Lesion-associated microglia and macrophages mediate corralling and react with massive phagocytosis for debris clearance and wound healing after LPS-induced dopaminergic depletion.

Neuroinflammation contributes to neuronal degeneration in Parkinson's disease (PD). However, how brain inflammatory factors mediate the progression of neurodegeneration is still poorly understood. Experimental models of PD have shed light on the understanding of this phenomenon, but the exploration of inflammation-driven models is necessary to better characterize this aspect of the disorder. The use of lipopolysaccharide (LPS) to induce a neuroinflammation-mediated neuronal loss is useful to induce reliable elimination of dopaminergic neurons. Nevertheless, how this model parallels the PD-like neuroinflammation is uncertain. In the present work, we used the direct LPS injection as a model inductor to eliminate dopaminergic neurons of the substantia nigra pars compacta (SNpc) in rats and reevaluated the inflammatory reaction. High-resolution 3D histological examination revealed that, although LPS induced a reliable elimination of SNpc dopaminergic neurons, it also generated a massive inflammatory response. This inflammation-mediated injury was characterized by corralling, a damaged parenchyma occupied by a vast population of lesion-associated microglia and macrophages (LAMMs) undertaking wound compaction and scar formation, surrounded by highly reactive astrocytes. LAMMs tiled the entire lesion and engaged in long-standing phagocytic activity to resolve the injury. Additionally, modeling LPS inflammation in a cell culture system helped to understand the role of phagocytosis and cytotoxicity in the initial phases of dopaminergic degeneration and indicated that LAMM-mediated toxicity and phagocytosis coexist during LPS-mediated dopaminergic elimination. However, this type of severe inflammatory-mediated injury, and subsequent resolution appear to be different from the ageing-related PD scenario where the architectural structure of the parenchyma is mostly preserved. Thus, the necessity to explore new experimental models to properly mimic the inflammatory compound observed in PD degeneration.

Adenoviral vectors encoding tumor necrosis factor-alpha and FasL induce apoptosis of normal and tumoral anterior pituitary cells.

Our previous work showed that tumor necrosis factor (TNF)-alpha and FasL induce apoptosis of anterior pituitary cells. To further analyze the effect of these proapoptotic factors, we infected primary cultures from rat anterior pituitary, GH3 and AtT20 cells with first-generation adenoviral vectors encoding TNF-alpha, FasL or, as a control, beta-galactosidase (beta-Gal), under the control of the human cytomegalovirus promoter. Successful expression of the encoded transgenes was determined by immunocytochemistry. Although we observed basal expression of TNF-alpha and FasL in control cultures of anterior pituitary cells, fluorescence-activated cell sorting (FACS) cell cycle analysis showed that the overexpression of TNF-alpha or FasL increases the percentage of hypodiploid lactotropes and somatotropes. Nuclear morphology and TUNEL staining revealed that the cells undergo an apoptotic death process. We detected strong immunoreactivity for TNFR1 and Fas in the somatolactotrope cell line GH3. TNF-alpha, but not FasL, was expressed in control cultures of GH3 cells. The infection of GH3 cells with adenovirus encoding TNF-alpha or FasL increased the percentages of hypodiploid and TUNEL-positive cells. TNF-alpha or FasL immunoreactivity was not observed in the corticotrope cell line AtT20. However, adenovirus encoding TNF-alpha or FasL efficiently transduced these cells and increased the percentages of hypodiploid and TUNEL-positive cells. The expression of beta-Gal was detected in all these cultures but did not affect cell viability. In conclusion, these results suggest that death signaling cascades triggered by TNF receptor 1 (TNFR1) and Fas are present in both normal and tumoral pituitary cells. Therefore, overexpression of proapoptotic factors could be a useful tool in the therapy of pituitary adenomas.

Measurement of motor disability in MPTP-treated macaques using a telemetry system for estimating circadian motor activity.

The parkinsonian symptoms of primates after MPTP exposure can be measured by several visual methods (classical motor scores). However, these methods have a subjective bias, especially as regards the evaluation of the motor activity. Computerized monitoring systems represent an unbiased method for measuring the motor disability of monkeys after MPTP administration. In this work the motor activity of monkeys before and after MPTP administration is measured and compared with the activity of a control intact group by means of a telemetry system. A pronounced decrease in motor activity was observed after MPTP administration. These results suggest the monitoring method used is suited for characterizing the motor incapacity and possible improvements following treatments to test different therapies to control Parkinson's disease in MPTP models involving primates.

MPP(+)-induced degeneration is potentiated by dicoumarol in cultures of the RCSN-3 dopaminergic cell line. Implications of neuromelanin in oxidative metabolism of dopamine neurotoxicity.

We have tested the idea that oxidative metabolism of dopamine may be involved in MPTP toxicity using the RCSN-3 cell line derived from the substantia nigra of an adult rat. Treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (10 microM), MPTP combined with 40 microM dicoumarol (an inhibitor of DT-diaphorase) and dicoumarol alone, did not induce toxicity in RCSN-3 cells after 72 h incubation. The lack of toxicity in MPTP-treated RCSN-3 cells may be explained by the fact that they are unable to metabolize MPTP to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridinium ion (MPP+ as determined by HPLC. Incubation for 72 h with 100 microM MPP+ induced a 6.6 +/- 1.4% cell death of RCSN-3 cells compared to 3.5 +/- 0.4 observed in control cells. However, when the cells were treated with 100 microM MPP+ and 40 microM dicoumarol, cell death increased 4-fold compared to that of cells treated solely with MPP+ (27 +/- 2%; P<0.001). Under these conditions, a significant increase in DNA fragmentation (3-fold compared to MPP+ alone; P<0.01) and in calpain activation (P<0.05 compared to control) was evident. The inhibition of DT-diaphorase by dicoumarol supports the idea that oxidative metabolism of dopamine is involved in MPP+ toxicity in RCSN-3 cells.

Neuroprotection of lipoic acid treatment promotes angiogenesis and reduces the glial scar formation after brain injury.

After trauma brain injury, a large number of cells die, releasing neurotoxic chemicals into the extracellular medium, decreasing cellular glutathione levels and increasing reactive oxygen species that affect cell survival and provoke an enlargement of the initial lesion. Alpha-lipoic acid is a potent antioxidant commonly used as a treatment of many degenerative diseases such as multiple sclerosis or diabetic neuropathy. Herein, the antioxidant effects of lipoic acid treatment after brain cryo-injury in rat have been studied, as well as cell survival, proliferation in the injured area, gliogenesis and angiogenesis. Thus, it is shown that newborn cells, mostly corresponded with blood vessels and glial cells, colonized the damaged area 15 days after the lesion. However, lipoic acid was able to stimulate the synthesis of glutathione, decrease cell death, promote angiogenesis and decrease the glial scar formation. All those facts allow the formation of new neural tissue. In view of the results herein, lipoic acid might be a plausible pharmacological treatment after brain injury, acting as a neuroprotective agent of the neural tissue, promoting angiogenesis and reducing the glial scar formation. These findings open new possibilities for restorative strategies after brain injury, stroke or related disorders.

IFN-γ signaling, with the synergistic contribution of TNF-α, mediates cell specific microglial and astroglial activation in experimental models of Parkinson's disease.

To through light on the mechanisms underlying the stimulation and persistence of glial cell activation in Parkinsonism, we investigate the function of IFN-γ and TNF-α in experimental models of Parkinson's disease and analyze their relation with local glial cell activation. It was found that IFN-γ and TNF-α remained higher over the years in the serum and CNS of chronic Parkinsonian macaques than in untreated animals, accompanied by sustained glial activation (microglia and astroglia) in the substantia nigra pars compacta. Importantly, Parkinsonian monkeys showed persistent and increasing levels of IFN-γR signaling in both microglial and astroglial cells. In addition, experiments performed in IFN-γ and TNF-α KO mice treated with MPTP revealed that, even before dopaminergic cell death can be observed, the presence of IFN-γ and TNF-α is crucial for microglial and astroglial activation, and, together, they have an important synergistic role. Both cytokines were necessary for the full level of activation to be attained in both microglial and astroglial cells. These results demonstrate that IFN-γ signaling, together with the contribution of TNF-α, have a critical and cell-specific role in stimulating and maintaining glial cell activation in Parkinsonism.

Nigral degeneration correlates with persistent activation of cerebellar Purkinje cells in MPTP-treated monkeys.

In the present work we analyze the cerebellum of chronic parkinsonian monkeys in order to clarify whether chronic mesencephalic depletion is associated with long term activation of the cerebellar neurons in chronic Parkinsonism. In our study, we observed a persistent activation of Purkinje cells in the cerebellum of chronic parkinsonian macaques, characterized by the expression of c-Fos, which correlated with dopaminergic degeneration. These results are compatible with the results observed in fMRI in Parkinson's disease patients, and may contribute to the understanding of additional alterations in the brain circuitry in Parkinsonism.

IFN-γ signaling, with the synergistic contribution of TNF-α, mediates cell specific microglial and astroglial activation in experimental models of Parkinson's disease.

To through light on the mechanisms underlying the stimulation and persistence of glial cell activation in Parkinsonism, we investigate the function of IFN-γ and TNF-α in experimental models of Parkinson's disease and analyze their relation with local glial cell activation. It was found that IFN-γ and TNF-α remained higher over the years in the serum and CNS of chronic Parkinsonian macaques than in untreated animals, accompanied by sustained glial activation (microglia and astroglia) in the substantia nigra pars compacta. Importantly, Parkinsonian monkeys showed persistent and increasing levels of IFN-γR signaling in both microglial and astroglial cells. In addition, experiments performed in IFN-γ and TNF-α KO mice treated with MPTP revealed that, even before dopaminergic cell death can be observed, the presence of IFN-γ and TNF-α is crucial for microglial and astroglial activation, and, together, they have an important synergistic role. Both cytokines were necessary for the full level of activation to be attained in both microglial and astroglial cells. These results demonstrate that IFN-γ signaling, together with the contribution of TNF-α, have a critical and cell-specific role in stimulating and maintaining glial cell activation in Parkinsonism.

MPTP administration increases plasma levels of acute phase proteins in non-human primates (Macaca fascicularis).

Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the Substantia Nigra pars compacta (SNpc). Parkinsonian patients and animal models of PD show inflammatory phenomena such as microglial activation and cytokine production that could modulate the progression of the disease, since they play a crucial role in the degenerative process. Since acute phase proteins (APPs) are involved in a number of homeostatic alterations and inflammatory processes, we analyzed the levels of APPs in primates before and after treatment with MPTP. A significant increase in C-reactive protein (CRP), serum amyloid A (SAA) and haptoglobin (HP) levels after MPTP treatment. These results demonstrate that MPTP induces a systemic generalized inflammatory reaction after specific dopaminergic neurotoxicity insult, suggesting that the inflammatory process in Parkinsonism may affect other immune-inflammatory responses outside the brain.

Changes in vascularization in substantia nigra pars compacta of monkeys rendered parkinsonian.

The degeneration of nigral dopaminergic neurons in Parkinson's disease is believed to be associated with a glial reaction and inflammatory changes. In turn, local factors may induce changes in vascularization and contribute to neuronal vulnerability. Among these factors, Vascular Endothelial Growth Factor (VEGF) is released in adults under pathological conditions and is thought to induce angiogenesis. In order to determine whether changes in brain vasculature are observed in the affected brain regions in parkinsonism, we quantitatively analysed the VEGF-expressing cells and blood vessels in the substantia nigra of monkeys rendered parkinsonian by MPTP injection and compared the results with those obtained in control monkeys. Using stereological methods, we observed an increase in the number of VEGF-expressing neurons and an increase of the number of blood vessels and their volume occupying the substantia nigra pars compacta of monkeys rendered parkinsonian by chronic MPTP intoxication. These changes in vascularization may therefore modify the neuronal availability of blood nutrients, blood cells or toxic substances and neuronal susceptibility to parkinsonism.

Regulatable gene expression systems for gene therapy applications: progress and future challenges.

Gene therapy aims to revert diseased phenotypes by the use of both viral and nonviral gene delivery systems. Substantial progress has been made in making gene transfer vehicles more efficient, less toxic, and nonimmunogenic and in allowing long-term transgene expression. One of the key issues in successfully implementing gene therapies in the clinical setting is to be able to regulate gene expression very tightly and consistently as and when it is needed. The regulation ought to be achievable using a compound that should be nontoxic, be able to penetrate into the desired target tissue or organ, and have a half-life of a few hours (as opposed to minutes or days) so that when withdrawn or added (depending on the regulatable system used) gene expression can be turned "on" or "off" quickly and effectively. Also, the genetic switches employed should ideally be nonimmunogenic in the host. The ability to switch transgenes on and off would be of paramount importance not only when the therapy is no longer needed, but also in the case of the development of adverse side effects to the therapy. Many regulatable systems are currently under development and some, i.e., the tetracycline-dependent transcriptional switch, have been used successfully for in vivo preclinical applications. Despite this, there are no examples of switches that have been employed in a human clinical trial. In this review, we aim to highlight the main regulatable systems currently under development, the gene transfer systems employed for their expression, and also the preclinical models in which they have been used successfully. We also discuss the substantial challenges that still remain before these regulatable switches can be employed in the clinical setting.

Pituitary adenoma presenting as painful intermittent third nerve palsy.

We report the case of a woman with short nocturnal attacks of peri- and retro-orbital pain, diplopia, ptosis, rhinorrhea and lacrimation of five months evolution. Neurological examination was normal between attacks. The latter presented with partial third nerve palsy, which finally became complete and permanent. Brain CT showed a sellar and supraseller tumor with parasellar extension to the right side. We stress the atypical clinical presentation and evolution of this case, and discuss its pathophysiology.

[Intracranial granuloma as a late complication of subdural hematoma]. / Granuloma intracraneal como complicación tardía de un hematoma subdural.

Complications during subdural hematoma treatment are rare and usually occur soon after its evacuation. We present the clinicopathological and radiological findings of a granuloma that happened as late effect of the drainage of a subdural hematoma (1 year after). The presence of bone wax around the tumor and the finding of empty spaces intracytoplasmatic and extracellular surrounded by inflammatory cells suggest that the bone wax was the cause of the granulomatous process.

Hematoma epidural lumbar crónico espontáneo / Chronic spontaneous lumbar epidural hematoma

Presentamos un caso excepcional de estenosis decanal lumbar con síndrome de cola de caballo por un hematoma crónico espontáneo en el espacio epiduralL2-L3.Se trata de un varón de 53 años que, sin ninguna clase de antecedente patológico relacionado con el problema actual (traumatismos, punciones lumbares, toma de antiagregantes o anticoagulantes), presenta una colección hemática epidural que va comprimiendo progresivamente la cola de caballo. Las pruebas de imagen mostraron una colección polilobulada, bien delimitada, que se interpretó como quiste sinovial. Tras la cirugía (laminectomía descompresiva y evacuación) se confirmó el diagnóstico con estudio histológico. Tras la operación se recuperó por completo la función neurológica

We report an exceptional case of cauda equina syndrome, caused by a chronic epidural hematoma of the lumbar spine, (L2-L3). A 53 year old man without history of trauma, lumbar punctures or antiagregant medication, suffered from progressive back pain and minor motor deficit in the legs. The etiology, MRI, intraoperative findings and microscopical study are presented and discussed. After surgery there was a complete resolution of the clinical picture

Uso de biomateriales con fines neurorregenerativos. Aplicación en modelo experimental de traumatismo craneoencefálico / Use of biomaterials in neural regeneration. Application in an experimental model of head injury

Objetivos: Evaluar el rendimiento de los biomateriales poliméricos basados en ácido hialurónico y su utilidad en el Sistema Nervioso Central, sirviendo como soporte, para la supervivencia y diferenciación celular. Material y Metodos: Con el fin de evaluar la viabilidad de los soportes poliméricos y acanalados, se realizaron experimetos in vitro e in vivo mediante el implante en corteza cerebral de ratas Wistar. Mediante técnicas inmunocitoquímicas e histológicas se procedió al análisis de la viabilidad de los soportes. Resultados: Tras el cultivo pudimos constatar la viabilidad celular sobre los biomateriales, asi como su potencial utilidad para la regeneración in vivo de estructuras vasculares y neurales. Conclusiones: La posibilidad de regenerar estructuras vasculares y neurales a través del implante de biomateriales basados en ácido hialurónico, constituye un avance en la utilización de biomateriales en el Sistema Nervioso Central (AU)

Objetives: To evaluate the performance of polymeric biomaterials based on hyaluronic acid and their usefulness in the central nervous system as support for cell differentiation and survival. Material and methods: With the purpose of assessing the viability of polymeric cannulated scaffolds, in vitro and in vivo experiments were made involving implantation in the Wistar rate brain cortex. Immunocytochemical and histological techniques were used to analyze scaffold viability. Results: Following culture, cell viability on the biomaterials was confirmed, together with the potential usefulness of the latter for the in vivo regeneration of vascular and neural structures. Conclusions: The possibility of regenerating vascular and neural structures through the implantation of biomaterials based on hyaluronic acid constitutes an advance in the use of biomaterials in the central nervous system (AU)

Differential density of blood vessels in the mesencephalon of Macaque brain stem

The blood vessels (BV) of the brain stem show different patterns of development, and nutrient requeriments, metabolism and the activity of the different nuclei of the mesencephalon differ from one nucleus to another. The density of BV indirectly explains the blood flow intensity and physiological activity of the nuclei, and may explain the varying degrees of vulnerability of neurons to pathologies. To ascertain the different vascular densities of the mesencephalic nuclei, in the present work we used stereological methods to measure BV density in the Ventral Tegmental Area (VTA), the Substantia Nigra pars compacta (SNpc), the A8 Catecholaminergic Cell group (A8), the Periaqueductal Grey Matter (PAG) and the Locus Coeruleus (LC) of two intact macaques. The results pointed to a high density of BV in the LC; a low density in the SNpc, and an intermediate density in the VTA, A8 and PAG. These results confirm the high blood metabolism of the LC and suggest that the vulnerability of SNpc neurons may be related to the observed low density of BV (AU)

No disponible