Alzheimer-like cell death after vanadium pentoxide inhalation.

Vanadium (V) toxicity depends on its oxidation state; it seems that vanadium pentoxide (V2O5) is the most toxic to the living cells. It has been reported that oral administration induces changes in motor activity and learning; in rats, I.P. administration increases lipid peroxidation levels in the cerebellum and the concentration of free radicals in the hippocampus and cerebellum. Mice that inhaled V2O5 presented a reduced number of tubulin+ in Leydig and Sertoli cells; it has also been reported that inhaled V2O5 induces loss of dendritic spines, necrosis, and hippocampus neuropil alterations; considering the direct consequence of the interaction of V with cytoskeletal components, makes us believe that V2O5 exposure could cause neuronal death in the hippocampus similar to that seen in Alzheimer disease. This work aimed to determine pyramidal hippocampal CA1 cytoskeletal alterations with Bielschowsky stain in rats exposed to V2O5. Male Wistar rats inhaled 0.02 M of V2O5 one h two times a week for two and six months. We found that rats, which inhaled V2O5 reached 56,57% of dead neurons after six months of inhalation; we recognize strong argyrophilic and collapsed somas and typical flame-shaped in all V-exposed rats hippocampus CA1 compared to controls. We also observe somatodendritic distortions. Axons and dendrites displayed thick dark bands replaced by noticeable thickening and nodosities and the cytoskeleton fibrillary proteins' linear traces. Our findings suggest that V2O5 inhalation induces Alzheimer-like cell death with evident cytoskeletal alterations.

Type 2 diabetes mellitus BALB/c mice are more susceptible to granulomatous amoebic encephalitis: Immunohistochemical study.

Granulomatous amoebic encephalitis (GAE) is a chronic, difficult to resolve infection caused by amphizoic amoebae of the genus Acanthamoeba, which in most cases occurs in immunosuppressed persons or with chronic diseases such as diabetes. In this study, we describe the early events of A. culbertsoni infection of GAE in diabetic mice model. Diabetes was induced in male BALB/c mice, with a dose of streptozotocin (130 mg/kg). Healthy and diabetic mice were inoculated via intranasal with 1 × 106 trophozoites of A. culbertsoni. Then were sacrificed and fixed by perfusion at 24, 48, 72 and 96 h post-inoculation, the brains and nasopharyngeal meatus were processed to immunohistochemical analysis. Invasion of trophozoites in diabetic mice was significantly greater with respect to inoculated healthy mice. Trophozoites and scarce cysts were immunolocalized in respiratory epithelial adjacent bone tissue, olfactory nerve packets, Schwann cells and the epineurium base since early 24 h post-inoculation. After 48 h, trophozoites were observed in the respiratory epithelium, white matter of the brain, subcortical central cortex and nasopharyngeal associated lymphoid tissue (NALT). At 72 h, cysts and trophozoites were immunolocalized in the olfactory bulb with the presence of a low inflammatory infiltrate characterized by polymorphonuclear cells. Scarce amoebae were observed in the granular layer of the cerebellum without evidence of inflammation or tissue damage. No amoebas were observed at 96 h after inoculation, suggesting penetration to other tissues at this time. In line with this, no inflammatory infiltrate was observed in the surrounding tissues where the amoebae were immunolocalized, which could contribute to the rapid spread of infection, particularly in diabetic mice. All data suggest that trophozoites invade the tissues by separating the superficial cells, penetrating between the junctions without causing cytolytic effect in the adjacent cells and subsequently reaching the CNS, importantly, diabetes increases the susceptibility to amoebae infection, which could favor the GAE development.

In vivo CNS infection model of Acanthamoeba genotype T4: the early stages of infection lack presence of host inflammatory response and are a slow and contact-dependent process.

This study was developed in order to describe the early morphological events observed during the invasion of two pathogenic strains of Acanthamoeba (genotype T4); A. castellanii and A. culbertsoni, at the olfactory meatus and cerebral, pulmonary, renal, hepatic and splenic tissues levels, an in vivo invasion study. Histological and immunohistochemical description of the events at 24, 48, 72, and 96 h postintranasal inoculations of BALB/c mice was performed. A. castellanii showed a higher invasion rate than A. culbertsoni, which was only able to reach lung and brain tissue in the in vivo model. The current study supports previous evidence of lack of inflammatory response during the early stages of infection. Acanthamoeba invasion of the CNS and other organs is a slow and contact-dependent process. The early morphological events during the invasion of amoebae include the penetration of trophozoites into different epithelia: olfactory, respiratory, alveolar space, and renal tubule, which resemble the process of amoebae invasion described in corneal tissue. The data suggest that after reaching the nasal epithelium, trophozoites continued invasion, separating and lifting the most superficial cells, then migrating and penetrating between the cell junctions without causing a cytolytic effect on adjacent cells. These results reaffirm the idea that contact-dependent mechanisms are relevant for amoebae of Acanthamoeba genus regardless of the invasion site.

The combination of oral L-DOPA/rimonabant for effective dyskinesia treatment and cytological preservation in a rat model of Parkinson's disease and L-DOPA-induced dyskinesia.

Parkinson's disease is the second most prevalent neurodegenerative disease in the world. Its treatment is limited so far to the management of parkinsonian symptoms with L-DOPA (LD). The long-term use of LD is limited by the development of L-DOPA-induced dyskinesias and dystonia. However, recent studies have suggested that pharmacological targeting of the endocannabinoid system may potentially provide a valuable therapeutic tool to suppress these motor alterations. In the present study, we have explored the behavioral (L-DOPA-induced dyskinesias severity) and cytological (substantia nigra compacta neurons and striatum neuropil preservation) effects of the oral coadministration of LD and rimonabant, a selective antagonist of CB1 receptors, in the 6-hydroxydopamine rat model of Parkinson's disease. Oral coadministration of LD (30 mg/kg) and rimonabant (1 mg/kg) significantly decreased abnormal involuntary movements and dystonia, possibly through the conservation of some functional tyrosine hydroxylase-immunoreactive dopaminergic cells, which in turn translates into a well-preserved neuropil of a less denervated striatum. Our results provide anatomical evidence that long-term coadministration of LD with cannabinoid antagonist-based therapy may not only alleviate specific motor symptoms but also delay/arrest the degeneration of striatal and substantia nigra compacta cells.

Manganese mixture inhalation is a reliable Parkinson disease model in rats.

Manganese (Mn) is an essential trace metal. Regardless of its essentiality, it has been reported that the overexposure causes neurotoxicity manifested as extrapyramidal symptoms similar to those observed in Parkinson disease (PD). Recently, our group reported that mice that inhaled for 5 months the mixture of manganese chloride (MnCl(2)) and manganese acetate Mn(OAc)(3) developed movement abnormalities, significant loss of substantia nigra compacta (SNc) dopaminergic neurons, dopamine depletion and improved behavior with l-DOPA treatment. However, this model has only been characterized in mice. In order to have a well-supported and generalizable model in rodents, we used male Wistar rats that inhaled a mixture of 0.04 M MnCl(2) and 0.02 M Mn(OAc)(3), 1h three times a week for 6 months. Before Mn exposure, animals were trained to perform motor tests (Beam-walking and Single-pellet reaching tasks) and were evaluated each week after the exposure. The mixture of MnCl(2)/Mn(OAc)(3) caused alterations in the motor tests, 75.95% loss of SNc dopaminergic neurons, and no cell alterations in Globus Pallidus or striatum. With these results we conclude that the inhalation of the mixture of Mn compounds is a useful model in rodents for the study of PD.

Time course changes of the striatum neuropil after unilateral dopamine depletion and the usefulness of the contralateral striatum as a control structure.

INTRODUCTION: After unilateral dopamine depletion, some ipsilateral alterations occur and the contralateral structure has been utilized as control. OBJECTIVE: Our aim is to analyse the evolution of the ultrastructural alterations of the ipsilateral and contralateral striata of the 6-hydroxydopamine lesioned rats to demonstrate that the contralateral striatum should not be used as control structure. METHODS: After the surgery and the rotation behavior evaluation, animals were killed from 3 to 120 days after lesioning, and their striata were compared with those of aged rats. RESULTS: The ultrastructural analysis shows increased diameter of the synaptic ending in ipsilateral (since the third day) and contralateral striata (since day 30) and an increase in perforated synaptic contacts. CONCLUSION: Our data suggest that the contralateral striatum should not be taken as control structure at least after 20-30 days after lesioning, as the alterations found here may result in wrong interpretations when comparing with the ipsilateral-lesioned one.

Differences between hippocampus and cerebral cortex in aged rats in an oxidative stress model.

Ozone exposure increases the production of free radicals that causes oxidative stress (OS), a state that also occurs during aging and in neurodegenerative diseases. This study identified ultrastructural alterations produced by OS induced by acute ozone exposure in hippocampus and prefrontal cortex in aged compared with young rats. Animals were exposed to 0.70 ppm ozone for 4 h, and controls to flowing air. After the exposure, the tissues were processed for ultrastructural analysis. Results showed increased ultrastructural alterations in the hippocampus and prefrontal cortex in the aged exposed animals compared with controls. OS enhanced the modifications induced by the aging process in those areas related with learning and memory functions, which are the first where degenerative aging changes are observed.

Análisis ultraestructural comparativo en pacientes con enfermedad de Parkinson y ratas viejas / Ultraestructural comparative analysis between Parkinson disease patients and aged rats

Los pacientes con enfermedad de Parkinson idiopático presentan pérdida neuronal de la sustancia negra parte compacta y la consecuente degeneración de la vía nigroestriatal; por otro lado, se ha reportado que los animales viejos también tienen pérdida de dicha inervación. El objetivo del presente trabajo fue comparar los cambios neurodegenerativos en el neuropilo del núcleo caudado de pacientes parkinsónicos y de animales viejos, con el fin de comparar los cambios que sufre dicho núcleo en los dos procesos degenerativos. En el análisis ultraestructural se utilizaron fragmentos del núcleo caudado de pacientes con enfermedad de Parkinson (n= 4) y de ratas viejas de 36 meses de edad (n= 4), para lo cual se midieron 100 botones presinápticos por caudado y se observó la estructura postsináptica y el número de contactos que establecía el botón con la misma estructura. Los resultados muestran que tanto los pacientes con enfermedad de Parkinson como las ratas viejas presentan un incremento estadisticamente significativo en el tamaño de los botones sinápticos, aumento en el número de contactos axodendríticos y aumento en el número de contactos dobles en comparación con los controles. Los datos indican que los pacientes parkinsónicos presentan alteraciones ultraestructurales similares a las de los animales viejos, alteraciones debidas a la ineficiente inervación dopaminérgica procedente del mesencéfalo, por lo cual se considero que el envejecimiento en animales es un buen modelo para el estudio de la neurodegeneración.