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.

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.

Bilateral increase of perforated synapses after unilateral dopamine depletion.

In recent years attention has been focused on perforated synapses considering their possible involvement in synaptic plasticity in the nervous system. It has been hypothesized that an increase in the number of synapses may represent a structural basis for the enduring expression of synaptic plasticity during some events that involve memory and learning; also it has been suggested that perforated synapses increase in number after some experimental situations. The aim of this study was to analyze whether the dopamine depletion produces changes in the synaptology of the corpus striatum of rats after the unilateral injection of 6-OHDA. The findings suggest that after the lesion, both contralateral and ipsilateral striata present a significant increment in the number of perforated synapses, suggesting brain plasticity that might be an intent to recuperate the contact surface lost after endogenous or exogenous aggressions.

Bromocriptine treatment in a murine Parkinson's model: ultrastructural evaluation after dopaminergic deafferentation.

The objective of this article was to identify the effects of bromocriptine on the ultrastructure of the caudate nucleus in rats with a 6-hydroxidopamine (6-OHDA) unilateral lesion of the substantia nigra pars compacta. Eighteen Wistar male rats were stereotactically lesioned with 6-OHDA (n=12), or sham lesioned (n=6). Two days after rotational behavior was tested, and 2 days later, 6 rats were treated with 0.3 mg/Kg bromocriptine orally for a month and 6 rats were kept for the same time without treatment. The neuropile of the sham operated and bromocriptine-treated rats was well preserved contrary to the non-bromocriptine-treated rats. Also, it was found that there was a significant difference in the number of synaptic endings with edema in caudate of bromocriptine-treated rats compared with non-treated rats; however, the size of the synaptic endings were different to those found in the sham lesioned rats. Also, as in the sham lesioned group, the bromocriptines showed more synaptic contacts with dendritic spines contrasting to the non-treated group. The results suggest that bromocriptine possesses antioxidant properties because it decreased the ultrastructural alterations after 6-OHDA lesion.