Oxidative stress in rats experimentally infected by Sporothrix schenckii.

The aim of this study was to evaluate whether oxidative stress occurs in rats experimentally infected by Sporothrix schenckii, and its possible effect on disease pathogenesis. Thirty rats were divided into two groups: the group A (uninfected, n = 18) and the group B (infected by S. schenckii, n=21). Blood samples were collected on days 15, 30 and 40 post-infection (PI). At each sampling time, six rats of the group A, and seven of the group B were bled. TBARS (thiobarbituric acid reactive substances) levels in serum samples were measured to evaluate lipid peroxidation. In addition, catalase (CAT) and superoxide dismutase (SOD) activities, known as biomarkers of antioxidants levels, were verified in whole blood. Seric pro-inflammatory cytokine levels were measured (IFN-γ, TNF-α, and IL-6), which showed that these inflammatory mediators were at higher levels in the infected rats (P < 0.001). In comparison to uninfected animals, rats with sporotrichosis showed significantly higher (p < 0.01) levels of TBARS on day 40 PI; CAT activity was significantly increased (p < 0.01) on days 30 and 40 PI; and SOD activity was increased (p < 0.01) on day 40 PI. Infected rats showed larger testicles and granulomas in the testicular capsule, as well as hepatic granulomas and splenic follicular hyperplasia. All tissues (testicle, spleen, and liver) showed inflammation associated with numerous fungal structures. These results demonstrated that the intense inflammatory response (seric and tissue) in sporotrichosis is a likely mechanism for redox imbalance, and consequently cause the oxidative stress in experimentally infected rats.

Vascular Endothelial Growth Factor Up-regulation in Human Amniotic Fluid Stem Cell Enhances Nephroprotection After Ischemia-Reperfusion Injury in the Rat.

OBJECTIVE: To evaluate if the up-regulation of vascular endothelial growth factor strengthens the protective effect of amniotic fluid stem cells in a renal ischemia-reperfusion injury model. DESIGN: Randomized animal study. SETTINGS: University research laboratory. SUBJECTS: A total of 40 males 12-week-old Wistar rats were subjected to ischemia-reperfusion and assigned to four groups: amniotic fluid stem cells, vascular endothelial growth factor-amniotic fluid stem cells in two different doses, and vehicle. Ten animals were used as sham-controls. INTERVENTION: Six hours after induction of renal ischemia-reperfusion injury, amniotic fluid stem cells, vascular endothelial growth factor-amniotic fluid stem cells in two different doses, or vehicle were injected intraarterially. MEASUREMENTS AND MAIN RESULTS: Analyses were performed at 24 hours, 48 hours, and 2 months after treatment. Outcome measures included serum creatinine, urine microprotenuira, and immunohistomorphometric analyses. Vascular endothelial growth factor-amniotic fluid stem cells induced a significantly higher nephroprotection than amniotic fluid stem cells. This effect was mediated mainly by immunomodulation, which led to lower macrophage infiltration and higher presence of regulatory T cell after ischemia-reperfusion injury. At medium term, it inhibited the progression toward chronic kidney disease. Vascular endothelial growth factor-amniotic fluid stem cells can worsen the ischemia-reperfusion injury when delivered in a high dose. CONCLUSIONS: Up-regulation of vascular endothelial growth factor enhances the therapeutic effect of human amniotic fluid stem cells in rats with renal ischemia-reperfusion injury, mainly by mitogenic, angiogenic, and anti-inflammatory mechanisms.

Cholinergic enzymes and inflammatory markers in rats infected by Sporothrix schenckii.

The aim of this study was to evaluate the cholinesterase activity in serum, whole blood, and lymphocytes, as well as to verify its relation to immune response in rats experimentally infected by Sporothrix schenckii. For this study, 63 Wistar rats (Rattus norvegicus), male, adult were divided into three groups: the negative control group (GC: n = 21), the group infected subcutaneously (GSC: n = 21), and the group infected intraperitoneally (GIP: n = 21). The groups were divided into subgroups and the following variables were evaluated at 15, 30, and 40 days post-infection (PI): acetylcholinesterase (AChE) activity in lymphocytes and whole blood, butyrylcholinesterase (BChE) activity in serum, cytokines levels (IL-1, IL-6, TNFα, and INF-γ), immunoglobulins levels (IgA, IgG, IgM, and IgE), and protein profile by electrophoresis. Both infected groups showed increased levels of inflammatory parameters (P < 0.05) in tissue and inflammatory infiltrates. The activities of AChE in lymphocytes and BChE in serum increased (P < 0.05) significantly in animals from the GSC group on day 40 PI compared to the GC group. Regarding the GIP, there was a marked increase in the AChE activity in lymphocytes on days 30 and 40 PI, and in whole blood on days 15, 30, and 40 PI compared to GC. Furthermore, IL-10, an anti-inflammatory cytokine, was also present in high levels during chronic systemic S. schenckii infections in animals. Therefore, it is concluded that cholinesterase has an important modulatory role in the immune response during granulomatous infection by S. schenckii.

Functional and regenerative effects of local administration of autologous mononuclear bone marrow cells combined with silicone conduit on transected femoral nerve of rabbits.

The inoculation of cells into injury sites can accelerate and improve the quality of nerve regeneration. This study aimed to evaluate the functional and regenerative effects of mononuclear autologous bone marrow cells (MABMC) combined with silicon conduit grafting in rabbit femoral nerves. Twenty-eight animals were allocated to one of two groups: treatment group (TG) or control group (CG), divided according to the time of evaluation, at either 50 or 75 days. After neurotmesis of the femoral nerve, surgical repair was performed with nerve autografts in silicon conduits, leaving a 5mm gap in both groups. The TG received MABMC in silicon conduits, and CG received a sham saline inoculum. Histological, clinical and electrophysiological analyses detected no differences between groups, but analysis of leg diameter showed that TG diameters were larger. This cell therapy did not improve regeneration of the femoral nerve, but there was a tendency for better functional recovery.

Amniotic Fluid Derived Stem Cells with a Renal Progenitor Phenotype Inhibit Interstitial Fibrosis in Renal Ischemia and Reperfusion Injury in Rats.

OBJECTIVES: Mesenchymal stem cells derived from human amniotic fluid (hAFSCs) are a promising source for cellular therapy, especially for renal disorders, as a subpopulation is derived from the fetal urinary tract. The purpose of this study was to evaluate if hAFSCs with a renal progenitor phenotype demonstrate a nephroprotective effect in acute ischemia reperfusion (I/R) model and prevent late stage fibrosis. METHODS: A total of 45 male 12-wk-old Wistar rats were divided into three equal groups;: rats subjected to I/R injury and treated with Chang Medium, rats subjected to I/R injury and treated with hAFSCs and sham-operated animals. In the first part of this study, hAFSCs that highly expressed CD24, CD117, SIX2 and PAX2 were isolated and characterized. In the second part, renal I/R injury was induced in male rats and cellular treatment was performed 6 hours later via arterial injection. Functional and histological analyses were performed 24 hours, 48 hours and 2 months after treatment using serum creatinine, urine protein to creatinine ratio, inflammatory and regeneration markers and histomorphometric analysis of the kidney. Statistical analysis was performed by analysis of variance followed by the Tukey's test for multiple comparisons or by nonparametric Kruskal-Wallis followed by Dunn. Statistical significance level was defined as p <0.05. RESULTS: hAFSCs treatment resulted in significantly reduced serum creatinine level at 24 hours, less tubular necrosis, less hyaline cast formation, higher proliferation index, less inflammatory cell infiltration and less myofibroblasts at 48 h. The treated group had less fibrosis and proteinuria at 2 months after injury. CONCLUSION: hAFSCs contain a renal progenitor cell subpopulation that has a nephroprotective effect when delivered intra-arterially in rats with renal I/R injury, and reduces interstitial fibrosis on long term follow-up.

Glial cells of the central nervous system of Bothrops jararaca (Reptilia, Ofidae): an ultrastructural study / Células gliais do sistema nervoso central de Bothrops jararaca (Reptilia, Ofidae): um estudo ultraestrutural

Although ultrastructural characteristics of mature neuroglia in the central nervous system (CNS) are very well described in mammals, much less is known in reptiles, especially serpents. In this context, two specimens of Bothrops jararaca were euthanized for morphological analysis of CNS glial cells. Samples from telencephalon, mesencephalon and spinal cord were collected and processed for light and transmission electron microscopy investigation. Astrocytes, oligodendrocytes, microglial cells and ependymal cells, as well as myelin sheaths, presented similar ultrastructural features to those already observed in mammals and tended to maintain their general aspect all over the distinct CNS regions observed. Morphological similarities between reptilian and mammalian glia are probably linked to their evolutionary conservation throughout vertebrate phylogeny...

Muito embora as características ultraestruturais da neuróglia madura do sistema nervoso central (SNC) sejam bem descritas em mamíferos, muito pouco é conhecido em répteis, especialmente em serpentes. Neste contexto, dois espécimes de Bothrops jararaca foram eutanasiados para análise morfológica das células gliais presentes no SNC. Amostras de telencéfalo, mesencéfalo e medula espinhal foram coletadas e processadas para investigação por microscopia de luz e eletrônica de transmissão. Astrócitos, oligodendócitos, células microgliais e ependimárias, bem como bainhas de mielina, apresentaram características ultraestruturais similares àquelas já observadas em mamíferos e tenderam a manter seu aspecto geral pelas diferentes regiões observadas no SNC. Similaridades morfológicas entre as células gliais de mamíferos e de répteis estão provavelmente ligadas a sua conservação evolutiva ao longo da filogenia dos vertebrados...

Neuroprotective role of quercetin in locomotor activities and cholinergic neurotransmission in rats experimentally demyelinated with ethidium bromide.

AIM: The purpose of this study was to investigate whether the flavonoid quercetin can prevent alterations in the behavioral tests and of cholinergic neurotransmission in rats submitted to the ethidium bromide (EB) experimental demyelination model during events of demyelination and remyelination. MAIN METHODS: Wistar rats were randomly distributed into four groups (20 animals per group): Control (pontine saline injection and treatment with ethanol), Querc (pontine saline injection and treatment with quercetin), EB (pontine 0.1% EB injection and treatment with ethanol), and EB+Querc (pontine 0.1% EB injection and treatment with quercetin). The groups Querc and Querc+EB were treated once daily with quercetin (50mg/kg) diluted in 25% ethanol solution (1ml/kg) and the animals of the control and EB groups were treated once daily with 25% ethanol solution (1ml/kg). Two stages were observed: phase of demyelination (peak on day 7) and phase of remyelination (peak on day 21 post-injection). Behavioral tests (beam walking, foot fault and inclined plane test), acetylcholinesterase (AChE) activity and lipid peroxidation in pons, cerebellum, hippocampus, hypothalamus, striatum and cerebral cortex were measured. KEY FINDINGS: The quercetin promoted earlier locomotor recovery, suggesting that there was demyelination prevention or further remyelination velocity as well as it was able to prevent the inhibition of AChE activity and the increase of lipidic peroxidation, suggesting that this compound can protect cholinergic neurotransmission. SIGNIFICANCE: These results may contribute to a better understanding of the neuroprotective role of quercetin and the importance of an antioxidant diet in humans to provide benefits in neurodegenerative diseases such as MS.

Oxidative stress parameters in blood, liver, and kidney of diabetic rats treated with curcumin and/or insulin.

This study evaluated the effects of curcumin and/or insulin on antioxidant enzyme activity in blood, liver, and kidney, as well as on lipid peroxidation and delta aminolevulinic dehydratase (δ-ALA-D) activity, and a histopathological analysis of streptozotocin-induced diabetic rats. The animals were divided into six groups (n = 6): control/saline (C); control/curcumin (CCur); diabetic/saline (D); diabetic/insulin (DIns); diabetic/curcumin (DCur); and diabetic/insulin/curcumin (DInsCur). After 30 days of treatment with curcumin and/or insulin, the animals were sacrificed and the liver, kidney, and serum were used for experimental determinations. Results of histopathological analysis showed that the treatment with insulin ameliorate renal and hepatic lesions from both DIns and DInsCur groups. TBARS levels were significantly increased in serum, liver, and kidney in D group and the administration of curcumin and insulin prevented this increase in DIns and DCur groups. The activities of catalase (CAT), superoxide dismutase, and δ-ALA-D presented a significant decrease in the liver and kidney D group when compared to C group (P < 0.05). The animals treated with curcumin and insulin presented an increase of CAT activity, revealing a positive interaction between both substances. The treatments with curcumin or insulin prevented oxidative stress in blood, through modulation of enzymatic antioxidant defenses. These findings contributed to the comprehension that antioxidants from medicinal plants could be used as adjuvant in the treatment of this endocrinopathy and not as single therapy.

Clinical signs and histopathology of brain, spinal cord and muscle of the pelvic limb of rats experimentally infected with Trypanosoma evansi.

The aim of this study was to investigate whether rats infected with Trypanosoma evansi had neurological and locomotor signs, as well as histological lesions in the central nervous system (CNS) and pelvic muscles. To carry out this study, 52 rats were used and divided into two groups. The animals in Group A (n=40) were infected with T. evansi, and the rats in Group B (n=12) were used as negative controls (non-infected). Neurological examination was performed at Days 5, 15, 30 and 150 post-infection (PI) with eventual euthanasia of the rats. Samples of brain, spinal cord and skeletal muscle (biceps femoris and gastrocnemius muscles) were collected. The neurological tests evaluated motor capacity, balance and pain sensitivity. At Day 5 PI in Subgroup A1, the rats showed high parasitemia, became apathetic and presented with slow movements and signs of disorientation. After Day 15 PI in Subgroup A2 and Day 30 PI in Subgroup A3, no more clinical abnormalities were observed. Histologically, there was no damage to the CNS in these three subgroups, but within Subgroup A3, mononuclear infiltration of the muscle was observed. Rats chronically infected (Subgroup A4 - Day 150 PI) showed muscle atrophy, walking dysfunction and paralysis of the hind limbs. Mild mononuclear inflammatory infiltrates and perivascular cuffs were observed in the CNS of some of the animals in Subgroup A4. In these rats, severe muscle damage was observed in the skeletal muscle which included atrophy and loss of muscle fibers, multinucleated giant muscle cells, mononuclear myositis, Wallerian degeneration of the innervating fibers and mononuclear inflammatory infiltrate in the perineurium and adipose tissue. Based upon these findings, we conclude that infection by T. evansi in rats leads to muscle damage, which is probably the cause of the paralysis of hind limbs.

Trypanosoma evansi: Ca(2+) ATPase activity and lipid peroxidation in skeletal muscle from rats experimentally infected.

The aim of this study was to evaluate Ca(2+) ATPase activity and the lipid peroxidation in muscles from rats experimentally infected by Trypanosoma evansi and its roles in the muscle pathogenesis in trypanosomosis. Thirty-six rats were divided in two groups. Group A was infected with an isolate from T. evansi and group B was used as a negative control. Group A was divided into three subgroups (A1, A2 and A3), three animals each group, as well as group B (B1, B2 and B3). The collection of samples were performed at days 5 (A1 and B1), 15 (A2 and B2) and 30 (A3 and B3) post-infection (PI) with the purpose of comparison between healthy and infected rats in the course of the disease. The Ca(2+) ATPase enzyme activity was determined in skeletal muscle samples. Muscle tissue lipid peroxidation was determined by TBARS levels, and histopathologically it was investigated a possible damage to the muscle tissue of rats infected with T. evansi. It was observed a significant decrease of Ca(2+) ATPase activity in infected rats compared to not-infected. This enzymatic inhibition was observed at days 5, 15 and 30 PI. A significant increase was observed for TBARS levels in the muscles of infected rats at days 5, 15 and 30 PI. It was not identified any histological alterations for gastrocnemius in rats infected by T. evansi at days 5 and 15 PI. Nevertheless, at day 30 PI it was verified inflammatory infiltrate with mononuclear cells between muscle fibers in three infected rats (50%). T. evansi infections in rats showed a negative correlation between Ca(2+) ATPase and TBARS levels. Based on these results we suggest that the leg weakness and muscle injuries common in infected animals with T. evansi may be related to a reduced activity of Ca(2+) ATPase and oxidative stress.

Schwann cell expression of an oligodendrocyte-like remyelinating pattern after ethidium bromide injection in the rat spinal cord.

Schwann cells are recognized by their capacity of producing single internodes of myelin around axons of the peripheral nervous system. In the ethidium bromide (EB) model of primary demyelination in the brainstem, it is observed the entry of Schwann cells into the central nervous system in order to contribute to the myelin repair performed by the oligodendrocytes that survived to the EB gliotoxic action, being able to even remyelinate more than one axon at the same time, in a pattern of repair similar to the oligodendroglial one. The present study was developed in the spinal cord to observe if Schwann cells maintained this competence of attending simultaneously different internodes. It was noted that, on the contrary of the brainstem, Schwann cells were the most important myelinogenic cells in the demyelinated site and, although rare, also presented the capacity of producing more than one internode of myelin in distinct axons.

Schwann cell expression of an oligodendrocyte-like remyelinating pattern after ethidium bromide injection in the rat spinal cord / Expressão pelas células de Schwann de um padrão de remielinização semelhante ao oligodendroglial após injeção de brometo de etídio na medula espinhal de ratos

Schwann cells are recognized by their capacity of producing single internodes of myelin around axons of the peripheral nervous system. In the ethidium bromide (EB) model of primary demyelination in the brainstem, it is observed the entry of Schwann cells into the central nervous system in order to contribute to the myelin repair performed by the oligodendrocytes that survived to the EB gliotoxic action, being able to even remyelinate more than one axon at the same time, in a pattern of repair similar to the oligodendroglial one. The present study was developed in the spinal cord to observe if Schwann cells maintained this competence of attending simultaneously different internodes. It was noted that, on the contrary of the brainstem, Schwann cells were the most important myelinogenic cells in the demyelinated site and, although rare, also presented the capacity of producing more than one internode of myelin in distinct axons.

As células de Schwann são reconhecidas por sua capacidade de produzir internodos de mielina únicos ao redor de axônios do sistema nervoso periférico. No modelo de desmielinização primária do brometo de etídio (BE) no tronco encefálico, tem sido observada a entrada destas células no sistema nervoso central. Isso pode contribuir para o reparo mielínico desempenhado pelos oligodendrócitos que sobreviveram à ação glitóxica do BE, chegando a remielinizar mais de um axônio ao mesmo tempo, em um padrão de reparo semelhante ao oligodendroglial. O presente estudo foi realizado na medula espinhal para observar se as células de Schwann mantinham esta competência de atender simultaneamente diferentes internodos. Foi observado que, ao contrário do tronco encefálico, as células de Schwann foram as células mielinogênicas mais importantes no sítio de desmielinização induzida pelo BE e, embora raro, também apresentaram a capacidade de produzir mais de um internodo de mielina em axônios distintos.

Morphometric parameters comparisons of the digestive tract of four teleosts with different feeding habits / Comparações de parâmetros morfométricos do trato digestório de quatro teleósteos com diferentes hábitos alimentares

The present study compared some morphometric parameters of the digestive tract of four teleosts with different feeding habits: traira (Hoplias malabaricus, carnivore), silver catfish (Rhamdia quelen, omnivore), hassar (Hoplosternum littorale, omnivore), and grass carp (Ctenopharyngodon idella, herbivore). The digestive tract was removed from fish collected from nature and fixed for some morphometric analyses, such as: intestinal quotient, intestinal area quotient, vilosity height, digestive somatic index, and hepatosomatic index. Grass carp showed the highest values of intestinal quotient and height vilosity. On the other hand, the intestinal area quotient was higher in traira than in the other species. The intestinal quotient can be used to estimate the feeding habit, and the intestinal area quotient, vilosity height and the relationships between digestive tract length and fish weight or digestive tract weight can provide important additional information to analyze the feeding habits.

O presente estudo comparou alguns parâmetros morfométricos do trato digestório de quatro teleósteos com diferentes hábitos alimentares: traira (Hoplias malabaricus, carnivoro), jundiá (Rhamdia quelen, omnivoro), tamoatá (Hoplosternum littorale, omnivoro) e carpa capim (Ctenopharyngodon idella, herbivoro). O trato digestório foi removido dos peixes coletados da natureza e em seguida fixado para algumas análises morfométricas, tais como: quociente intestinal, quociente da área intestinal, altura da vilosidade, índice digestivo somático e índice hepatossomático. Os maiores valores para o quociente intestinal e a altura das vilosidades foram encontrados em carpa capim. Por outro lado, o quociente da área intestinal foi maior na traira do que nas outras espécies. O quociente intestinal pode ser utilizado para estimar o hábito alimentar, e o quociente da área intestinal, a altura da vilosidade e as relações entre o comprimento do trato digestório e o peso do peixe ou peso do trato digestório podem fornecer importantes informações adicionais para analisar o hábito alimentar.

Ethidium bromide-induced demyelination in the sciatic nerve of diabetic rats / Desmielinização induzida pelo brometo de etídio no nervo ciático de ratos diabéticos

This study aims to observe the process of myelin loss and repair following the injection of the gliotoxic agent ethidium bromide (EB) in the sciatic nerve of rats previously induced to diabetes mellitus by streptozotocin. Injection of EB was also done in non-diabetic rats. The animals were euthanatized from 3 to 31 days after intraneural injection and nerve sections were collected for ultrastructural study. In non-diabetic rats, Schwann cells (CS) showed signs of intoxication 3 days after, with cytoplasmic vacuolization and rejection of their myelin sheaths. Myelin debris were removed by macrophages in the endoneurium and mast cells were abundant in the lesions. From 14 days following EB injection, supernumerary CS were seen in the expanded endoneurium as well as thin myelin sheaths indicating remyelination. Diabetic rats presented a more extensive myelin vesiculation and segmentar demyelination, with delayed activities from both macrophages and remyelinating SC. No mast cells were noted.

O estudo visa à observação do processo de perda e reparo mielínico pós-injeção do gliotóxico brometo de etídio (BE) no nervo ciático de ratos previamente induzidos a diabetes mellitus pela estreptozotocina. Injeção de BE foi igualmente realizada em ratos não-diabéticos. Os animais foram eutanasiados dos 3 aos 31 dias pós-injeção intraneural, com colheita de amostras neurais para estudo ultra-estrutural. Nos animais não-diabéticos, as células de Schwann (CS) mostraram sinais de intoxicação a partir dos 3 dias pós-gliotóxico, com vacuolização citoplasmática e rejeição de suas bainhas de mielina. Restos mielínicos eram removidos por macrófagos no interior do endoneuro e mastócitos eram abundantes nas lesões. A partir dos 14 dias, CS supranumerárias foram encontradas no endoneuro expandido, além de finas bainhas de mielina indicativas de remielinização. Os ratos diabéticos apresentaram vesiculação mielínica e desmielinização segmentar mais extensas, bem como ausência de mastócitos e atraso na atividade macrofágica e na função remielinizante das CS.

Remyelination in experimentally demyelinated connexin 32 knockout mice.

The aim of this study was to evaluate the role of connexin 32 (Cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1% ethidium bromide solution or saline in the sciatic nerve of Cx 32 knockout mice. Euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. Within the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. We concluded that the regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other laboratory species. Therefore, these results suggest that absence of Cx 32 did not interfere with the normal pattern of remyelination in this model in young mice.

Remyelination in experimentally demyelinated connexin 32 KnockOut mice / Remielinização em camundongos KnockOut para conexina 32 desmielinizados experimentalmente

The aim of this study was to evaluate the role of connexin 32 (Cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1 percent ethidium bromide solution or saline in the sciatic nerve of Cx 32 knockout mice. Euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. Within the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. We concluded that the regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other laboratory species. Therefore, these results suggest that absence of Cx 32 did not interfere with the normal pattern of remyelination in this model in young mice.

Este estudo visou avaliar o papel da conexina 32 (Cx 32) durante a remielinização no sistema nervoso periférico. Uma injeção local de 0,1 por cento de solução de brometo de etídio foi realizada no nervo ciático de camundongos deletados para a Cx 32, com eutanásia dos animais aos 1, 2, 3, 7, 15, 21 e 30 dias pós-injeção. Avaliações histoquímicas, imunoistoquímicas, por imunofluorescência e por microscopia eletrônica de transmissão foram utilizadas na análise do desenvolvimento das lesões. Nos nervos ciáticos, células de Schwann mostraram inicialmente sinais de intoxicação e rejeitaram suas bainhas. Após sete dias, observaram-se finas bainhas neoformadas, com compactação desigual e alças redundantes (tomácula). Conclui-se que a regeneração de bainhas de mielina perdidas no SNP seguiu o padrão já relatado deste modelo em outras espécies de laboratório. Portanto, estes resultados sugerem que a ausência da Cx 32 não interferiu com o padrão normal de remielinização em camundongos jovens neste modelo.

Effect of vitamin E on ectonucleotidase activities in synaptosomes and platelets and parameters of oxidative stress in rats experimentally demyelinated.

NTPDase and 5'-nucleotidase activities in synaptosomes and platelets and oxidative stress parameters, such as TBARS levels, non-protein thiols and catalase activity were analyzed in rats submitted to demyelination by ethidium bromide (EB) and treated with vitamin E. The following groups were studied: I control (saline); II (canola oil); III (vitamin E); IV (EB) and V (EB and vitamin E). 2mg/kg of vitamin E were injected intraperitoneally in animals from groups III and V for seven days. After this time, the animals were submitted to euthanasia and samples were collected for biochemical assays. The results showed that NTPDase and 5'-nucleotidase activities were significantly increased in synaptosomes and platelets of rats from group IV when compared with the groups I, II, III and V (p<0.05). When demyelinated rats were treated with vitamin E (group V), NTPDase activity in synaptosomes and platelets was reduced to control level, while 5'-nucleotidase activity was significantly increased in relation to the control group (p<0.05). TBARS levels and non-protein thiols were significantly increased in group IV (p<0.05), while catalase activity was significantly decreased in this group when compared with the control group (p<0.05). No differences in TBARS levels, non-protein thiols and catalase activity were observed in groups I, II, III and V. These findings demonstrate that ectonucleotidase activities in synaptosomes and platelets and some parameters of oxidative stress were altered after a demyelinating event on the nervous system and that treatment with vitamin E modulated adenine nucleotide hydrolysis and altered oxidative stress parameters in this experimental condition.

Ethidium bromide-induced demyelination in the sciatic nerve of diabetic rats.

This study aims to observe the process of myelin loss and repair following the injection of the gliotoxic agent ethidium bromide (EB) in the sciatic nerve of rats previously induced to diabetes mellitus by streptozotocin. Injection of EB was also done in non-diabetic rats. The animals were euthanatized from 3 to 31 days after intraneural injection and nerve sections were collected for ultrastructural study. In non-diabetic rats, Schwann cells (CS) showed signs of intoxication 3 days after, with cytoplasmic vacuolization and rejection of their myelin sheaths. Myelin debris were removed by macrophages in the endoneurium and mast cells were abundant in the lesions. From 14 days following EB injection, supernumerary CS were seen in the expanded endoneurium as well as thin myelin sheaths indicating remyelination. Diabetic rats presented a more extensive myelin vesiculation and segmentar demyelination, with delayed activities from both macrophages and remyelinating SC. No mast cells were noted.

Pre-treatment with ebselen and vitamin E modulate acetylcholinesterase activity: interaction with demyelinating agents.

The ethidium bromide (EB) demyelinating model was associated with vitamin E (Vit E) and ebselen (Ebs) treatment to evaluate acetylcholinesterase (AChE) activity in the striatum (ST), hippocampus (HP), cerebral cortex (CC) and erythrocytes. Rats were divided into seven groups: I-Control (saline), II-(canola); III-(Ebs), IV-(Vit E); V-(EB); VI-(EB+Ebs) and VII-(EB+Vit E). At 3 days after the EB injection, AChE activity in the CC and HC was significantly reduced in groups III, IV, V, VI and VII (p<0.05) and in the ST it was reduced in groups III and V (p<0.05) when compared to the control group. At 21 days after the EB injection, AChE activity in the CC was significantly reduced in groups III, IV and V, while in groups VI and VII a significant increase was observed when compared to the control group. In the HC and ST, AChE activity was significantly reduced in groups V, VI and VII when compared to the control group (p<0.05). In the erythrocytes, at 3 days after the EB injection, AChE activity was significantly reduced in groups III, IV, V, VI and VII and at 21 days there was a significant reduction only in groups VI and VII (p<0.05) when compared to the control group. In conclusion, this study demonstrated that Ebs and Vit E interfere with the cholinergic neurotransmission by altering AChE activity in the different brain regions and in the erythrocytes. Furthermore, treatment with Vit E and Ebs protected against the demyelination lesion caused by EB. In this context, we can suggest that ebselen and Vit E should be considered potential therapeutics and scientific tools to be investigated in brain disorders associated with demyelinating events.