Made available in DSpace on 2015-07-22T20:49:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-26 / Objetivo: O objetivo do presente estudo foi avaliar nos ratos a presença dos Movimentos de Patas e dos Movimentos Periódicos das Patas durante o ciclo sono-vigília, em um modelo animal da SPI, induzido pela lesão do núcleo dopaminérgico A11, com a neurotoxina (6-OHDA), reproduzindo assim a característica fenotípica motora da SPI. Métodos: Foram implantados eletrodos nos ratos para os registros eletrocorticográfico e eletromiográfico. As gravações foram monitoradas durante o período claro e escuro, com a duração de 12 horas cada e, foram avaliadas nos dias 7, 15 e 28 após a injeção da 6-hidroxidopamina (Lesão) ou solução salina tamponada (SHAM). Um grupo controle (CTRL), que não recebeu nenhuma droga, também foi incluído no experimento. As porcentagens de vigília (VIG) foram divididas em segmentos de 4 horas no período escuro. Além disto, as porcentagens de Eficiência do Sono (ES), o Sono de Ondas Lentas (SOL), o Sono Paradoxal (SP), a VIG, os Movimentos das Patas (MP) e os Movimentos Períodicos das Patas (MPP) foram avaliados no período claro e escuro. Resultados: Os resultados demonstraram que, como seriam esperados para um modelo animal da SPI, todos os ratos A11 lesionados apresentavam um aumento no percentual da VIG durante o último bloco do período escuro. O grupo Lesão comparado ao grupo CTRL e SHAM apresentaram um aumento das freqüências dos MP e dos MPP, no período claro, principal período de sono dos ratos. Conclusão: A lesão bilateral nos núcleos A11 em ratos, provoca uma alteração na arquitetura do sono e nos resultados eletromiográficos da musculatura das patas, correspondendo assim com características consistentes encontrada na SPI e no MPP em humanos. / Background: Restless Legs Syndrome (RLS) is a major healthcare burden of increasing prevalence. It has been demonstrated that periodic limb movements in sleep (PLM) can occur as an isolated phenomenon, but they are often associated with RLS and represent the only symptom of this disorder that can be measured electrophysiologically. The aim of this study was to examine the sleep–wake behavior and the presence of PLM in a rat model of RLS induced by lesioning the A11 dopaminergic nuclei with the neurotoxin 6-hydroxydopamine (6-OHDA). Methods: Rats were implanted with electrodes for electrocorticography and electromyography. Sleep recordings were monitored during light and dark periods lasting 12 h each and were evaluated on days 7 (L7 group), 15 (L15 group) and 28 (L28 group) after injection of 6-OHDA or PBS (SHAM group). A control (CTRL) group that did not receive any injection was also included in the experiment. Wakefulness (WK) percentages were generated for 4-h segments of the dark period, yielding the following 3 bins: 7 to 11 pm, 11 pm to 3 am and 3 to 7 pm. Additionally, sleep efficiency, slow wave sleep, paradoxical sleep, WK, limb movements (LM) and PLM percentages were evaluated for the entire 12 h of the light and dark phases. Results: The results demonstrated that all the A11-lesioned rats exhibited an increased percentage of WK during the last block of the dark period, as would be expected for an animal model of RLS. In addition, at all time points after A11 lesioning, groups presented increased frequencies of LM and PLM most during light periods. Conclusions: Thus, this model has characteristics strikingly consistent with PLM in humans, including coexistence with RLS symptoms. / TEDE / BV UNIFESP: Teses e dissertações

A Doença de Parkinson (DP) é a segunda doença neurodegenerativa mais comum, afetando em média 2-3% dos indivíduos com idade superior a 65 anos. Além dos sintomas motores altamente debilitantes, os sintomas não-motores podem preceder em muitos anos o aparecimento dos sintomas motores, podendo caracterizar uma fase prodrômica da DP. Uma potencial estratégia farmacológica é a introdução de agentes neuroprotetores no estágio inicial da doença, a fim de prevenir a morte neuronal decorrente do progresso da neurodegeneração. A N-acetilcisteína (NAC) é um antioxidante, anti-inflamatório e modulador glutamatérgico que mostrou vários benefícios terapêuticos em transtornos psiquiátricos. Neste estudo, foi avaliado o efeito da NAC na prevenção dos danos induzidos por 6-Hidroxidopamina (6-OHDA) sobre parâmetros motores, cognitivos e morfológicos em um modelo de DP em larvas de peixes-zebra. Nossos resultados mostraram que NAC foi capaz de prevenir os déficits motores e cognitivos e as alterações morfológicas causadas pela exposição a 6-OHDA, o que reforça a relevância de seus efeitos neuroprotetores. Por atuar em diferentes alvos relevantes na fisiopatologia da DP, NAC é um potencial candidato para prevenção e tratamento de DP. / Parkinson’s disease (PD) is the second most common neurodegenerative disorder, affecting on average 2-3% of the individuals older than 65 years. In addition to its highly debilitating motor symptoms, non-motor symptoms may precede by many years their motor counterparts, which may characterize a prodromal phase of PD. A potential pharmacological strategy is to introduce neuroprotective agents at an earlier stage in order to prevent further neuronal death. N-acetylcysteine (NAC) is an antioxidant, anti-inflammatory and glutamatergic modulator that has shown various therapeutic benefits in brain disorders. In this study, it was evaluated the effect of NAC to prevent the damage induced by 6-OHDA on motor, cognitive and morphological parameters in a PD model in larval zebrafish. NAC was able to prevent the motor and cognitive deficits and morphological alterations caused by exposure to 6-OHDA, which reinforce the relevance of its neuroprotective effects. By acting on different relevant targets in the pathophysiology of PD, NAC is a potential candidate for prevention and treatment of PD.

Orientador: Prof. Dr. Sérgio Bernardo tenório / Co-orientador: Prof. Dr. Joacir Graciolli Cordeiro / Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Clínica Cirúrgica. Defesa: Curitiba, 01/03/2013 / Bibliografia: fls. 93-111 / Resumo: A Doença de Parkinson (PD) é uma doença de grande implicação em saúde pública, pois acomete cerca de 1% da população idosa e gera altos gastos com o tratamento. Atualmente, o tratamento medicamentoso se baseia na combinação de L-3,4- dihidroxifenilalanina (L-DOPA) com agonistas dos receptores dopaminérgicos. A principal desvantagem da terapia medicamentosa é o desenvolvimento de refratariedade e de efeitos colaterais incapacitantes, como discinesia e fenômeno on-off. Modalidades terapêuticas cirúrgicas foram, portanto, desenvolvidas, como técnicas ablativas (talamotomia, palidotomia), estimulação encefálica profunda (EEP) e transplante de células embrionárias dopaminérgicas. Atualmente a EEP é o padrão-ouro no tratamento da PD refratária ao tratamento medicamentoso. É proposto que a modulação do STN (núcleo subtalâmico) restabeleça o equilíbrio na circuitaria dos gânglios da base (GB), diminuido a excitotoxicidade glutamatérgica ao striatum. EEP é uma terapia sintomática, a qual promove uma melhora transitória dos sintomas motores responsivos à dopamina. Por outro lado, o transplante celular oferece uma abordagem tecidual restauradora constituindo uma estratégia promissora no tratamento da PD, por tratar-se de um tratamento possivelmente curativo. Um fator limitante ao uso rotineiro de transplantes neuronais é a baixa taxa de sobrevida das células dopaminérgicas transplantadas. Este estudo investiga o impacto da lesão do STN e/ou da ZI (Zona Incerta), ambas realizadas anteriormente ao transplante de células embrionárias provenientes do mesencéfalo ventral, na taxa de sobrevida das células dopaminérgicas e na resposta funcional motora. Com este objetivo, PD foi induzida pela injeção unilateral de 6-OHDA (6- hidroxidopamina) no feixe prosencefálico medial (FPM) de ratos, os quais foram separados em três grupos. O primeiro grupo foi submetido ao transplante estriatal de células embrionárias. Os outros dois grupos receberam injeção de ácido quinolínico no STN e/ou na ZI onze semanas antes do transplante, causando uma lesão parcial destas estruturas. Um quarto grupo (grupo controle puro), no qual nenhuma intervenção cirúrgica foi realizada, foi utilizado para comparar os efeitos dos procedimentos cirúrgicos com animais intactos. Após cada intervenção cirúrgica, testes comportamentais foram realizados, a fim de isolar o efeito de cada procedimento. Foi observado que no grupo submetido à lesão parcial do STN combinado ao transplante, obteve-se um aumento de 106% na taxa de sobrevida das células transplantadas comparado ao grupo submetido somente ao transplante. O grupo no qual a lesão parcial da ZI foi realizada, a taxa de sobrevida foi aumentada em 147% comparado ao grupo que recebeu o transplante como intervenção única. Adicionalmente, na bateria de testes comportamentais realizada após o transplante, o resultado da rotação induzida por apomorfina e dos testes comportamentais espontâneos foi superior no grupo submetido à lesão parcial do STN quando comparado ao grupo somente transplantado. Estes dados sugerem que a lesão parcial do STN e/ou da ZI possa ter reduzido a excitotoxicidade e logo optimizado o ambiente neuroquímico estriatal, aumentando a taxa de sobrevida das células transplantadas. Apesar de apresentar contagem celular semelhante ao grupo submetido à lesão parcial do STN, os ratos nos quais apenas a ZI foi lesionada não apresentaram melhora significativamente superior ao grupo somente transplantado nos testes comportamentais pós-transplante. Estes dados sugerem a existência de outros mecanismos envolvidos na melhora funcional motora. A combinação da supressão do STN com a terapia celular restauradora se revelou factível e de efeito sinérgico. Hipotetiza-se ser esta uma possível técnica para refinar o manejo da PD. Há necessidade de mais estudos a fim de investigar a aplicabilidade clínica da terapia combinada, incluindo o papel de outros métodos de modulação do STN (e.g. EEP) acoplado ao transplante celular como uma possível abordagem inovadora no tratamento da PD refratária. / Abstract: Parkinson's disease (PD) has a great implication on public health. It affects approximately 1% of the elderly and involves high expenses with its treatment. Currently the drug-based treatment is based in the combination of L-3,4-dihydroxyphenylalanine (L-DOPA) with dopamine receptors agonists. The principal disadvantage of the medical therapy is the development of refractoriness and disabling side-effects, i.e. dyskinesia and on-off phenomenon. Surgical modalities were, therefore, developed, e.g. ablative techniques (thalamotomy, pallidotomy), deep brain stimulation and embryonic dopaminergic cell transplantation. Currently, deep brain stimulation is the gold standard in the treatment of cases refractory to medication. It is proposed that the STN (subthalamic nucleus) modulation restores the equilibrium in the basal ganglia circuitry and reduces the excitotoxic glutamatergic input to the striatum. Deep brain stimulation is a symptomatic therapy, which promotes a transitory improvement of the dopamine-responsive motor symptoms. On the other hand, cell transplantation is a tissue restorative approach and represents a promising strategy in the treatment of PD, since it is a possible curative treatment. A limiting factor to the routine use of neuronal grafts is the poor dopaminergic cell survival. This study investigates the impact of a STN and/or ZI (Zona Incerta) lesion, both performed prior to ventral mesencephalic embryonic cell transplantation in the dopaminergic cell survival and motor functional outcome. For this purpose, unilateral PD was induced by unilateral injection of 6-OHDA (6-hydroxydopamine) into the medial forebrain bundle of rats, which were assigned into three groups. The first group underwent ipsilateral embryonic cell grafting into the striatum. The other two groups received quinolinic acid injection into the STN and/or ZI eleven weeks prior to transplantation, causing a partial lesion of these structures. A forth group (naive control group), in which no surgical intervention was performed, was used to compare the effects of the surgical procedures with intact animals. After each surgical intervention, behavioural tests were performed to isolate the effect of each procedure. It was observed that in the group that received a partial STN lesion combined with the graft, cell survival was boosted in 106% compared to the group that received solely the transplantation. The group in which a partial ZI lesion was performed the cell survival was enhanced in 147% compared to the group with transplantation as single intervention. Moreover, in the behavioural tests after transplantation, the results of apomorphine-induced rotation and spontaneous behavior tests were ameliorated on the STN-lesioned group to a greater extent than on the grafted only group. These data suggest that the STN and/or ZI partial lesion could reduce the excitotoxicity and therefore optimize the striatal neurochemical environment and promote an improvement in cell survival. Despite exhibiting similar cell counting compared to the group that received partial STN lesion, the rats in which only the ZI was lesioned, did not show significant greater improvement in the behavioural tests following transplantation compared to the grafted-only group. This data suggest the existence of other mechanisms involved in motor functional recovery. The combination of STN suppression and cell therapy revealed to be a feasible technique with synergic effect. More studies are required in order to investigate the clinical application of the combined approach including the role of other methods of STN modulation (e.g. deep brain stimulation) coupled to cell transplantation as an innovative approach in the treatment of refractory PD.

The dopaminergic neurodegeneration in the substantia nigra pars compacta (SNpc) is responsible for the marked motor impairment observed in Parkinson's disease (PD). However, the molecular mechanisms underlying this are not completely understood. Since by the time of diagnosis, 50-70% of the dopaminergic neurons of the nigrostriatal pathway have already been degenerated, it is difficult to investigate the early-stage events of disease pathogenesis. Due to inaccessibility of the human brain to study initial pathogenic mechanisms of the disease, experimental models have been developed in an attempt to elucidate PD etiology and its progression. Nevertheless, PD models are a controversial issue in neuroscience research since it is challenging to mimic human neuronal complexity. Therefore, the lack of optimal models that recreate disease pathology is one of the causes of failure of clinical trials that have attempted to find new/better PD therapies. Taking this in consideration, the development of more suitable models is necessary to improve our knowledge regarding PD etiological mechanisms. Additionally, the understanding of the advantages and disadvantages of models already established would also be beneficial for PD research, which our group addressed by reviewing this subject. Considering this, we chose SH-SY5Y cells as a PD model for our studies. To investigate the initial stages of PD-induced neurodegeneration, our work focused in the role of cofilin-1, a protein involved in mitochondrial dysfunction caused by oxidant-induced-apoptosis, which are two pathogenic processes strongly related to PD. Hence, in the thesis, we aimed to validate the use of retinoic-acid-(RA)-differentiated SH-SY5Y cells as an in vitro model and use it to investigate the potential role of cofilin-1 in the initial molecular and cellular mechanisms of PD. Although SH-SY5Y cells are widely used in PD research, their major drawback is their lack of important neuronal features, such as low levels of proliferation and stellate morphology. On the other hand, SH-SY5Y cells can acquire a neuronal phenotype when treated with differentiation agents such as RA. Since several protocols have been described, the consequence of which may be the discrepancies observed among studies regarding neuronal and dopaminergic features. In Chapter I, we aimed to validate a RA-differentiation protocol for SH-SY5Y cells previously established by our research group, focusing upon characterization of neuronal features and its subsequent response to 6-hydroxydopamine (6-OHDA), a toxin widely used to induce dopaminergic degeneration. RA-differentiated SH-SY5Y cells have low proliferative rates, a pronounced neuronal morphology and high expression of genes related to synapse vesicle cycle, dopamine synthesis/degradation, and dopamine transporter (DAT). After exploring phenotypic differences between these two models, we verified that RA-differentiated cells were more sensitive to 6-OHDA toxicity than undifferentiated cells, which could be related to an increase of DAT immunocontent. Many lines of evidence have showed that DAT is responsible for 6-OHDA uptake in vivo. Once inside the neuron, 6-OHDA underwent auto-oxidation causing a significant increase in oxidative stress. However, toxin uptake is not an essential step in undifferentiated SH-SY5Y cells, as auto-oxidation occurs extracellularly. We showed here, for the first time, that RA-differentiated SH-SY5Y cells can mimic, at least in part, an important mechanism of the 6-OHDA-induced cell death found in previous in vivo studies. Hence, the cellular model established by our research group presents essential neuronal features, being a suitable model for PD research. In Chapter II, RA-differentiated SH-SY5Y cells were used as cellular model to investigate disease molecular mechanisms, focusing upon cofilin-1. Our previous data have shown that oxidation of non-phosphorylate (activated) cofilin-1 leads to mitochondrial dysfunction and cell death induced by apoptosis in tumour cells. Here we found that cofilin-1 played a role in early stages of neuronal apoptosis induced by 6-OHDA in our cellular model since cofilin-1 mitochondrial translocation precedes organelle dysfunction. Overexpression of wild type CFL1 resulted in increased sensitivity of SH-SY5Y cells to 6-OHDA-induced neuronal cell death. Furthermore, overexpression of non-oxidizable CFL1 containing Cys-to-Ala mutations (positions 39, 80 and 139) increased neuronal resistance to this toxin, suggesting that oxidation is an important step in 6-OHDA toxicity. Follow-up experiments were performed in order to evaluate clinically whether cofilin-1 pathway proteins content is altered in PD post mortem human brain. Our findings showed a significant decrease in p-cofilin-1/cofilin-1 ratio in PD patients, which indicates an increase in the amount of activated cofilin-1 available for oxidation. Moreover, through principal component analysis, the immunodetection of cofilin-1 pathway proteins were able to discriminate controls and PD individuals during the early-stage of neuropathological changings. Hence, we demonstrated, for the first time, a possible role for cofilin-1 in PD pathogenesis and its potential use as biomarker. Taken together, our data showed that RA-differentiated SH-SY5Y cells present terminally-differentiated dopaminergic neuron features, that are essential to mimic dopaminergic neurons. By using this cellular model and post mortem brain tissue, we also demonstrated a possible role for cofilin-1 in early steps of the neurodegeneration process found in PD, which it could impact drug and biomarker discovery researches.

The dopaminergic neurodegeneration in the substantia nigra pars compacta (SNpc) is responsible for the marked motor impairment observed in Parkinson's disease (PD). However, the molecular mechanisms underlying this are not completely understood. Since by the time of diagnosis, 50-70% of the dopaminergic neurons of the nigrostriatal pathway have already been degenerated, it is difficult to investigate the early-stage events of disease pathogenesis. Due to inaccessibility of the human brain to study initial pathogenic mechanisms of the disease, experimental models have been developed in an attempt to elucidate PD etiology and its progression. Nevertheless, PD models are a controversial issue in neuroscience research since it is challenging to mimic human neuronal complexity. Therefore, the lack of optimal models that recreate disease pathology is one of the causes of failure of clinical trials that have attempted to find new/better PD therapies. Taking this in consideration, the development of more suitable models is necessary to improve our knowledge regarding PD etiological mechanisms. Additionally, the understanding of the advantages and disadvantages of models already established would also be beneficial for PD research, which our group addressed by reviewing this subject. Considering this, we chose SH-SY5Y cells as a PD model for our studies. To investigate the initial stages of PD-induced neurodegeneration, our work focused in the role of cofilin-1, a protein involved in mitochondrial dysfunction caused by oxidant-induced-apoptosis, which are two pathogenic processes strongly related to PD. Hence, in the thesis, we aimed to validate the use of retinoic-acid-(RA)-differentiated SH-SY5Y cells as an in vitro model and use it to investigate the potential role of cofilin-1 in the initial molecular and cellular mechanisms of PD. Although SH-SY5Y cells are widely used in PD research, their major drawback is their lack of important neuronal features, such as low levels of proliferation and stellate morphology. On the other hand, SH-SY5Y cells can acquire a neuronal phenotype when treated with differentiation agents such as RA. Since several protocols have been described, the consequence of which may be the discrepancies observed among studies regarding neuronal and dopaminergic features. In Chapter I, we aimed to validate a RA-differentiation protocol for SH-SY5Y cells previously established by our research group, focusing upon characterization of neuronal features and its subsequent response to 6-hydroxydopamine (6-OHDA), a toxin widely used to induce dopaminergic degeneration. RA-differentiated SH-SY5Y cells have low proliferative rates, a pronounced neuronal morphology and high expression of genes related to synapse vesicle cycle, dopamine synthesis/degradation, and dopamine transporter (DAT). After exploring phenotypic differences between these two models, we verified that RA-differentiated cells were more sensitive to 6-OHDA toxicity than undifferentiated cells, which could be related to an increase of DAT immunocontent. Many lines of evidence have showed that DAT is responsible for 6-OHDA uptake in vivo. Once inside the neuron, 6-OHDA underwent auto-oxidation causing a significant increase in oxidative stress. However, toxin uptake is not an essential step in undifferentiated SH-SY5Y cells, as auto-oxidation occurs extracellularly. We showed here, for the first time, that RA-differentiated SH-SY5Y cells can mimic, at least in part, an important mechanism of the 6-OHDA-induced cell death found in previous in vivo studies. Hence, the cellular model established by our research group presents essential neuronal features, being a suitable model for PD research. In Chapter II, RA-differentiated SH-SY5Y cells were used as cellular model to investigate disease molecular mechanisms, focusing upon cofilin-1. Our previous data have shown that oxidation of non-phosphorylate (activated) cofilin-1 leads to mitochondrial dysfunction and cell death induced by apoptosis in tumour cells. Here we found that cofilin-1 played a role in early stages of neuronal apoptosis induced by 6-OHDA in our cellular model since cofilin-1 mitochondrial translocation precedes organelle dysfunction. Overexpression of wild type CFL1 resulted in increased sensitivity of SH-SY5Y cells to 6-OHDA-induced neuronal cell death. Furthermore, overexpression of non-oxidizable CFL1 containing Cys-to-Ala mutations (positions 39, 80 and 139) increased neuronal resistance to this toxin, suggesting that oxidation is an important step in 6-OHDA toxicity. Follow-up experiments were performed in order to evaluate clinically whether cofilin-1 pathway proteins content is altered in PD post mortem human brain. Our findings showed a significant decrease in p-cofilin-1/cofilin-1 ratio in PD patients, which indicates an increase in the amount of activated cofilin-1 available for oxidation. Moreover, through principal component analysis, the immunodetection of cofilin-1 pathway proteins were able to discriminate controls and PD individuals during the early-stage of neuropathological changings. Hence, we demonstrated, for the first time, a possible role for cofilin-1 in PD pathogenesis and its potential use as biomarker. Taken together, our data showed that RA-differentiated SH-SY5Y cells present terminally-differentiated dopaminergic neuron features, that are essential to mimic dopaminergic neurons. By using this cellular model and post mortem brain tissue, we also demonstrated a possible role for cofilin-1 in early steps of the neurodegeneration process found in PD, which it could impact drug and biomarker discovery researches.

The dopaminergic neurodegeneration in the substantia nigra pars compacta (SNpc) is responsible for the marked motor impairment observed in Parkinson's disease (PD). However, the molecular mechanisms underlying this are not completely understood. Since by the time of diagnosis, 50-70% of the dopaminergic neurons of the nigrostriatal pathway have already been degenerated, it is difficult to investigate the early-stage events of disease pathogenesis. Due to inaccessibility of the human brain to study initial pathogenic mechanisms of the disease, experimental models have been developed in an attempt to elucidate PD etiology and its progression. Nevertheless, PD models are a controversial issue in neuroscience research since it is challenging to mimic human neuronal complexity. Therefore, the lack of optimal models that recreate disease pathology is one of the causes of failure of clinical trials that have attempted to find new/better PD therapies. Taking this in consideration, the development of more suitable models is necessary to improve our knowledge regarding PD etiological mechanisms. Additionally, the understanding of the advantages and disadvantages of models already established would also be beneficial for PD research, which our group addressed by reviewing this subject. Considering this, we chose SH-SY5Y cells as a PD model for our studies. To investigate the initial stages of PD-induced neurodegeneration, our work focused in the role of cofilin-1, a protein involved in mitochondrial dysfunction caused by oxidant-induced-apoptosis, which are two pathogenic processes strongly related to PD. Hence, in the thesis, we aimed to validate the use of retinoic-acid-(RA)-differentiated SH-SY5Y cells as an in vitro model and use it to investigate the potential role of cofilin-1 in the initial molecular and cellular mechanisms of PD. Although SH-SY5Y cells are widely used in PD research, their major drawback is their lack of important neuronal features, such as low levels of proliferation and stellate morphology. On the other hand, SH-SY5Y cells can acquire a neuronal phenotype when treated with differentiation agents such as RA. Since several protocols have been described, the consequence of which may be the discrepancies observed among studies regarding neuronal and dopaminergic features. In Chapter I, we aimed to validate a RA-differentiation protocol for SH-SY5Y cells previously established by our research group, focusing upon characterization of neuronal features and its subsequent response to 6-hydroxydopamine (6-OHDA), a toxin widely used to induce dopaminergic degeneration. RA-differentiated SH-SY5Y cells have low proliferative rates, a pronounced neuronal morphology and high expression of genes related to synapse vesicle cycle, dopamine synthesis/degradation, and dopamine transporter (DAT). After exploring phenotypic differences between these two models, we verified that RA-differentiated cells were more sensitive to 6-OHDA toxicity than undifferentiated cells, which could be related to an increase of DAT immunocontent. Many lines of evidence have showed that DAT is responsible for 6-OHDA uptake in vivo. Once inside the neuron, 6-OHDA underwent auto-oxidation causing a significant increase in oxidative stress. However, toxin uptake is not an essential step in undifferentiated SH-SY5Y cells, as auto-oxidation occurs extracellularly. We showed here, for the first time, that RA-differentiated SH-SY5Y cells can mimic, at least in part, an important mechanism of the 6-OHDA-induced cell death found in previous in vivo studies. Hence, the cellular model established by our research group presents essential neuronal features, being a suitable model for PD research. In Chapter II, RA-differentiated SH-SY5Y cells were used as cellular model to investigate disease molecular mechanisms, focusing upon cofilin-1. Our previous data have shown that oxidation of non-phosphorylate (activated) cofilin-1 leads to mitochondrial dysfunction and cell death induced by apoptosis in tumour cells. Here we found that cofilin-1 played a role in early stages of neuronal apoptosis induced by 6-OHDA in our cellular model since cofilin-1 mitochondrial translocation precedes organelle dysfunction. Overexpression of wild type CFL1 resulted in increased sensitivity of SH-SY5Y cells to 6-OHDA-induced neuronal cell death. Furthermore, overexpression of non-oxidizable CFL1 containing Cys-to-Ala mutations (positions 39, 80 and 139) increased neuronal resistance to this toxin, suggesting that oxidation is an important step in 6-OHDA toxicity. Follow-up experiments were performed in order to evaluate clinically whether cofilin-1 pathway proteins content is altered in PD post mortem human brain. Our findings showed a significant decrease in p-cofilin-1/cofilin-1 ratio in PD patients, which indicates an increase in the amount of activated cofilin-1 available for oxidation. Moreover, through principal component analysis, the immunodetection of cofilin-1 pathway proteins were able to discriminate controls and PD individuals during the early-stage of neuropathological changings. Hence, we demonstrated, for the first time, a possible role for cofilin-1 in PD pathogenesis and its potential use as biomarker. Taken together, our data showed that RA-differentiated SH-SY5Y cells present terminally-differentiated dopaminergic neuron features, that are essential to mimic dopaminergic neurons. By using this cellular model and post mortem brain tissue, we also demonstrated a possible role for cofilin-1 in early steps of the neurodegeneration process found in PD, which it could impact drug and biomarker discovery researches.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Parkinson’s disease (PD) is a neurodegenerative disease characterized by a progressive degeneration of dopaminergic neurons in the Substantia Nigra pars compact (SNpc) with consequent depletion of dopamine in the striatum, which gives rise to characteristic motor symptoms of PD. Although its etiology of is unknown, several studies have been suggested that oxidative stress and inflammation play a critical function in the physiopathology of PD and antioxidant and ani-inflammatory agents could be helpful to slown down the dopaminergic neurodegeneration. Thus, many studies have evaluated the potential neuroprotective effect of these agentes, including Carvacrol (CA). CA is a phenolic monoterpene found in essential oils of many aromatic plants and it has a variety of pharmacological effects on Central Nervous System, including antioxidant and anti-inflammatory activities. In this context, the objective of this study was to investigate a possible neuroprotective effect of CA in two rat models of PD. Two experiments were performed: in the experiment I, male Wistar rats were submitted to repeated administration of a low dose (0.1 mg/kg, s.c.) of reserpine (RES) or vehicle of reserpine (VR) and concomitantly treated with CA at doses of 12.5 or 25 mg/kg (i.p.) or vehicle of carvacrol (VC). Across the treatment, the animal motor behavior was evaluated by catalepsy test, open field test and assessment of oral movements. In the experiment II, male Long-Evans rats were pretreated for seven days with CA at doses of 50 or 100 mg/kg (i.p.) or VC, and were then submitted to unilateral injection of 6-hydroxydopamine (6-OHDA) or vehicle of 6-OHDA into the medial forebrain bundle (MFB). The animals were treated with CA or VC for three weeks after injection. Thereafter, they were assessed for motor behavioral function by open field, cylinder test, rotarod and amphetamine-induced circling test. In both experiments, upon completion behavioral tests, rats were perfused and theirs brains were subjected for tyrosine hydroxylase (TH) immunohistochemical analysis. In the experiment I, the results showed that the CA treatment, in both doses 12.5 e 25 mg/kg, was able to prevent the catalepsy behavior and the development of vacuous chewing movements induced by RES, however, CA failed to revert the decreased locomotor activity induced by RES in the open field test. In addition, CA in both doses prevented the depletion of TH immunostaining induced by RES in the SNpc and dorsal striatum. In the experiment II, the treatment with CA at dose of 50 mg/kg prevented the motor deficits induced by 6-OHDA injection in the open field test, cylinder test and rotarod, and increased the number of rotations induced by amphetamine. Moreover, CA attenuated the dopaminergic neurons damage in the SNpc and dorsal striatum induced by 6-OHDA injection. Taken together, our results suggest that CA shows neuroprotective effect, preventing or attenuating motor and neurochemical impairments induced by RES and 6-OHDA, so it may be regarded a promising therapeutic candidate for the prevention or treatment of PD. / A Doença de Parkinson (DP) é uma doença neurodegenerativa caracterizada por uma degeneração progressiva de neurônios dopaminérgicos da Substância Negra parte compacta (SNpc), o que resulta nas alterações motoras características desta patologia. Embora sua etiologia ainda permaneça desconhecida, vários estudos indicam que o estresse oxidativo e a inflamação exercem uma função crítica na fisiopatologia da DP e agentes antioxidantes e anti-inflamatórios poderiam desacelerar a neurodegeneração dopaminérgica. Assim, tem sido crescente o número de pesquisas relacionadas a investigação do potencial neuroprotetor destes agentes, entre eles, o Carvacrol (CA). O CA é um monoterpeno fenólico encontrado nos óleos essenciais de diversas plantas aromáticas e apresenta uma variedade de atividades farmacológicas sobre o Sistema Nervoso Central, incluindo atividades antioxidante e anti-inflamatória. Neste contexto, o objetivo deste estudo foi investigar um possível efeito neuroprotetor do CA em ratos submetidos a dois modelos de DP. Foram realizados dois experimentos: no experimento I, ratos Wistar foram submetidos a administração repetida de uma dose baixa (0,1 mg/kg, s.c.) de reserpina (RES) ou veículo da reserpina (VR) e tratados concomitantemente com CA nas doses de 12,5 ou 25 mg/kg (i.p.) ou com o veículo do carvacrol (VC). Ao longo do experimento, os animais tiveram seu comportamento motor avaliado através dos testes de catalepsia, campo aberto e avaliação dos movimentos orais. No experimento II, ratos Long-Evans foram pré-tratados por sete dias com CA nas doses de 50 ou 100 mg/kg (i.p.) ou VC, e então foram submetidos a uma injeção unilateral de 6-hidroxidopamina (6-OHDA) ou veículo no feixe prosencefálico medial (medial forebrain bundle -MFB). Os animais foram tratados com CA ou VC por três semanas após a injeção de 6-OHDA e após este período tiveram seu comportamento motor avaliado através dos testes do campo aberto, cilindro, rotarod e rotações induzidas por anfetamina. Em ambos os experimentos, ao fim dos testes comportamentais, os animais foram perfundidos e seus cérebros foram processados para imunohistoquímica para tirosina hidroxilase (TH). No experimento I, os resultados mostraram que o CA em ambas as doses (12,5 e 25 mg/kg) preveniu o comportamento de catalepsia e o desenvolvimento de movimentos de mastigação no vácuo induzidos pela RES, porém não reverteu a redução da atividade locomotora causada pela RES no teste do campo aberto. O CA em ambas as doses preveniu a redução da marcação de TH induzida pela RES na SNpc e no estriado dorsal. No experimento II, os resultados mostraram que o CA na dose de 50 mg/kg preveniu os déficits motores induzidos pela injeção de 6-OHDA nos testes do campo aberto, cilindro e rotarod, e aumentou o número de rotações induzidas por anfetamina. Além disso, o CA atenuou o dano provocado pela injeção de 6-OHDA nos neurônios dopaminérgicos da SNpc e estriado dorsal. Os resultados obtidos no presente estudo sugerem que o CA apresenta um efeito neuroprotetor, prevenindo ou atenuando as alterações motoras e neuroquímicas induzidas pela RES e 6-OHDA. Desta forma, o CA pode ser considerado um candidato terapêutico promissor para a prevenção ou tratamento da DP.

The aim of this study was to investigate whether exercise could improve motor behavioral deficits and alter expression of glial fibrillary acidic protein (GFAP) in dorsal striatum in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson’s disease (PD). To this end, animals were randomly divided into 4 groups: sham sedentary (SS, n = 7); sham trained (ST, n=8); lesioned sedentary (LS, n=8) and lesioned trained (LT, n = 8). Rats were unilaterally lesioned with 6-OHDA (10 μg/3 μg) injected into the left medial forebrain bundle and sham groups were only injected with vehicle solution. The treadmill training protocol consisted of running with progressive increase in velocity, 5 days/week, during 4 weeks. Behavioral tasks were applied to asses the motor abilities of all animals prior to 6-OHDA injection and at 8th and 29th days post-injection. The tyrosine hydroxylase (TH - in substantia nigra pars compacta) and GFAP (in dorsal striatum) immunostaining was evaluated by semiquantitative analysis of the intensity (optical density - OD). The 6-OHDA lesion decreased the OD of TH and increased the OD of GFAP. In addition, the 6-OHDA lesion increased the number of ipsilateral rotations induced by methylphenidate (40 mg/kg, i.p., 30 min) and caused motor behavioral deficits. On the other hand, the treadmill training resulted in an increase in maximal exercise capacity in both trained groups (ST and LT). The training was able to reduce the number of ipsilateral rotations and ameliorated the motor behavioral deficits on 8th and 29th days postlesion. Interestingly, the exercise led to a significant increase in OD of GFAP in the LT group while there was no such effect in ST group. Our results indicate that treadmill training can improve motor behavioral deficits and suggest that the effects of exercise may be directly or, indirectly, mediated by astrocytes, as an increase in GFAP was observed in the dorsal striatum. Nevertheless, these are the first data showing an increase in GFAP expression post-exercise in this model and further research is needed to determine the precise action of exercise on astrocytes in Parkinson’s disease.

The aim of this study was to investigate whether exercise could improve motor behavioral deficits and alter expression of glial fibrillary acidic protein (GFAP) in dorsal striatum in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson’s disease (PD). To this end, animals were randomly divided into 4 groups: sham sedentary (SS, n = 7); sham trained (ST, n=8); lesioned sedentary (LS, n=8) and lesioned trained (LT, n = 8). Rats were unilaterally lesioned with 6-OHDA (10 μg/3 μg) injected into the left medial forebrain bundle and sham groups were only injected with vehicle solution. The treadmill training protocol consisted of running with progressive increase in velocity, 5 days/week, during 4 weeks. Behavioral tasks were applied to asses the motor abilities of all animals prior to 6-OHDA injection and at 8th and 29th days post-injection. The tyrosine hydroxylase (TH - in substantia nigra pars compacta) and GFAP (in dorsal striatum) immunostaining was evaluated by semiquantitative analysis of the intensity (optical density - OD). The 6-OHDA lesion decreased the OD of TH and increased the OD of GFAP. In addition, the 6-OHDA lesion increased the number of ipsilateral rotations induced by methylphenidate (40 mg/kg, i.p., 30 min) and caused motor behavioral deficits. On the other hand, the treadmill training resulted in an increase in maximal exercise capacity in both trained groups (ST and LT). The training was able to reduce the number of ipsilateral rotations and ameliorated the motor behavioral deficits on 8th and 29th days postlesion. Interestingly, the exercise led to a significant increase in OD of GFAP in the LT group while there was no such effect in ST group. Our results indicate that treadmill training can improve motor behavioral deficits and suggest that the effects of exercise may be directly or, indirectly, mediated by astrocytes, as an increase in GFAP was observed in the dorsal striatum. Nevertheless, these are the first data showing an increase in GFAP expression post-exercise in this model and further research is needed to determine the precise action of exercise on astrocytes in Parkinson’s disease.

The aim of this study was to investigate whether exercise could improve motor behavioral deficits and alter expression of glial fibrillary acidic protein (GFAP) in dorsal striatum in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson’s disease (PD). To this end, animals were randomly divided into 4 groups: sham sedentary (SS, n = 7); sham trained (ST, n=8); lesioned sedentary (LS, n=8) and lesioned trained (LT, n = 8). Rats were unilaterally lesioned with 6-OHDA (10 μg/3 μg) injected into the left medial forebrain bundle and sham groups were only injected with vehicle solution. The treadmill training protocol consisted of running with progressive increase in velocity, 5 days/week, during 4 weeks. Behavioral tasks were applied to asses the motor abilities of all animals prior to 6-OHDA injection and at 8th and 29th days post-injection. The tyrosine hydroxylase (TH - in substantia nigra pars compacta) and GFAP (in dorsal striatum) immunostaining was evaluated by semiquantitative analysis of the intensity (optical density - OD). The 6-OHDA lesion decreased the OD of TH and increased the OD of GFAP. In addition, the 6-OHDA lesion increased the number of ipsilateral rotations induced by methylphenidate (40 mg/kg, i.p., 30 min) and caused motor behavioral deficits. On the other hand, the treadmill training resulted in an increase in maximal exercise capacity in both trained groups (ST and LT). The training was able to reduce the number of ipsilateral rotations and ameliorated the motor behavioral deficits on 8th and 29th days postlesion. Interestingly, the exercise led to a significant increase in OD of GFAP in the LT group while there was no such effect in ST group. Our results indicate that treadmill training can improve motor behavioral deficits and suggest that the effects of exercise may be directly or, indirectly, mediated by astrocytes, as an increase in GFAP was observed in the dorsal striatum. Nevertheless, these are the first data showing an increase in GFAP expression post-exercise in this model and further research is needed to determine the precise action of exercise on astrocytes in Parkinson’s disease.