Alzheimer’s disease (AD) is a neurodegenerative disorder, with extensive evidence implicating the misfolding, aggregation and deposition of the amyloid-β (Aβ) peptide as central to the pathogenesis. Heparan sulfate (HS) is an interactive glycosaminoglycan, attached to core proteins as HS proteoglycans (HSPGs). HSPGs are present on cell surfaces and in the extracellular matrix where they facilitate multiple signaling functions, but HS is also consistently present in all amyloid deposits, including those of AD. In amyloidosis HS has been studied as an aggregation template, promoting fibril formation and serving a scaffold function in the resulting deposits. The objective of this thesis was to assess how cell surface HS is potentially implicated in Aβ amyloidosis and the associated neuroinflammation of AD.   In AD brain we determined that HS predominantly accumulated in Aβ deposits with dense cores and found glial-expressed HSPGs within these deposits. Aβ elevated HSPG levels in primary glial cultures, implicating activated glia as one source of the Aβ-associated HS. Next, we determined that microglial HSPGs are critical for the upregulation of interleukin-1β and tumor necrosis factor-α following exposure to lipopolysaccharide, an established inflammatory insult. Together these results raise the possibility that Aβ-induced expression of microglial HSPGs may promote neuroinflammation.   Multiple mechanisms of Aβ toxicity have been proposed and different Aβ assemblies exert their toxicity through alternative routes. We found that three different preparations of Aβ aggregates all exhibited HS-dependent cytotoxicity, which in part correlated with Aβ internalization. Furthermore, heparin treatment attenuated Aβ cytotoxicity and uptake. In Aβ-positive AD microvasculature, HS deposited with Apolipoprotein E (ApoE) and its receptor, the low density lipoprotein receptor-related protein 1 (LRP1). In cell culture, HS and LRP1 co-operated in Aβ interactions and the addition of ApoE increased the levels of cell-associated Aβ in a HS- and LRP1-dependent manner. This ApoE-mediated increase in cell-associated Aβ may promote toxicity and vascular degeneration, but equally HS-mediated internalization of Aβ could represent a clearance route across the blood-brain-barrier. The findings presented here illustrate multiple roles for cell-surface HSPGs in interactions relevant to the pathogenesis of AD.

Lipids are important for the structural and physiological functions of neuronal cell membranes. Alterations in their lipid composition may result in membrane dysfunction and subsequent neuronal deficits that characterise various disorders. This study focused on profiling lipids of aged and LPS-treated rat brain and liver tissue with a view to explore the effect of atorvastatin in neuroinflammation, and examining lipid changes in different areas of rat brain of the Flinders Sensitive Line (FSL) rats, a genetic model of depression. Lipids and other analytes extracted from tissue samples were analysed with proton nuclear magnetic resonance spectroscopy (1H-NMR), gas chromatography (GC) and liquid chromatography-tandem mass spectroscopy (LC/ESI-MS/MS). Changes in the lipid profiles suggested that brain and liver responded differently to ageing and LPS-induced neuroinflammation. In the aged animals, n-3 PUFA were reduced in the brain but were increased in the liver. However, following treatment with LPS, these effects were not observed. Nevertheless, in both models, brain concentration of monounsaturated fatty acids was increased while the liver was able to maintain its monounsaturated fatty acid concentration. Atorvastatin reversed the reduction in n-3 PUFA in the aged brain without reducing brain and liver concentration of cholesterol. These findings further highlight alterations in lipid metabolism in agerelated neuroinflammation and show that the anti-inflammatory actions of atorvastatin may include a modulation of fatty acid metabolism. When studying the FSL model, there were differences in the lipid profile of different brain areas of FSL rats compared to Sprague-Dawley controls. In all brain areas, arachidonic acid was increased in the FSL rats. Docosahexaenoic acid and ether lipids were reduced, while cholesterol and sphingolipids were increased in the hypothalamus of the FSL rats. Furthermore, total diacylglycerophospholipids were reduced in the prefrontal cortex and hypothalamus of the FSL rats. These results show differences in the lipid metabolism of the FSL rat brain and may be suggestive of changes occurring in the brain tissue in depression.

Chronic ethanol exposure results in neuroadaptations that drive the progression of an alcohol use disorder (AUD). One such driving force is alcohol-induced neurodegeneration. Neuroinflammation has been proposed as a mechanism underlying this damage. Although neuroinflammation is a physiological response to damage, overactivation of its pathways can lead to neurodegeneration. A hallmark indicator of neuroinflammation is microglial activation, but microglial activation is a heterogeneous continuum of phenotypes that can promote or inhibit neuroinflammation. Furthermore acute microglial activation is necessary to restore homeostasis, but prolonged activation can exacerbate damage. The diversity of microglia makes both the level and timecourse of activation vital to understanding their role in damage and/or recovery. The current set of experiments examines the effects of ethanol on microglia within the hippocampus and entorhinal cortex in a binge model of alcohol-induced neurodegeneration. In the first set of experiments, the phenotype of microglia activation was assessed using Raivich’s 5-stages of activation that separates pro- and anti-inflammatory forms of microglia. Morphological and functional assessments suggest that ethanol does not elicit classical microglial activation but instead induces partially activated microglia. In the second set of experiments, the earliest signs of microglial activation were determined to understand the initiation of microglial activation. Experiments indicated that activation occurred subsequent to previous evidence of neuronal damage; however, activation was accompanied by a loss of microglia and the discovery of dystrophic microglia. The final set of experiments examined whether alcohol-induced partial activation of microglia would show a differential response with further alcohol exposure. Experiments showed that animals previously exposed to ethanol showed a greater response to a second ethanol insult. Overall, these studies suggest that although alcohol may initially interrupt the normal microglia response, during abstinence from ethanol a partial activation phenotype appears that may contribute to recovery. Once activated, however, data suggest that these microglia are primed and upon subsequent exposure show an increased response. This heterogeneous microglial response with respect to time does not necessarily reflect a neuroinflammatory response that would be neurodegenerative but does imply that chronic ethanol consumption affects the normal neuroimmune system.

<p>Neuroinflammation associated with lumbar radiculopathy and peripheral nerve injury is characterized by locally increased levels of the pro-inflammatory cytokine tumor necrosis factor alpha (TNF&alpha;). Systemic administration of TNF antagonists for radiculopathy in the clinic has shown mixed results, and there is growing interest in local delivery of anti-inflammatory drugs to treat this pathology, as well as similar inflammatory events of peripheral nerve injury. Curcumin, a known antagonist of TNF&alpha; in multiple cell types and tissues, was chemically modified and conjugated to a thermally responsive elastin-like polypeptide (ELP) to create an injectable depot for sustained, local delivery of curcumin to treat neuroinflammation. </p><p>ELPs are biopolymers capable of thermally-triggered in situ depot formation and have been successfully employed as drug carriers and biomaterials in several applications. A library of ELP-curcumin conjugates were synthesized and characterized. One lead conjugate was shown to display high drug loading, rapidly release curcumin in vitro via degradable carbamate bonds, and retain in vitro bioactivity against TNF&alpha; and NF-&kappa;B with near-equivalent potency compared to free curcumin. When injected into the perineural space via intramuscular (i.m.) injection proximal to the sciatic nerve in mice, ELP-curcumin conjugates underwent a thermally triggered soluble-insoluble phase transition, leading to in situ formation of a depot that released curcumin over 4 days post-injection and decreased systemic exposure of curcumin 3-fold. </p><p>The results of this dissertation support the use of ELP as a drug carrier for local perineural drug delivery, and the strategy presented here for drug conjugate development and use of depot-forming ELP-curcumin conjugates represents a novel means of providing sustained treatment of neuroinflammation and pain associated with radiculopathy and peripheral nerve injury.</p> / Dissertation

Cannabinoids have been shown to modulate the immune system in vitro and in animal models. A major area of interest is how cannabinoids impact the brain. A whole variety of neuropathies or brain disorders, such as AIDS dementia, Parkinson’s disease, Multiple Sclerosis and Alzheimer’s disease, are associated with a hyperinflammatory response within the brain. Microglia, the resident macrophages of the brain, are the major cell type responsible for the persistent elicitation of pro-inflammatory cytokines (IL-1a, IL-1b, IL-6, TNFa) and other mediators. In vitro experiments have demonstrated that the partial exogenous cannabinoid agonist delta-9-tetrahydrocannabinol (D9-THC) and the potent synthetic exogenous cannabinoid agonist CP55940 down-regulate the robust production of pro-inflammatory cytokines elicited in response to bacterial lipopolysaccharide (LPS) at the mRNA level. These observations suggest that cannabinoids, devoid of psychotropic properties, have the potential to betherapeutic agents. These highly lipophilic compounds can pass through the blood brain barrier and act through specific cannabinoid receptors, cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2). CB1 and CB2 are expressed in the brain and the periphery, respectively, and may serve as molecular targets for ablating chronic brain inflammation. Electrophoretic mobility shift assays (EMSA) were used to assess the effects of D9-THC and CP55940 on the LPS-induced binding interactions of the universal transcription factor NFkB to its cognate promoter binding site in BV-2 microglial-like cells. EMSA analyses demonstrated that the D9-THC and CP55940 down-regulated LPS-induced NFkB binding in BV-2 cells in a biphasic manner. Furthermore, reporter activity assays determined that D9-THC and CP55940 attenuated LPS-induced, NFkB transcriptional activity in the same biphasic manner. We then determined the specificity in which cannabinoids inhibit NFkB function. Real-Time RT-PCR analysis demonstrated that BV-2 cells did not express CB1 mRNA, but they do express CB2 mRNA when untreated and stimulated with IFN-g or LPS. We performed specificity studies using CB1 and CB2 selective agonists and antagonists with our reporter activity assays. The CB1-selective agonist ACEA did not affect NFkB transcriptional activity but the CB2-selective agonist O-2137 exerted a significant decrease in activity. Furthermore, the CB1 antagonist SR141716A could not reverse the inhibitory effects of CP55490 but those effects were blocked by the CB2 antagonist SR144528. Lastly, we determined the site of action in which cannabinoids inhibit NFkB function by assessing the effects of D9-THC and CP55940 on NFkB’s inhibitor protein IkBa. IkBa retains NFkB in the cytoplasm until stimulus-induced cell activation. Neither cannabinoid compound was able to inhibit the phosphorylation of IkBa, which initiates its degradation. However both cannabinoids inhibited the complete degradation of IkBa. Western immunoblot analysis also demonstrated that comparable levels of endogenous and phosphorylated p65, the transactivation subunit of the NFkB protein (p65/p50), were detected in the nucleus of LPS-stimulated BV-2 cells pre-treated with or without D9-THC. These results suggest that, in addition to inhibiting the proteolytic degradation of IkBa, there is also a mechanism of action in the nucleus that prevents the proper binding and subsequent transcriptional activity of NFkB. Collectively, these results suggest that cannabinoids suppress pro-inflammatory cytokine gene expression at the transcriptional level, but it is likely that there is more than one signal transduction pathway involved in the cannabinoid-mediated inhibition of NFkB function.

A glândula pineal é responsável pela produção circadiana do hormônio melatonina, o qual possui além da propriedade cronobiótica, ações relacionadas à neurogênese e atividade anti-inflamatória. A prevalência do distúrbio do metabolismo dos carboidratos conhecido como diabetes mellitus afeta cada vez mais a população mundial em decorrência do aumento da expectativa de vida, alimentação inadequada, obesidade e detrimento de atividade física regular, caracterizando além dos sintomas clássicos como hiperglicemia, polifagia, polidipsia e glicosúria, problemas relacionados a plasticidade cerebral, neuroinflamação e maior probabilidade do desenvolvimento de doenças neurodegenerativas. A hiperglicemia crônica influencia negativamente a síntese e secreção de melatonina, fato que contribui ainda mais para o agravamento dos sintomas do quadro de diabetes, formando um ciclo de retroalimentação positiva. Tendo em vista as recentes pesquisas que mostram que a molécula de melatonina atua como agente anti-inflamatório, neuroprotetor e indutor da neurogênese, nos propomos a investigar, com este trabalho, se a suplementação via oral de melatonina em ratos modelo de diabetes tipo 2 (Goto-Kakizaki) é capaz de amenizar os danos cerebrais provocados pela hiperglicemia crônica. Nossos resultados demonstram que a suplementação com melatonina não foi capaz de alterar a glicemia de jejum dos animais, tampouco torná-los mais sensíveis à insulina mediante teste de tolerância à glicose. Entretanto, a mesma atuou sobre o peso corporal dos animais diabéticos, fato ainda a ser elucidado do ponto de vista molecular. As diferenças encontradas no que se refere a expressão gênica e proteica de fatores estudados, se dão principalmente pelo fato do animal ser hiperglicêmico (Goto-Kakizaki) ou não (Controle), sendo que a melatonina é capaz de atuar em questões pontuais. Ainda, os animais Goto-Kakizaki não apresentam processos inflamatórios no hipocampo e hipotálamo. / The pineal gland is responsible for the circadian production of the hormone melatonin, which has besides chronobiotic properties, actions related to adultneurogenesis and anti-inflammatory activityThe prevalence of carbohydrate metabolism disorder known as diabetes mellitus increasingly affects the world population due to increased life expectancy, inadequate diet, obesity, and the detriment of regular physical activity, characterized in addition to classic symptoms such as hyperglycemia, polyphagia, polydipsia,and glycosuria. This problem related to brain plasticity, neuroinflammation, and increased probability of developing neurodegenerative diseases. Chronic hyperglycemia negatively influences the synthesis and secretion of melatonin, a fact that contributes to the worsening symptoms of diabetes, forming a positive feedback loop. Taking in count the recent studies showing that the melatonin molecule acts as an anti-inflammatory, neuroprotective and neurogenetic inducer, we propose to investigate whether oral supplementation of melatonin in type 2 diabetes mellitus (Goto-Kakizaki) can alleviate the brain damage induced by chronic hyperglycemia. Our results demonstrate that supplementation with melatonin was not able to alter the fasting glycemia of the animals, nor did it make them more sensitive to insulin through a glucose tolerance test. However, it acted on the body weight of diabetic animals, a fact still to be elucidated from the molecular point of view. The differences found in gene expression and protein expression of the studied factors are mainly because the animal is hyperglycemic (Goto-Kakizaki) or not (Control), and melatonin can act on specific questions. Furthermore, Goto-Kakizaki animals do not present an inflammatory processin the hippocampus and hypothalamus.

La dépression est un trouble neurologique grave et la deuxième cause d’invalidité dans le monde. Récemment, la signalisation du récepteur X aux rétinoïdes et l’inflammation chronique ont été identifiées comme facteurs génétiques et environnementaux. Au cours de ma thèse, j'ai étudié la façon dont le récepteur X gamma aux rétinoïdes (RXRg) contrôle la neuroinflammation dans deux modèles précliniques de dépression. J'ai montré que RXRg contrôle un signal spécifique lié à l'âge, entrainant la sénescence et l'hypoactivité des cellules microgliales. Ce signal impacte également la phagocytose microgliale et contribue à l'hypertrophie neuronale dans le striatum, elle-même associée à des symptômes dépressifs. De plus, j'ai pu mettre en évidence une activité antidépressive des rexinoïdes et des fibrates dans le stress de défaite sociale chronique, ainsi que leur mécanisme cellulaire. Les données obtenues pourraient permettre le développement de nouveaux traitements antidépresseurs. / Depression is severe mental disorder that is a second leading contributor to diseases burden. Recently, retinoid X receptor signaling and chronic inflammation have been identified as genetic and environmental factors. However, a cross-talk between these two factors was poorly understood. During my PhD I have studied how retinoid X receptor gamma (RXRg) controls neuroinflammation in two pre-clinical models of depression. I have shown that RXRg controls age-specific signal that drives microglial senescence and hypoactivity. The latter, impacts also microglial phagocytosis and contribute to neuronal hypertrophy in the striatum that previously was associated with depressive symptoms. Additionally, I showed antidepressant activity and cellular mechanism of rexinoids and fibrates in chronic social defeat stress. Obtained data have strong therapeutic potential that may allow for development of new antidepressant therapies.

A Doença de Alzheimer (DA) tem sido relacionada com danos oxidativos. O objetivo desse trabalho foi investigar o envolvimento NADPH oxidase 2 (Nox2), uma enzima que produz espécies reativas de oxigênio, na memória, na expressão de proteínas relacionadas à DA, na inflamação e morte neuronal no hipocampo na patologia Alzheimer-símile induzida por estreptozotocina (STZ), comparando os efeitos dessa droga em camundongos nocautes para Nox2 e camundongos selvagens (WT). A expressão gênica de Nox2 foi aumentada em animais WT após a injeção de STZ, além disso, esses animais apresentaram déficit de memória, aumento na fosforilação de TAU, na expressão de beta-amilóide, neurofilamentos, caspase-3 e marcadores de astrócitos e microglia, além de aumento na liberação de citocinas inflamatórias, após o tratamento. Estes efeitos não foram observados após a deleção de Nox2. A deleção de Nox2 aumentou a produção basal de IL-10, sugerindo que este pode ser um mecanismo pelo qual os camundongos nocautes são protegidos contra a patologia Alzheimer-símile induzida por STZ. / Alzheimer\'s disease (AD) has been linked to oxidative stress. The goal of this study was to investigate the involvement of NADPH oxidase 2 (nox2), an enzyme that produces reactive oxygen species, in memory, in AD-related proteins expression, inflammation and neuronal death in the hippocampus in the streptozotocin (STZ)-induced AD-like pathology by comparing the effects of that drug on mice lacking Nox2 and wild type (Wt) mice. Nox2 gene expression was increased in Wt mice after STZ injection. Moreover, these animals presented impairment in memory, increased phosphorylation of Tau and increased amyloid-&#946; protein, neurofilaments, caspase-3 and astrocyte and microglial markers expression, in addition to increased inflammatory cytokines release after treatment. Nox2 depletion prevented these effects. The baseline IL-10 levels were found increased following Nox2 deletion, suggesting that this is one mechanism by which mice lacking Nox2 are protected against STZ-induced AD-like pathology.

O presente trabalho compreende o estudo da resposta imune e inflamatória no sistema nervoso central (SNC) de camundongos ou ratos-veadeiros (Peromyscus maniculatus) frente a infecção por dois diferentes tipos de vírus neurotrópicos, o vírus da estomatite vesicular (VEV) e o herpesvírus bovino tipo 5 (BoHV-5). Na primeira etapa, foi avaliada a função das células residentes do SNC no tocante à expressão de quimiocinas durante a infecção pelo VEV em ratos-veadeiros. No presente estudo, durante a encefalite causada pelo vírus da estomatite vesicular sorotipo New Jersey (VEVNJ) em ratos-veadeiros, as quimiocinas RANTES e MCP-1 foram expressas somente no bulbo olfatório (BO), local onde o vírus estava restrito. A expressão de quimiocinas foi seguida de um influxo de células inflamatórias no BO tardiamente no curso da doença aguda. A quimiocina RANTES foi expressa por neurônios, astrócitos e micróglia, ao passo que MCP-1 foi expressa por neurônios e astrócitos. Embora os astrócitos e a micróglia tenham respondido à infecção pelo VEVNJ ao expressarem quimiocinas, os neurônios foram o principal tipo celular infectado pelo vírus. Portanto, os neurônios infectados podem exercer um papel crucial na geração da resposta imune no BO. A sinalização entre neurônios e outras células residentes do SNC muito provavelmente é o mecanismo pelo qual os astrócitos e micróglia são ativados durante a encefalite causada pelo VEVNJ. Os resultados aqui apresentados, também indicam que a expressão de RANTES e MCP-1 no BO de ratos-veadeiros infectados pelo VEVNJ pode ajudar a prevenir a disseminação do vírus para outras áreas do SNC. Na segunda etapa, foi avaliada a susceptibilidade de camundongos isogênicos BALB/c frente à infecção pelo BoHV-5 em camundongos isogênicos BALB/c em diferentes dias pós-inoculação (DPI). O BoHV-5 quando inoculado pela via intracraniana foi capaz de infectar e se replicar no SNC de camundongos BALB/c. Entretanto, até o momento avaliado (15 DPI), os animais sobreviveram a infecção sem apresentar sinais neurológicos evidentes. A infecção foi acompanhada de uma resposta imune do tipo Th1 importante, com expressão significativa das citocinas IFN-Y e TNF-&#945;, e quimiocina CCL-2. A expressão das citocinas e quimiocinas se deu principalmente no início da infecção (3 e 4 DPI), a qual foi seguida por uma meningo-encefalite com manguitos perivasculares e periventriculite, compostas predominantemente por macrófagos e linfócitos. Após a expressão significativa das citocinas e quimiocina, os animais foram capazes de debelar a infecção aguda, uma vez que partículas virais viáveis não foram detectadas após o 6 DPI. Entretanto, o BoHV-5 foi capaz de infectar o gânglio trigeminal, uma vez que grande quantidade de DNA de BoHV-5 foi detectada no 3 DPI, o que foi confirmado pela presença de antígenos virais no citoplasma de neurônios do gânglio trigeminal de camundongos BALB/c infectados / The present work comprises the study of immune and inflammatory responses in the central nervous system (CNS) of mice or deer mice (Peromyscus maniculatus) during infection by two different neurotropic viruses, the vesicular stomatitis virus (VSV) and bovine herpesvirus type 5 (BoHV-5). In the first part, the role of CNS resident cells regarding chemokine expression in deer mice infected with VSV was evaluated. Here, we demonstrated that during vesicular stomatitis New Jersey virus (VSNJV) encephalitis in deer mice, chemokines RANTES and MCP-1 are expressed only in the olfactory bulb (OB), where the virus was restricted. This chemokine expression was followed by the influx of inflammatory cells to the OB later in the course of acute disease. Neurons, astrocytes and microglia expressed RANTES, whereas MCP-1 was expressed by neurons and astrocytes. Although astrocytes and microglia responded to VSNJV infection by expressing chemokines, neurons were the predominantly infected cell type. Therefore, infected neurons may have a critical role in initiating an immune response in the OB. The signaling between neurons and other CNS resident cells is most likely the mechanism by which astrocytes and microglia are activated during the course of VSV encephalitis. Our results also indicate that the expression of RANTES and MCP-1 in the OB of deer mice infected with VSNJV might help prevent the spread of VSNJV to other areas of CNS. In the second part of the study, the susceptibility of isogenic BALB/c mice to BoHV-5 infection was evaluated in different days post-inoculation (DPI). BoHV-5, when inoculated through intracranial route, was able to infect and replicate within the CNS of BALB/c mice. However, until the evaluated time (15 DPI), the mice was able to survive without showing prominent neurological signs. The infection was accompanied by an important Th1 immune response, with a significant expression of the cytokines IFN-Y and TNF-&#945;, and chemokine CCL-2. The expression of these cytokines and chemokines was detected mainly on the early course of infection (3 and 4 DPI), and was followed by a meningoencephalitis with perivascular cuffing and periventriculitis, composed mainly by macrophages and lymphocytes. After the expression of cytokines and chemokine, the mice were able to curb BoHV-5 acute infection, since viable viral particles were not detected after 6 DPI. However, BoHV-5 was able to infect the trigeminal ganglia, since a large number of BoHV-5 DNA copies was detected on 3 DPI, which was confirmed by the presence of viral antigens within the cytoplasm of neurons in the trigeminal ganglia of infected BALB/c mice

A neurodegeneração é o resultado da destruição progressiva e irreversível dos neurônios no sistema nervoso central, apresentando causas desconhecidas e mecanismos patológicos não totalmente elucidados. Fatores como a idade, o aumento da formação de radicais livres e/ou estresse oxidativo, defeito no metabolismo energético, a inflamação e acúmulo de elementos neurotóxicos e de proteínas malformadas no lúmen do retículo endoplasmático (RE) contribuem para o desenvolvimento dos processos neurodegenerativos. O sistema canabinoide tem sido proposto como neuroprotetor em diversos modelos de neurodegeneração como hipóxia aguda e epilepsia, isquemia cerebral, lesão cerebral e modelos de estresse oxidativo. Assim, este trabalho teve como objetivo investigar o papel do sistema canabinoide em uma linhagem de neuroblastoma (Neuro 2a) submetida a condições de estresse oxidativo (H2O2), inflamação (LPS) e estresse do RE (tunicamicina), avaliando parâmetros de viabilidade celular e vias de sinalização envolvidas. Nossos resultados mostram que o agonista canabinoide ACEA foi capaz de proteger as células da morte celular causada pela inflamação e pelo estresse de retículo endoplasmático, mas não pelo estresse oxidativo. Esse efeito neuroprotetor exercido pelo ACEA parece pelo menos em parte ocorrer via receptor CB1 no modelo de inflamação e ser independente deste receptor no modelo de estresse de RE. Os efeitos neuroprotetores observados envolveram a modulação dos níveis de proteínas pré-apoptóticas, CHOP e Caspase 12, e da proteína relacionada à sobrevivência celular ERK 1/2. Nossos dados sugerem um papel neuroprotetor do sistema canabinoide em mecanismos relacionados aos processos neurodegenerativos e propõem a manipulação desse sistema como possível alvo terapêutico. / Neurodegeneration is the result of progressive and irreversible destruction of neurons in the central nervous system, with unknown causes and pathological mechanisms not fully elucidated. Factors such as age, increased formation of free radicals and/or oxidative stress, defects in energetic metabolism, inflammation and accumulation of neurotoxic factors and misfolded proteins in the lumen of the endoplasmic reticulum (ER) contribute to the development of neurodegenerative processes. The cannabinoid system has been proposed as neuroprotector in several models of neurodegeneration such as acute hypoxia and epilepsy, cerebral ischaemia, brain injury and oxidative stress models. This work aimed to investigate the role of the cannabinoid system in a neuroblastoma line (Neuro 2a) submitted to oxidative stress (H2O2), inflammation (LPS) and ER stress (tunicamycin) conditions, assessing cell viability parameters and signaling pathways involved. Our results show that the ACEA cannabinoid agonist was able to protect cells from cell death caused by inflammation and ER stress, but not from oxidative stress. This neuroprotective effect exerted by ACEA appears to occur at least in part via the CB1 receptor in inflammation model and it seems to be independent of this receptor in the ER stress model. The neuroprotective effects observed involved the modulation of the levels of pre-apoptotic proteins CHOP and Caspase 12 and the cell survival related protein ERK 1/2. Our data suggest a neuroprotective role of the cannabinoid system in mechanisms related to neurodegenerative processes and propose it as possible therapeutic target.