A hidrocefalia é um desequilíbrio no fluxo ou absorção do líquido cefalorraquidiano, resultando em uma dilatação no sistema ventricular. O tratamento da hidrocefalia usualmente utilizado é cirúrgico (shunt), mas nem todos os pacientes podem ser submetidos ao tratamento cirúrgico imediatamente após o diagnóstico. Com isso, medidas neuroprotetoras vêm sendo testadas a fim de minimizar as lesões teciduais envolvidas. A Memantina é antagonista não competitivo do receptor N-metil-D-aspartato (NMDA), que revelou ação neuroprotetora na Doença de Alzheimer. O objetivo desse trabalho foi avaliar a resposta neuroprotetora da Memantina em animais tratados ou não com derivação liquórica. Foram utilizados ratos machos Wistar submetidos à hidrocefalia através de injeção intracisternal de caulim, divididos em cinco grupos: controle (n=10), hidrocefálicos sem tratamento (n=10), hidrocefálicos tratados com Memantina intraperitoneal (20mg/kg/dia) (n=10), hidrocefálicos derivados (n=10), hidrocefálicos derivados tratados com Memantina (n=10). Para avaliação do tratamento foram realizados testes de comportamento (open field, monitor automático de atividade, water maze e reconhecimento de objeto), estudos histológicos e imunoistoquímicos. O tratamento da Memantina resultou em importante melhora no desenvolvimento sensoriomotor (p<0,05), maior agilidade e exploração do ambiente, preservação da memória espacial e de reconhecimento e maior capacidade de aprendizagem (p<0,05). Reduziu a reação astrocitária no córtex e na matriz germinativa (p<0,05) por imunomarcação do GFAP. Conclui-se que a Memantina oferece efeitos benéficos às estruturas que foram afetadas pelo aumento ventricular e pode ser considerada uma terapia adjuvante ao tratamento cirúrgico da hidrocefalia. / Hydrocephalus is an imbalance in the flow or absorption of cerebrospinal fluid, resulting in a dilation of the ventricular system. The treatment of hydrocephalus usually used is surgical (shunt), but not all patients can undergo surgical treatment immediately after diagnosis. With this, neuroprotective measures have been tested in order to minimize the tissue lesions involved. Memantine is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, which revealed neuroprotective action in Alzheimer\'s disease. The aim of this study was to evaluate the neuroprotective response of Memantine in animals treated with or without a shunt. Male Wistar rats were submitted to hydrocephalus by intracisternal injection of kaolin, divided into five groups: control (n = 10), hydrocephalus without treatment (n = 10), hydrocephalus treated with intraperitoneal Memantine (20mg / kg / day) (n = 10), hydrocephalus treated with shunt (n = 10), hydrocephalus treated with shunt plus Memantine (n = 10). To evaluate the treatment, behavior tests (open field, automatic activity monitor, water maze and object recognition), histological and immunohistochemical studies were performed. The treatment with Memantine resulted in a significant improvement in sensorimotor development (p <0.05), greater agility and exploration of the environment, preservation of spatial and recognition memory, and greater learning ability (p <0.05). Reduced astrocytic reaction in the cortex and germ matrix (p <0.05) by GFAP immunolabeling. It is concluded that Memantine offers beneficial effects to the structures that have been affected by the ventricular increase and can be considered an adjuvant therapy to the surgical treatment of hydrocephalus.

Neurodegenerative disorders constitute a class of diseases that express characteristic misfolded proteins that aggregate and induce neuronal toxicity and death. Huntington’s disease is one such fatal protein misfolding disease. Currently no therapeutic avenue can delay or stop the progression of the disease. In this context, there is a need to identify therapeutic pathways and drug targets that can prevent or delay pathogenesis in neurodegenerative diseases involving protein misfolding. This dissertation describes how our search for new drug targets have led us to identify protein disulfide isomerase and three unique small molecules that modulate its activity as a means to protect neuronal cells from neurodegenerative protein misfolding diseases, such as Huntington’s disease. Protein disulfide isomerase is a thiol-oxidoreductase in the endoplasmic reticulum that has garnered increased attention because of its implicated role in numerous human diseases, including cancer, human immunodeficiency virus pathogenesis, and thrombosis. Validating protein disulfide isomerase as target for neurodegenerative disorders may open up new therapeutic strategies to understand and treat these diseases. First, I describe the identification and validation of protein disulfide isomerase as a target of the neuroprotective small molecule, 16F16. I show that 16F16 is an irreversible inhibitor of protein disulfide isomerase that binds covalently to both cysteines in the active site. This inhibition is protective in cell and brain-slice models of Huntington’s disease, as well as in the brain-slice model of Alzheimer’s disease. Next, I describe the neuroprotective small molecule IBS141 that was originally incorrectly annotated with a chemical structure. I elucidate the correct structure of the active compound using analytical chemistry, revealing it to be the natural product securinine. Furthermore, I identify the binding site of securinine to protein disulfide isomerase and show that the inhibition of the protein is protective in cell and brain-slice models of neurodegenerative diseases. In addition to finding this unexpected activity of securinine, I provide a systematic roadmap to those who encounter compounds with incorrect structural annotation in the course of screening campaigns. Last, I describe the discovery of LOC14, a nanomolar, reversible, modulator of protein disulfide isomerase that protects cells and medium spiny neurons from the toxic mutant huntingtin protein. I find that this protection results from LOC14 binding adjacent to the active site and inducing protein disulfide isomerase to adopt an oxidized conformation. LOC14, has dramatically improved potency for protein disulfide isomerase over previously identified inhibitors and displays favorable pharmaceutical properties, making it an idea compound to evaluate the therapeutic potential of modulating protein disulfide isomerase in in vivo models of neurodegenerative diseases.

Introdução: A lesão da medula espinhal é uma entidade clínica grave e extremamente incapacitante. Muitos esforços estão sendo realizados para melhorar a resposta neurológica ao trauma da medula espinhal. Dentre eles, destacamos o uso de agentes farmacológicos, a descompressão e estabilização cirúrgica precoces e a hipotermia. A hipotermia pode ser induzida de forma sistêmica ou local. Várias complicações, como arritmias cardíacas, coagulopatias e infecções, foram associadas ao uso sistêmico da hipotermia. Porém, sua aplicação local demanda a necessidade de intervenção cirúrgica de emergência e manejo pós-operatório complicado. Objetivo: Avaliar o efeito neuroprotetor da hipotermia epidural em ratos. Material e método: Foram arrolados 30 ratos Wistar pesando entre 320-360 g e divididos aleatoriamente em dois grupos: o grupo da hipotermia epidural e o grupo controle, com 15 ratos cada. Uma contusão medular produzida por queda padronizada de peso de 10 g, a 25 mm de altura, usando o New York University (NYU) Impactor, foi realizada após a laminectomia em T9-10 em todos os ratos. Os ratos do grupo da hipotermia foram submetidos ao resfriamento a 9-10 °C por um período de 20 minutos, logo após a contusão medular. Os grupos foram analisados durante seis semanas quanto à função motora utilizando-se a escala BBB e o teste do plano inclinado. Ao final da sexta semana, foi realizado ainda o exame de potencial evocado motor dos ratos, cujos resultados foram comparados entre os dois grupos. Resultados: A avaliação da função motora através da aplicação da pontuação da escala BBB ao longo das seis semanas não evidenciou diferenças estatisticamente significantes entre os dois grupos. Não encontramos diferenças estatísticas na avaliação motora através da pontuação do teste do plano inclinado ao longo das seis semanas do estudo. Os valores de latência e amplitude do potencial evocado motor não mostraram diferenças estatísticas significantes entre os grupos ao final da última semana do estudo. Conclusão: A hipotermia não apresentou efeito neuroprotetor quando aplicada no sítio da lesão, logo após a contusão medular, no espaço epidural de ratos Wistar / Introduction: Spinal cord injury (SCI) is a critical and extremely disabling clinical condition. Considerable effort has been made to improve the neurological response to the spinal cord lesion. We must highlight pharmacological agents, early surgical decompression and stabilization and hypothermia. Therapeutic hypothermia can be achieved systemically or locally. Many complications have been associated to the systemic hypothermia, such as cardiac arrhythmias, coagulopathies and infection. However, local application demands surgical intervention and difficult post operative care. Objetive: To evaluate the neuroprotective effect of epidural hypothermia in rats. Methods: Wistar rats (n = 30; weighting 320-360 g) were randomized in two groups: the hypothermia and the control group, with 15 rats in each. A spinal cord lesion was produced by the standardized drop of a 10 g-weight from a height of 2,5 cm, using the New York University Impactor, after the laminectomy at the T9-10 level. Rats of the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed during six weeks using the BBB motor scores and inclined plane test. At the end of the last week, neurologic status was monitored by the motor evoked potential exam and the results were compared between the two groups. Results: Analysis of the BBB scores during the six-weeks period did not show any statistically significant difference between the two groups. We did not find any significant difference between the groups in the scores of the inclined plane test during the six-weeks period. Latency and amplitude values of the motor evoked potential exam did not show any statistically significant difference between the two groups at the end of the study. Conclusion: Hypothermia did not produce any neuroprotective effect when applied immediately after spinal cord contusion, at the injury level and in epidural space of Wistar rats

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Dentre as espÃcies do gÃnero Erythrina (Fabaceae), duas conhecidas popularmente como mulungu, E. velutina e E. mulungu, tem comprovado interesse social e econÃmico para o Brasil. E. mulungu ocorre no Sudeste, pertence à RelaÃÃo Nacional de Plantas de Interesse para o SUS (RENISUS). Jà E. velutina à uma Ãrvore amplamente utilizada no Nordeste, cuja casca do caule à utilizada tradicionalmente no tratamento da ansiedade, agitaÃÃo e insÃnia. Contudo, nÃo existe um produto farmacÃutico com qualidade agregada e estudos farmacolÃgicos dessa espÃcie para justificar seu uso medicinal. Diante do exposto, o objetivo do presente trabalho foi realizar o desenvolvimento e o controle de qualidade do extrato de Erytrhina velutina e investigar as atividades antioxidante e neuroprotetora, visando seu emprego no tratamento de doenÃa neurodegenerativa, como a DoenÃa de Parkinson (DP). Inicialmente, foi validado mÃtodo espectrofotomÃtrico para dosagem de fenÃis totais (FT) em produtos derivados de E. velutina, sendo este especÃfico, linear, preciso, exato e robusto. Foi estabelecido o mÃtodo de preparaÃÃo (estufa com circulaÃÃo e renovaÃÃo de ar â 80ÂC; 24h) e especificaÃÃes para o controle da droga vegetal. O extrato etanÃlico de E. velutina (EEEV) produzido por percolaÃÃo foi caracterizado quando ao teor de FT (155,14  3,31  EAG/mg de extrato) e perfil cromatogrÃfico por CLAE-DAD (FenÃis: hesperidina - Tr: 18,8 min; abssinina - Tr: 22,9 min; homoesperidina Tr: 31,2 min; Ãcido rizÃnico (AR) - Tr: 32,1 min e sigmoidina C - Tr: 38,6 min). O EEEV nÃo mostrou citotoxicidade no teste do MTT, mas aumentou (EEEV: 100 e 200 Âg/mL) a atividade da LDH em neutrÃfilo humano. Em cÃlulas 9L/lacZ, o EEEV (100, 400, 1000 mg/mL) reduziu significativamente a viabilidade celular, teste MTT. EEEV (0,0025 â 1 Âg/mL) e AR (0,0025 â 1 Âg/mL) nÃo foram citotÃxicos e inibiram parcialmente a neurotoxicidade induzida por 6-OHDA em cÃlulas SH-SY5Y, modelo experimental de DP, observada pela reduÃÃo significativa dos nÃveis de nitrito/nitrato. Na avaliaÃÃo do potencial antioxidante, testes DPPH e NBT, o EEEV (10 â 200 Âg/mL) apresentou atividade sequestradora de radicais livres no teste DPPH. Os resultados obtidos no presente estudo permitiram definir as condiÃÃes ideais de preparaÃÃo da droga vegetal e do extrato, os quais foram caracterizados, incluindo validaÃÃo de mÃtodo analÃtico e avaliaÃÃo farmacolÃgica, comprovando o potencial antioxidante e neuroprotetor do EEEV e AR.

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2016-04-18T18:12:36Z No. of bitstreams: 1 Stífani Machado Araujo.pdf: 2701104 bytes, checksum: db0f252b8e5b648fd9a2f147be16081a (MD5) / Made available in DSpace on 2016-04-18T18:12:36Z (GMT). No. of bitstreams: 1 Stífani Machado Araujo.pdf: 2701104 bytes, checksum: db0f252b8e5b648fd9a2f147be16081a (MD5) Previous issue date: 2016-02-19 / Doença de Parkinson (DP) é a segunda doença neurodegenerativa mais comum no mundo, afetando cerca de 1% dos adultos com mais de 60 anos. A DP está relacionada com a degeneração de neurônios dopaminérgicos principais componentes da substância negra cerebral, concomitantemente, com a disfunção do complexo I mitocondrial e o estresse oxidativo que desempenham um papel crucial na patogênese desta doença. A rotenona (ROT) é um pesticida natural e muito utilizado para induzir fenótipo de DP em modelos animais, por ser lipofílico pode atravessar facilmente a barreira hematoencefálica causando disfunção do complexo I mitocondrial e possível morte de neurônios dopaminérgicos. Dentre as várias aplicações terapêuticas dos antioxidantes, ressalta-se sua ação neuroprotetora, uma vez que o sistema nervoso central exibe uma maior vulnerabilidade e susceptibilidade aos insultos oxidativos, o γ-orizanol (ORY) é um produto natural composto por uma mistura de ésteres de ácido ferúlico extraídos a partir do óleo de farelo de arroz, e é bem descrito na literatura por possuir propriedades antioxidantes. Assim, o objetivo deste trabalho foi investigar um possível efeito neuroprotetor do γ-orizanol sobre alterações comportamentais e bioquímicas causadas pela exposição crônica de Drosophila melanogaster a rotenona. A mosca da fruta Drosophila melanogaster, é uma espécie alternativa à utilização de modelos mamíferos que vem sendo usada com bastante confiabilidade na reprodução de modelos de disfunção dopaminérgica. As moscas (de ambos os sexos) com idades compreendidas entre 1 a 5 dias de idade foram divididos em quatro grupos de 50 moscas cada um: (1) de controle, (2) ORY 25 μM, (3) ROT 500 μM, (4) ORY 25 μM + ROT 500 μM. As moscas foram concomitantemente expostos a uma dieta contendo ROT e ORY durante 7 dias de acordo com os seus respectivos grupos. Após o tratamento foram feitas as analises comportamentais e bioquimicas. Como resultados, verificamos que o ORY ofereceu proteção contra as alterações locomotoras causadas por ROT, além de prevenir a mortalidade induzida por rotenona, protegeu contra geração de estresse oxidativo e disfunções mitocondriais além de otimizar as defesas antioxidantes celulares. Nossas descobertas apontam uma restauração dos déficits colinérgicos, e nos níveis de dopamina fornecida por pelo tratamento com ORY. Em conclusão, os presentes resultados mostram que ORY é eficaz na redução da toxicidade induzida ROT em Drosophila melanogaster, o que mostrou uma ação neuroprotetora, possivelmente devido à presença dos componentes de antioxidantes tais como o ácido ferúlico. / Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, affecting about 1% of adults over 60 years. The DP is linked to the degeneration of dopaminergic neurons main components of the substantia nigra brain, concurrently with mitochondrial complex I dysfunction and oxidative stress play a crucial role in the pathogenesis of this disease. The rotenone (ROT) is a natural pesticide, and used to induce PD phenotype in animal models, being lipophilic can easily cross the blood-brain barrier dysfunction causing mitochondrial complex I and possible death of dopaminergic neurons. Among the various therapeutic applications of antioxidants, it emphasizes its neuroprotective action, as the central nervous system displays a greater vulnerability and susceptibility to oxidative insults, the γ-oryzanol (ORY) is a natural product composed of a mixture of esters ferulic acid derived from rice bran oil, and is well described in the literature to possess antioxidant properties. The objective of this study was to investigate a possible neuroprotective effect of ORY on behavioral and biochemical changes caused by chronic exposure of Drosophila melanogaster the rotenone. The fly fruit Drosophila melanogaster, is an alternative species to the use of mammalian models that have been used quite reliable reproduction of dopaminergic dysfunction models. The flies (male and female) between the ages of 1 to 5 days of age were divided into four groups of 50 flies each: (1) control, (2) ORY 25 μM, (3) ROT 500 μM ( 4) ORY 25 μM + ROT 500 μM. The flies were simultaneously exposed to a diet containing ROT and ORY for 7 days according to their respective groups. After treatment were made behavioral and biochemical analysis. As a result, we find that the ORY offered protection against locomotor changes caused by ROT, and to prevent the mortality induced by rotenone, protected against the generation of oxidative stress and mitochondrial dysfunction and optimize cellular antioxidant defenses. Our findings point to a restoration of cholinergic deficits, and dopamine levels provided by the treatment ORY. In conclusion, the present results show that ORY is effective in reducing the ROT induced toxicity in Drosophila melanogaster, which showed a neuroprotective effect, possibly due to the presence of antioxidants components such as ferulic acid.

[Truncated abstract] Clinical therapeutic agents to directly inhibit ischaemic neuronal death are presently unavailable. One approach to developing therapeutics is based upon the identification of proteins up-regulated by 'preconditioning', a natural adaptive response utilised by the neural cells to counter damaging insults, such as ischaemia. Thus, my project aimed to firstly identify proteins differentially expressed following erythropoietin (EPO) mediated neuronal preconditioning and secondly to assess whether any of these proteins possessed neuroprotective activity using in vitro ischaemia like models. To achieve the first aim, it was shown that in vitro neuronal EPO preconditioning could: (i) induce cell signal changes in neuronal cultures, (ii) protect neurons against in vitro ischaemia and (iii) induce differential protein expression. Overall, 40 differentially expressed proteins were identified in cortical neuronal cultures following EPO preconditioning. In order to investigate the neuroprotective or neurodamaging activity of proteins induced by EPO preconditioning I developed an adenoviral expression system for use in neuronal cultures. To this end, I assessed the suitability of four promoters (cytomegalovirus [CMV], rous sarcoma virus [RSV], human synapsin 1 [hSYN1], rat synapsin 1 [rSYN1]) previously used to express proteins in neuronal cultures and demonstrated the superiority of the RSV promoter for this purpose. ... Finally, in order to validate this adenoviral expression system, I over-expressed the anti-apoptotic protein Bcl-XL in neuronal cultures and subsequently confirmed its neuroprotective activity in the in vitro ischaemia and oxidative stress models used in my project. Using this adenoviral vector system and the in vitro oxidative stress model I assessed a number of proteins up-regulated by EPO preconditioning. The results of this preliminary study indicated that cyclophilin A (CyPA), peroxiredoxin 2 (PRDX2) and superoxide dismutase 1 (SOD1) over-expression were neuroprotective. It was subsequently verified that adenoviral mediated over-expression of CyPA and PRDX2, v but not SOD1 in cortical neuronal cultures could protect neurons from in vitro ischaemia. I also confirmed that CyPA mRNA increased in the rat hippocampus in response to 3 minutes of global cerebral ischaemia. Interestingly, an increase in CyPA, PRDX2 or SOD1 protein was not observed in the same experimental paradigm. To investigate CyPA's mode of action I confirmed that cultured neurons, but not astrocytes, express the CyPA receptor, CD147. It was also demonstrated that administration of exogenous CyPA protein to neuronal cultures could protect neurons against oxidative and ischaemic injury. I further demonstrated that exogenous administration of CyPA induces a rapid and transient activation of the extracellular signal-regulated kinase (ERK) 1/2 pathway in neuronal cultures. From this observation, I have proposed that the extracellular mediated neuroprotective activity of CyPA occurs via CD147 receptor signalling and activation of ERK1/2 pro-survival pathways. Based on the findings reported in this thesis, the neuroprotective activities of PRDX2 and CyPA warrant further investigation as targets for the development of new therapies to treat cerebral ischaemia.

Stroke is the 3rd leading cause of death and the leading cause of major disability worldwide. Currently, there are no neuroprotective drugs approved for the acute treatment of ischaemic stroke. The vast majority of stroke therapeutics failed in clinical trials due to toxic side effects and/or a clinically irrelevant therapeutic window. This thesis is focused on exploiting the delayed neurodegeneration that occurs in the compromised penumbra, as these cells may be capable of being saved by therapeutic intervention in a clinically obtainable window. In order to investigate the ischaemic cascade and be able to draw conclusions that are applicable to humans, the international gold standard animal model for cerebral ischaemia, the filament insertion middle cerebral artery occlusion (MCAO) model, was established at the University of Otago. This model was validated under new laboratory conditions and employed adult male Sprague Dawley rats. After testing multiple occlusion lengths, it was concluded that a 2hr ischaemic period was sufficient to produce a consistent infarct of optimal size. It has been well documented that neuroinflammation contributes to much of the delayed progression of neural injury post-stroke. Therefore, the catechin (-)-epigallocatechin gallate (EGCG), which is an anti-inflammatory, anti-oxidant and free-radical scavenging agent was investigated in the MCAO model of stroke. 50mg/kg i.p. of EGCG or saline was administered immediately post-MCAO and animals were sacrificed at 72hr post-filament insertion. The results confirmed that treatment with EGCG was neuroprotective and non-toxic. However, EGCG also induced an over 50% increase in the risk of haemorrhagic conversions. The anti-platelet effects of EGCG and lack of toxicity suggests that the catechin may prove to be an efficacious prophylactic for stroke. The contrary findings for EGCG treatment led to the re-evaluation of the neuroinflammatory pathway for alternate mechanisms to target therapeutic interventions. The temporal profile of the primary inducible enzymes nitric oxide synthase (NOS), cyclooxygenase (COX) and arginase (and their isoforms) were quantified 0, 3 and 7 days post-stroke. In both hemispheres, total NOS activity exhibited a significant and sustained up-regulation to 7 days post-occlusion. In the ipsilateral hemisphere at least half of the total increase was accounted for by inducible NOS (iNOS) expression. Arginase, which competes with NOS for L-arginine, demonstrated a delayed but significant increase in activity by day 7 in the infarcted hemisphere, thereby correlating well with the downward slope of NOS activity (illustrating the switch in the conversion pathway). COX activity was observably increased in the ipsilateral hemisphere, but the up-regulation did not reach significance by day 7. Alternately, the contralateral hemisphere displayed a significant decrease in activity by day 3. These results give conclusive evidence that the contralateral hemisphere is NOT an appropriate internal control and imply that NOS and COX inhibitors may prove to be efficacious for a much longer therapeutic window than current treatments. However, the delayed induction of COX activity may also indicate that this enzyme has a finite therapeutic window, as it may also stimulate remodelling of surviving neural networks. The prolonged up-regulation of inflammatory mediators implies that there may be an induction of an autoimmune component to the response. Therefore, the thymus (T) lymphocyte activation was quantified up to 14 days post-stroke. Cluster of differentiation (CD) 3⁺ T lymphocytes (equally contributed to by CD4⁺ and CD8⁺ T cells) exhibited a significant and sustained up-regulation in the infarcted region from day 3 up to at least day 14 post-ischaemia. Quantitative analysis of all cells present post-stroke determined that immune cells make up an average of 73% of all cells present in the 'peak' ischaemic areas. The CD4⁺ T helper cell response was delineated by double immunohistochemical labelling. Interferon-γ positively labelled with CD4⁺ T cells at days 3, 7 and 14 post-insult detailing a Th1-driven pro-inflammatory response. This evidence indicates that the autoimmune response is critical post-ischaemia and that it may be highly susceptible to modification by anti-inflammatory therapeutic intervention. The primary downstream effect of the pro-inflammatory/immune cascade is apoptosis. The main organelle responsible for the 'go, no go' response to apoptotic factors is the mitochondria. In order to distinguish whether mitochondrial dysfunction was initiated shortly after ischaemia induction or if it was delayed, like the inflammatory/immune response, to a clinically relevant window, the temporal profile of mitochondrial complex inactivation was studied. It was found that mitochondrial membrane viability was impaired by day 3, followed by a significant decrease in respiratory complex activation and an increase in tissue injury by oxidative stress by 7 days post-ischaemia. These results indicate that targeting the early decrease in membrane viability or mitochondrial permeability transition pore opening combined with anti-apoptotic therapeutics, may attenuate the proceeding mitochondrial impairment in oxidative phosphorylation, reactive oxygen species generation and subsequent cell death cascades. The current investigations into the temporal profile and quantitative contributions of the inflammatory, immune and apoptotic mechanisms post-stroke highlight potential strategies for modulation by acute stroke therapeutics. Furthermore, the general knowledge amassed from these studies dictates the necessity of a new approach to therapeutic intervention. The acknowledgement of so many contributing systems suggests that in addition to a thrombolytic, a combination therapy involving multiple neuroprotectants should be employed to account for the multifaceted nature of the sequelae of ischaemic stroke.

Thesis (M.Sc.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Centre for Neuroscience. Title from pdf file main screen (viewed on January 27, 2010). Includes bibliographical references.

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

In order to understand the possible mechanisms in the glaucoma-related retinopathy, the role of the vasoconstrictor, endothelin-1 (ET-1), receptor for advanced glycation end-products (RAGE) as well as its ligand, Aβ in the degeneration of retinal ganglion cells (RGCs) were studied in experimental models. In addition, the relationship of ET-1, RAGE and Aβ for the RGC protective mechanism of Lycium Barbarum (LB) was also investigated. In the first part, ET-1 together with its receptors, ETA and ETB, were studied to understand their possible roles in chronic ocular hypertension (COH). The neuronal protective mechanism of LB was also determined by using a well established COH rat model. In normal rats, ET-1 and its receptors, ETA and ETB, were distributed in the retina, vasculature and optic nerve. Interestingly, ET-1 expression was up-regulated after COH. LB could decrease the expression of ET-1 and regulate its receptors (up-regulation of ETB and down-regulation of ETA in vasculature; up-regulation of ETA and down-regulation of ETB in RGCs) under the condition of COH. These data suggested that the RGC protective mechanism of LB might be related to its ability to regulate the biological effects of ET-1. To investigate the pathogenic effect of ET-1 in glaucoma, in the second part, we used transgenic mice with over-expression of ET-1 on endothelial cells (TET-1 mice). We found that beginning at 10-12 months, TET-1 mice showed a progressive retinal degeneration (loss of RGCs associated with neurons in the inner nuclear layer and outer nuclear layer of the retina) without elevation of the intraocular pressure (IOP). The data demonstrated that TET-1 mice may serve as a potential model to investigate the role of endothelial ET-1 in the pathogenesis of normal tension glaucoma and other degenerative retinopathy. To investigate whether LB plays a role on neuronal protection other than in COH, in the third part, we used an acute ocular hypertension (AOH)-induced ischemia mouse model. We found that LB could rescue RGCs under AOH insult, associating with blood vessel protection (decreasing the damage of blood-retinal-barriers and rescuing the survival of endothelial cells and pericytes) and inhibiting retinal gliosis. We also found the protective mechanism of LB was closely correlated with down-regulation of the expression of RAGE, ET-1, APP (amyloid precursor protein), AGE (advanced glycation end-product) as well as Aβ; therefore to reduce the damage effects of these RAGE-mediated reactions to the retinal neurons, blood vessels and glial cells involved in the ischemic insult. Taken together, the present study demonstrated that TET-1 mice may be a potential model for investigating the role of ET-1 in degenerative retinopathies, such as normal tension glaucoma. We also showed the neuronal protective mechanism of LB in vivo was associated with inhibiting the biological effect of ET-1 and down-regulating the damage signaling pathways mediated by the activation of RAGE and its ligands (AGE and Aβ). These results provided further understandings in the mechanism of the glaucoma-related retinopathy. In addition, LB could be a neuroprotective agent to the retina following both chronic and acute injuries. / published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy