A neuroproteção é um dos tópicos mais relevantes aplicados à neurociência. As junções comunicantes (JC), formadas pelas conexinas (Cx) estão envolvidas na neurodegeneração após lesão. Estudos com animais KO apresentam resultados contraditórios sobre papel das JCs. O objetivo deste trabalho foi analisar o papel das Cxs a partir do trauma mecânico na retina, modelo que permite a visualização do foco, penumbra, e áreas adjacentes à lesão. Observamos regulação distinta das Cx36 e Cx43 durante a neurodegeneração. A Cx36 não se alterou e a Cx43 apresentou desorganização e aumento da imunorreatividade após 7 dias, concomitantemente com GFAP. Células amácrinas apoptóticas encontram-se acopladas a células vizinhas por Cx36. O papel funcional das JCs foi avaliado, utilizando bloqueadores, para verificar a viabilidade/morte de células. Carbenoxolone (CBX), reduziu o espalhamento da apoptose, após 4h, enquanto a quinina, teve o mesmo efeito após 1h. A distribuição de núcleos apoptóticos confirmou que a utilização de bloqueadores de JCs reduz a propagação da apoptose. A quinina, mas não o CBX, diminuiu a expressão de caspases iniciais e efetoras. O controle da permeabilidade de canais de JCs pode participar de estratégias de neuroproteção. / The neuroprotection stands out as one of the most pursued hot topics in applied neurosciences. The gap junctions (GJ), formed by connexin (Cx) are involved in neurodegeneration injury. Studies using KO animal models endowed apparently contradictory results in relation to the role of coupling in neuroprotection. The aim of this study was to analyze the role of Cx-mediated communication in focal lesion induced by mechanical trauma in the retina, a model that alow the visualization of the focus, penumbra and adjacent areas. We observed distinct regulation of Cx36 and Cx43 during neurodegeneration. The Cx36 did not change during the lesion progression and Cx43 showed disorganized pattern and upregulated after 7 days, the same as GFAP. Apoptotic amacrine cells are coupled with health neighborhood cells by Cx36. The functional role of GJ was evaluated using blockers to verify the viability/cell death. Carbenoxolone (CBX) reduced the spread of apoptosis after 4h while quinine had the same effect after 1h. The distribution of apoptotic nuclei confirmed that the use of GJ blockers reduced the propagation of apoptosis. Quinine, but not CBX, decreases initial and effector caspases expression. The control of GJ channels permeability can participate in neuroprotection strategies.

by Zhang Chun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 154-197). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstract in Chinese and English.

Ng, Tsz Kin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 151-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

年齡相關性黃斑變性（AMD）是發展國家高齡人群中不可逆盲的首要原因。在AMD患者中，即使在改變生活模式或進行治療后，其滲出性亞型仍導致超過80% 的病例出現嚴重視力喪失及法定盲。息肉狀脈絡膜血管病變 （PCV）是一種與滲出性AMD在臨床表型上存在相同之處的黃斑病變，它的典型病變被定性為眼底血管螢光造影時出現息肉狀的病灶。近年PCV被認為是滲出性AMD亞型中的一種，因為兩者共享相同的基因成份及環境因素。然而，PCV曾經被認為是與滲出性AMD截然不同的一種疾病，由於兩者的臨床表現並不一致。另外，PCV病人相對年輕，多為亞洲人，以及對光動力治療和抗血管內皮生長因子治療存在不同的反應。一個明確的鑒別診斷可以更好的輔助臨床醫生對患有這些疾病的老年病人進行管理，然而兩者是相同還是不同的疾病種類仍是一個具爭議性的議題。 / CFH 基因和ARMS2/HTRA1位點已被全基因組相關性研究及相關的分子學研究定位為AMD候選基因。鑒於FPR1基因的協調吞噬性白細胞激活及遷移的功能，它可能是一個新的AMD候選基因。本論文評估在滲出性AMD和PCV中FPR1作為一個新的疾病基因基因的可能，獲取滲出性AMD和PCV病人中的CFH，ARMS2，HTRA1和FPR1基因檔案，同時研究在ARMS2/HTRA1位點中基因型和疾病表型的關聯性，以此從基因學方面鑑別滲出性AMD與PCV。 / 本研究在滲出性AMD，PCV病例和對照人群中使用聚合酶鏈反應和直接測序法進行ARMS2， HTRA1， CFH 和FPR1基因篩查。本研究發現滲出性AMD和PCV之間存在不同的基因型分佈，關聯模式以及基因效應值。 / 在HTRA1的多態性中，rs11200638，rs2672598, rs1049331 和 rs2293870 在滲出性AMD和PCV之間表現出鑒別性關聯 （p < 0.001）。其中rs11200638 (p = 1.48×10⁻⁴) and rs2672598 (p = 2.27×10⁻³) 在滲出性AMD病人中相互校正后仍保持各自的顯著性，但rs2672598 未能在PCV病人中保持顯著性(p = 0.20)。並且本研究發現攜帶rs11200638和 rs2672598聯合基因型AA-CC 的病人更傾向是滲出性AMD病人，與PCV相比幾率高11.7倍。 / 在ARMS2中，有11個基因多態性與滲出性AMD和PCV存在顯著性的相關。在與rs11200638校正后，rs10490924保持和滲出性AMD的顯著相關性(p = 0.011)，但PCV中未能保持(p = 0.077)。同時，元分析結果顯示ARMS2 rs10490924和HTRA1 rs11200638不同人群的PCV中的等位基因相關性是一致的。 / 在FPR1中，rs78488639與滲出性AMD (p = 0.049, 比值比 (OR) = 2.05, 95% 信賴區間（CI）: 1.014.14)和PCV (p = 0.016, OR = 2.27, 95%CI: 1.154.47)的疾病風險存在顯著的相關性。多態性rs104229的G等位基因純合子和滲出性AMD存在顯著相關(p = 0.039, OR = 2.27, 95%CI: 1.084.74)，但在PCV中未發現相關性(p = 0.24)。多態性rs2070746 AMD (p = 0.021, OR = 0.57, 95%CI: 0.35 0.91)和rs867229 (p = 0.0091, OR = 0.54, 95%CI: 0.340.86) 的雜合子基因型與滲出性AMD相關，但在PCV中未發現相關性。與此同時，本研究在上述多態性中發現滲出性AMD和PCV之間不同的基因型分佈。 / 本研究發現在滲出性AMD和PCV病人中FPR1 rs78488639和CFH rs800292存在顯著的相互作用（ORs > 4）。兩個多態性之間的相互作用提高滲出性AMD和PCV的疾病風險，而不是僅對其中之一起作用。 / ARMS2 多態性 rs10490924 (A69S, 205G>T, pAMD = 1.01×10⁻²⁹ OR = 7.91, 95% CI: 4.93 - 12.67; pPCV = 8.25×10⁻⁷, OR = 3.51, 95% CI: 1.98 - 5.03), HTRA1 多態性rs11200638 (-625G>A, pAMD = 9.88×10⁻²⁸, OR = 6.95, 95% CI: 4.37 - 11.06; pPCV = 8.02×10⁻⁶, OR = 2.82, 95%CI: 1.77 - 4.47), CFH 多態性rs800292 (V62I, 184G>A, pAMD = 9.00×10⁻⁴ , OR = 0.58, 95% CI: 0.42 0.79; pPCV = 0.011, OR = 0.66, 95% CI: 0.49 0.90) and FPR1 多態性rs78488639 (L97M, 289C>A, pAMD = 0.049, OR = 2.05, 95% CI: 1.01 - 4.14; pPCV = 0.016, OR = 2.27, 95% CI: 1.15 - 4.47)代表各自基因的最強相關性。此外，元分析揭示了在不同種族人群PCV中的等位基因相關性顯著並且一致(ORtotal = 2.14, 95% CI: 1.97 2.33, ORtotal = 2.34, 95% CI: 1.98 2.76 and ORtotal = 0.49, 95% CI: 0.44 0.56)。表型-基因型分析發現ARMS2/HTRA1 的風險基因型和較差的治療反應呈正相關性(p = 0.04)。另外，本研究在滲出性AMD中發現HTRA1 rs11200638和吸煙的聯合作用。然而，在PCV中未觀察到次聯合作用，這可能提示兩者間存在不同的疾病機制。 / 本論文提出FPR1基因是一個新的滲出性AMD和PCV候選基因，揭示了ARMS2，HTRA1，CFH和FPR1在滲出性AMD和PCV間顯著並且一致的相關性， 提供鑒別兩者的基因學證據，闡明了ARMS2/HTRA1 的風險基因型和較差的治療反應之間的相關性以及顯示了吸煙在滲出性AMD和PCV之間的不同影響。然而，由於兩者間基因關聯的趨勢一致，目前尚未能清晰界定兩者的不同。因此，要進一步明確鑒別滲出性AMD和PCV，還需要進行不同種族的複製研究，以及更重要的是，尋找特定的PCV基因以鑒別兩個不同疾病。 / Age-related macular degeneration (AMD) is the leading cause of irreversible blindness for the elderly in developed countries. Its exudative subtype accounts for more than 80% of severe visual loss or legal blindness in AMD patients regardless of modified lifestyle and therapeutic treatments. Polypoidal choroidal vasculopathy (PCV) is a macular disorder characterized by typical polypoidal lesions on fundus angiograhpy and sharing similar phenotype with exudative AMD. PCV was suggested as a distinct disease from exudative AMD based on different clinical features in ophthalmic imaging. Furthermore, PCV patients tend to be younger and more prevalent in Asian, and have different responses to photo-dynamic therapy and anti-vascular endothelial growth factor treatments, compared to exudative AMD patients. Howerver, it has also been suggested that PCV could be a subtype of exudative AMD mainly because of their common genetic and environmental factors. Therefore, genetic differentiation between exudtive AMD and PCV might assist clinicans to determine the condition. / The complement factor H (CFH) gene, and age-related maculopathy susceptibility 2 (ARMS2)/high temperature requirement factor A1 (HTRA1) locus have been mapped for AMD by genome-wide association studies (GWAS) and subsequent molecular investigations. The formyl peptide receptor 1 (FPR1) gene, which mediates trafficking and activation of phagocytic leukocytes, is related to the AMD-associated inflammatory condition. This thesis aims to evaluate FPR1 as a novel disease gene for exudative AMD and PCV, to compare the genetic profiles of ARMS2, HTRA1, CFH, and FPR1 in exudative AMD and PCV, to investigate the correlation of ARMS2/HTRA1 genotypes with disease phenotypes, and to differentiate these two disorders throught the genomic compositions. / Case-control association studies were conducted on ARMS2, HTRA1, CFH and FPR1 in exudative AMD and PCV patients of our Hong Kong Chinese cohort using polymerase chain reaction and direct sequencing. We observed different genotypic distributions (p < 0.05), association patterns and effect sizes between these two diseases. / In HTRA1 polymorphisms, rs11200638, rs2672598, rs1049331 and rs2293870 showed differential associations between exudative AMD and PCV (p < 0.001). Both rs11200638 (p = 1.48×10⁻⁴) and rs2672598 (p = 2.27×10⁻³) remained significant after adjusting for each other in exudative AMD, whereas rs2672598 was not significantly associated with PCV (p = 0.20). The joint genotype AA-CC constructed by the risk alleles of these rs11200638 and rs2672598 were prone to exudative AMD, conferring an 11.7-fold higher risk (p = 4.00×10⁻³) when compared to PCV. / In ARMS2, 11 single nucleotide polymorphisms (SNPs) showed significant associations with both exudative AMD and PCV. After adjusting for rs11200638, ARMS2 rs10490924 remained significantly associated with exudative AMD (p = 0.011), but not with PCV (p = 0.077). / In FPR1, SNP rs78488639 significantly increased the risk to exudative AMD (p = 0.049, odds ratio (OR) = 2.05, 95% confidence interval (CI): 1.014.14) and PCV (p = 0.016, OR = 2.27, 95%CI: 1.154.47). The homozygous G allele of rs1042229 was associated with exudative AMD (p = 0.039, OR = 2.27, 95%CI: 1.084.74), but not with PCV (p = 0.24). The heterozygous genotypes of rs2070746 and rs867229 were associated with exudative AMD (p = 0.021, OR = 0.57, 95%CI: 0.35 0.91; p = 0.0091, OR = 0.54, 95%CI: 0.340.86, respectively), but not with PCV. / Significant interaction was identified between FPR1 rs78488639 and CFH rs800292, with joint ORs > 4 folds for both exudative AMD and PCV. Interactions between FPR1 rs78488639 with CFH rs800292 enhance risks to both AMD and PCV, not just one of them. / Overall, the ARMS2 rs10490924 (A69S, 205G>T, pAMD = 1.01×10⁻²⁹, OR = 7.91, 95% CI: 4.93 - 12.67; pPCV = 8.25×10⁻⁷, OR = 3.51, 95% CI: 1.98 - 5.03), HTRA1 rs11200638 (-625G>A, pAMD = 9.88×10⁻²⁸, OR = 6.95, 95% CI: 4.37 - 11.06; pPCV = 8.02×10⁻⁶, OR = 2.82, 95%CI: 1.77 - 4.47), CFH rs800292 (V62I, 184G>A, pAMD = 9.00×10⁻⁴ , OR = 0.58, 95% CI: 0.42 0.79; pPCV = 0.011, OR = 0.66, 95% CI: 0.49 0.90) and FPR1 rs78488639 (L97M, 289C>A, pAMD = 0.0487, OR = 2.05, 95% CI: 1.01 - 4.14; pPCV = 0.0161, OR = 2.27, 95% CI: 1.15 - 4.47) were responsible for the strongest association in each gene. Moreover, meta-analysis revealed a consistent and significant association of the ARMS2/HTRA1 locus with PCV in different ethnic cohorts (OR{U+209C}{U+2092}{U+209C}{U+2090}{U+2097} = 2.14, 95% CI: 1.97 2.33, OR{U+209C}{U+2092}{U+209C}{U+2090}{U+2097} = 2.34, 95% CI: 1.98 2.76 and {U+209C}{U+2092}{U+209C}{U+2090}{U+2097} = 0.49, 95% CI: 0.44 0.56, respectively). The phenotype-genotype analysis implicated a positive correlation between ARMS2/HTRA1 risk genotype and a worse response to treatment (p = 0.04) in our exudative AMD patients. In addition, joint effects between cigarette smoking and HTRA1 rs11200638 was found in exudative AMD group. However, this effect was not significant in PCV group, which might implicate a different disease mechanism. / This thesis attempts to dissect the genetic profiles of exudative AMD and PCV. Results in this thesis suggest FPR1 as a novel candidate gene for exudative AMD and PCV, reveal a significant and consistent association of ARMS2, HTRA1, CFH and FPR1 with both exudative AMD and PCV, provide evidences for genetic differentiation of these two disorders, demonstrate a significant correlation between ARMS2/HTRA1 genotypes and response to treatment, and indicate different influence of smoking in exudative AMD and PCV. However, definite differentiation between exudative AMD and PCV was limited because of the same trend of associations between these two disorders. Therefore, replication studies in other enthic populations are necessary, and identification of PCV-specific genes/polymorphisms could further differentiate PCV from exudative AMD. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liang, Xiaoying. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 124-143). / Abstract also in Chinese. / Title page --- p.i / Abstract --- p.iii / 摘要 --- p.vii / Acknowledgements --- p.xii / Table of Contents --- p.xiii / List of Figures --- p.xix / List of Tables --- p.xxi / Abbreviations --- p.xxiv / Publications --- p.xxvii / Conference Presentations --- p.xxviii / Chapter Chapter 1: --- Introduction / Chapter 1.1. --- Normal retinal architecture --- p.1 / Chapter 1.2. --- Age-related retinal changes --- p.3 / Chapter 1.3. --- Age-related macular degeneration (AMD) --- p.7 / Chapter 1.3.1. --- Classification, clinical manifestation and disease course --- p.7 / Chapter 1.3.2. --- Exudative AMD and therapeutic strategies --- p.9 / Chapter 1.3.3. --- Pathology of AMD --- p.10 / Chapter 1.3.4. --- Risk factors and associated pathogenesis --- p.12 / Chapter 1.3.4.1. --- Age --- p.12 / Chapter 1.3.4.2. --- Ethnicity --- p.13 / Chapter 1.3.4.3. --- Oxidative stress --- p.13 / Chapter 1.3.4.3.1. --- Reactive oxygen species and AMD --- p.14 / Chapter 1.3.4.3.2. --- Antioxidants --- p.15 / Chapter 1.3.4.3.3. --- Association of oxidation genes with AMD --- p.16 / Chapter 1.3.4.4. --- Inflammation --- p.16 / Chapter 1.3.4.4.1. --- Complement in AMD --- p.17 / Chapter 1.3.4.4.2. --- The potential role of formyl peptide receptor 1 (FPR1) in AMD --- p.19 / Chapter 1.3.4.5. --- Genetic predisposition --- p.19 / Chapter 1.3.4.5.1. --- Complement factor H --- p.21 / Chapter 1.3.4.5.2. --- The 10q26 locus --- p.22 / Chapter 1.3.4.5.3. --- Phenotype-genotype correlation --- p.23 / Chapter 1.4. --- Comparisons between exudative AMD and Polypoidal choroidal vasculopathy --- p.24 / Chapter 1.4.1. --- History --- p.25 / Chapter 1.4.2. --- Natural course --- p.26 / Chapter 1.4.3. --- Epidemiological factors --- p.27 / Chapter 1.4.3.1. --- Ethnicity --- p.27 / Chapter 1.4.3.2. --- Gender --- p.27 / Chapter 1.4.3.3. --- Age --- p.28 / Chapter 1.4.3.4. --- Risk factors --- p.28 / Chapter 1.4.4. --- Clinical manifestation and histopathological features --- p.29 / Chapter 1.4.5. --- Genetic determinants --- p.29 / Chapter 1.4.5.1. --- Genes with common associations --- p.30 / Chapter 1.4.5.2. --- Genes not have common association --- p.32 / Chapter 1.4.6. --- Response to treatments --- p.32 / Chapter 1.5. --- Objectives and research prospects --- p.33 / Chapter Chapter 2: --- Materials and Methods / Chapter 2.1. --- Polymorphism identification in ARMS2, HTRA1, FPR1 and CFH --- p.39 / Chapter 2.1.1. --- Study subjects --- p.39 / Chapter 2.1.1.1. --- Diagnostic features of AMD and PCV --- p.39 / Chapter 2.1.1.2. --- Control subjects --- p.40 / Chapter 2.1.2. --- Laboratory methods --- p.40 / Chapter 2.1.2.1. --- DNA extraction and quantification --- p.40 / Chapter 2.1.2.2. --- Genotyping --- p.41 / Chapter 2.1.2.2.1. --- Polymerase chain reaction (PCR) and agrose gel electrophoresis --- p.41 / Chapter 2.1.2.2.2. --- DNA sequencing --- p.42 / Chapter 2.1.3. --- Statistical analysis --- p.43 / Chapter 2.1.3.1. --- Genotypic association analysis --- p.43 / Chapter 2.1.3.2. --- Haplotype association analysis --- p.43 / Chapter 2.1.3.3. --- Logistic regression analysis --- p.44 / Chapter 2.1.3.4. --- Joint effect analysis --- p.44 / Chapter 2.1.3.5. --- Meta-analysis --- p.45 / Chapter 2.1.3.6. --- Statistical power calculation and sample size --- p.45 / Chapter 2.2. --- Phenotype-genotype correlation in ARMS2/HTRA1 locus --- p.46 / Chapter 2.2.1. --- Patient recruitment --- p.46 / Chapter 2.2.2. --- Genotyping --- p.46 / Chapter 2.2.3. --- Outcome measurement --- p.46 / Chapter 2.2.4. --- Statistical analysis --- p.47 / Chapter Chapter 3: --- Results / Chapter 3.1. --- The age and gender distribution in study subjects --- p.57 / Chapter 3.2. --- The HTRA1 sequencing in exudative AMD and PCV --- p.57 / Chapter 3.2.1. --- Polymorphism identification and genotypic association --- p.57 / Chapter 3.2.2. --- Haplotype structure and Haplotype-based association analysis --- p.59 / Chapter 3.2.3. --- Joint genotype analysis --- p.59 / Chapter 3.3. --- Differential association of exudative AMD and PCV with the ARMS2/HTRA1 locus --- p.60 / Chapter 3.3.1. --- Genotypic association --- p.60 / Chapter 3.3.2. --- Haplotype analysis --- p.62 / Chapter 3.3.3. --- Logistic regression --- p.63 / Chapter 3.3.4. --- Meta-analysis of ARMS2/HTRA1 association with PCV --- p.64 / Chapter 3.3.5. --- In-position OR plot --- p.64 / Chapter 3.4. --- FPR1 and CFH in exudative AMD and PCV --- p.65 / Chapter 3.4.1. --- Polymorphism identification and genotypic association --- p.65 / Chapter 3.4.2. --- Haplotype analysis of FPR1 --- p.66 / Chapter 3.4.3. --- The association of CFH rs800292 --- p.67 / Chapter 3.4.4. --- Joint effect analysis of the CFH and FPR1 genes --- p.67 / Chapter 3.4. --- Phenotype-genotype correlation in ARMS2/HTRA1 locus --- p.68 / Chapter 3.4.1. --- Distribution of age and bilaterality --- p.69 / Chapter 3.4.2. --- Greatest linear dimension of CNV lesion in exudative AMD --- p.69 / Chapter 3.4.3. --- Response to treatment in exudative AMD --- p.69 / Chapter 3.4.4. --- Recurrence in PCV --- p.70 / Chapter 3.4.5. --- Smoking status --- p.70 / Chapter Chapter 4: --- Discussion / Chapter 4.1. --- Age and gender distribution --- p.104 / Chapter 4.2. --- Genetic differentiation in ARMS2/HTRA1 locus --- p.S104 / Chapter 4.2.1. --- SNPs with common association --- p.106 / Chapter 4.2.2. --- SNPs with different association S --- p.106 / Chapter 4.2.3. --- Comparison with previous studies C --- p.107 / Chapter 4.2.4. --- Sample size S --- p.109 / Chapter 4.3. --- The FPR1 gene in exudative AMD and PCV --- p.110 / Chapter 4.4. --- Interaction between FPR1 and CFH --- p.112 / Chapter 4.5. --- Correlation between phenotypes and genotypes --- p.113 / Chapter 4.6. --- Common and rare variants for complex disease --- p.114 / Chapter 4.6.1. --- The debate of common disease common variant versus common disease rare variant --- p.115 / Chapter 4.6.2. --- Candidate gene screening versus geno-wide association study --- p.117 / Chapter 4.6.3. --- Common variants versus rare variants in 10q26 locus --- p.118 / Chapter 4.6.3.1. --- Common variants --- p.119 / Chapter 4.6.3.2. --- Rare variants --- p.120 / Chapter Chapter 5: --- Conclusions and future prospects --- p.122 / Chapter Chapter 6: --- References --- p.124

No description available.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2007. / Härtill 5 uppsatser.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2009. / Title from first page of PDF file (viewed on June 10, 2009). Includes bibliographical references.

A neuroproteção é um dos tópicos mais relevantes aplicados à neurociência. As junções comunicantes (JC), formadas pelas conexinas (Cx) estão envolvidas na neurodegeneração após lesão. Estudos com animais KO apresentam resultados contraditórios sobre papel das JCs. O objetivo deste trabalho foi analisar o papel das Cxs a partir do trauma mecânico na retina, modelo que permite a visualização do foco, penumbra, e áreas adjacentes à lesão. Observamos regulação distinta das Cx36 e Cx43 durante a neurodegeneração. A Cx36 não se alterou e a Cx43 apresentou desorganização e aumento da imunorreatividade após 7 dias, concomitantemente com GFAP. Células amácrinas apoptóticas encontram-se acopladas a células vizinhas por Cx36. O papel funcional das JCs foi avaliado, utilizando bloqueadores, para verificar a viabilidade/morte de células. Carbenoxolone (CBX), reduziu o espalhamento da apoptose, após 4h, enquanto a quinina, teve o mesmo efeito após 1h. A distribuição de núcleos apoptóticos confirmou que a utilização de bloqueadores de JCs reduz a propagação da apoptose. A quinina, mas não o CBX, diminuiu a expressão de caspases iniciais e efetoras. O controle da permeabilidade de canais de JCs pode participar de estratégias de neuroproteção. / The neuroprotection stands out as one of the most pursued hot topics in applied neurosciences. The gap junctions (GJ), formed by connexin (Cx) are involved in neurodegeneration injury. Studies using KO animal models endowed apparently contradictory results in relation to the role of coupling in neuroprotection. The aim of this study was to analyze the role of Cx-mediated communication in focal lesion induced by mechanical trauma in the retina, a model that alow the visualization of the focus, penumbra and adjacent areas. We observed distinct regulation of Cx36 and Cx43 during neurodegeneration. The Cx36 did not change during the lesion progression and Cx43 showed disorganized pattern and upregulated after 7 days, the same as GFAP. Apoptotic amacrine cells are coupled with health neighborhood cells by Cx36. The functional role of GJ was evaluated using blockers to verify the viability/cell death. Carbenoxolone (CBX) reduced the spread of apoptosis after 4h while quinine had the same effect after 1h. The distribution of apoptotic nuclei confirmed that the use of GJ blockers reduced the propagation of apoptosis. Quinine, but not CBX, decreases initial and effector caspases expression. The control of GJ channels permeability can participate in neuroprotection strategies.

This thesis is broken into four chapters. The first two chapters summarize two separate lines of investigation into the role of a putative neurotoxin in the pathogenesis of Huntington's Disease (HD). The third chapter outlines an investigation of the putative role of beta-N-methylamino-L-alanine (BMAA) in the pathogenesis of amyotrophic lateral sclerosis (ALS), while the final chapter details a post-mortem investigation of the contents of biogenic amines and amino acids in the brain of a man who died of a familial form of parkinsonism. Chapter I is a description of a chromatographic technique developed to isolate quinolinic acid (QA), an endogenous compound implicated in the pathogenesis of HD, from deproteinized human sera. A cation exchange column was used to selectively isolate QA, which was eluted with 10 mM HCl. The eluted fractions were analyzed by UV spectrometry to isolate and quantify QA. Once the fractions corresponding the elution of authentic QA were isolated, concentrated and the excess HCl removed, the fractions were added to growing fetal rat striatal explant cultures as an assay of neurotoxicity. Since HD involves the selective degeneration of GABAergic neurons in the striatum, the activity of glutamic acid decarboxylase, the final enzyme in the synthesis of GABA, was used to determine the viability of the cultures. Unfortunately, the method was confounded by the contamination of all effluents by compounds originating from the cation exchange resin, which were discovered to be neurotoxic to the striatal cultures, and as a result the investigation had to be abandoned. Chapter II describes an investigation designed to further characterize the nature of neurotoxicity observed in the sera obtained from patients with HD (Perry et al. 1987). Compounds with the capacity to selectively stimulate neurons at the N-methyl-D-aspartate (NMDA) receptor have been implicated in a variety of neurodegenerative disorders, including HD. Selective antagonists at the NMDA receptor have been shown to protect neurons from the degenerative effects of such "excitotoxins". The investigation described used MK-801, a potent noncompetitive NMDA antagonist, in an attempt to protect fetal rat striatal cultures from the neurodegenerative effects of the sera obtained from HD patients. The results obtained were equivocal. No evidence was obtained to support a role of the NMDA receptor in the mediation of the neurotoxicity, and in addition the neurodegenerative effects of HD sera were not reproduced in the present investigation. A variety of possible explanations for the apparent discrepancy are suggested. Chapter III describes an experiment intended to produce an animal model of ALS based on the observations by Spencer et al. 1987 that chronic oral administration of BMAA in monkeys produced the histological and behavioural characteristics of this disease. In the present investigation synthetic D,L-BMAA was given by gavage to mice over an eleven week period. Since BMAA is known to act at the NMDA receptor, a subset of the mice were also given MK-801 in an effort to protect them from any deleterious effects based on the action of BMAA at this receptor. The animals were sacrificed at the end of the experiment, and biochemical analyses were performed on the striata and cortices of the animals. In addition, neuropathological studies were performed on the spinal cords, basal ganglia and related structures. The results indicated no biochemical or neuropathological abnormality as a result of BMAA administration. Chapter IV describes a post-mortem investigation of a man who was a member of a well described pedigree which carries an autosomal dominant form of parkinsonism. The object of the investigation was to determine post-mortem levels of dopamine, noradrenaline, serotonin and their metabolites, in addition to amino acids in various regions of brain. Although conflicting evidence was obtained during life, neuropathological findings and the present neurochemical analyses confirm the degeneration of the nigrostriatal dopaminergic tract, characteristic of parkinsonism, in this man. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

Neurons comprise the main information processing cells of the nervous system. To integrate and transmit information, neurons elaborate dendritic structures to receive input and axons to relay that information to other cells. Due to their intricate structures, dendrites and axons are susceptible to damage whether by physical means or via disease mechanisms. Studying responses to axon injury, called Wallerian degeneration, in the neuronal processes of Drosophila melanogaster has allowed the identification of genes that are required for injury responses. Screens in Drosophila have identified dsarm and highwire as two genes required for axon degeneration; when these genes are mutated axons fail to degenerate after injury, even when completely cut off from the neuronal cell body. We found that these genes are also required for dendrite degeneration after injury in vivo. Further, we reveal differences between axon and dendrite injury responses using in vivo timelapse recordings and GCaMP indicators of intracellular and mitochondrial calcium transients. These data provide insights into the neuronal responses to injury, and better define novel targets for the treatment of neurodegenerative diseases.