Multiple Sclerosis (MS) is an autoimmune demyelination disease of the central nervous system (CNS). The traditional immunotherapies so far have not been able to stop the progression of the disease. Galanin (GAL) is an inducible neuropeptide. It has diverse regulatory effects in the nervous. The expression of galanin is induced by the administration of estrogen and is increased during pregnancy in rodents. In women with MS, pregnancy has a protective effect associated with significant remission of MS symptoms during the second and third trimester. In this study, using the cuprizone (CPZ) demyelination model of MS I demonstrated that GAL has a pronounced neuroprotective effect on demyelination and remyelination, with estrogen the protection was further enhanced. Moreover, I also found differential activation of GAL receptors in the demyelination and remyelination processes. These results suggest GAL alone or combined with estrogen might introduce next generation strategies for the treatment of MS.

Multiple Sclerosis (MS) is an autoimmune demyelination disease of the central nervous system (CNS). The traditional immunotherapies so far have not been able to stop the progression of the disease. Galanin (GAL) is an inducible neuropeptide. It has diverse regulatory effects in the nervous. The expression of galanin is induced by the administration of estrogen and is increased during pregnancy in rodents. In women with MS, pregnancy has a protective effect associated with significant remission of MS symptoms during the second and third trimester. In this study, using the cuprizone (CPZ) demyelination model of MS I demonstrated that GAL has a pronounced neuroprotective effect on demyelination and remyelination, with estrogen the protection was further enhanced. Moreover, I also found differential activation of GAL receptors in the demyelination and remyelination processes. These results suggest GAL alone or combined with estrogen might introduce next generation strategies for the treatment of MS.

No description available.

No description available.

No description available.

Central nervous system (CNS) myelination is important for proper nervous system function in vertebrates. In demyelinating diseases such as multiple sclerosis, autoimmune-mediated myelin destruction results in neurological impairment; and although remyelination does occur spontaneously, it is poorly understood and insufficient in humans. Zebrafish (Danio rerio) are known to harbour tremendous regenerative capacity of various CNS tissues; however, there is presently only little knowledge of their myelin repair efficiency. An experimental model of myelin injury in zebrafish would permit study of the mechanisms involved in successful remyelination and could potentially guide the development of novel therapeutic agents for mammalian remyelination. This doctoral thesis describes the characterisation of the novel myelin protein Claudin k in zebrafish, demonstrates the establishment of adult zebrafish as an experimental model for CNS de- and remyelination and explores some mechanisms underlying myelin repair. A variety of myelin markers have previously been investigated in zebrafish, including myelin basic protein and myelin protein zero. However, the use of these is limited by either late developmental expression or presence in compact myelin only. Claudin k is a novel tight junction protein specific to zebrafish CNS and PNS, which can be observed early in development and throughout nervous system regeneration. Utilising specific antibodies and a novel transgenic zebrafish line, in which the claudin k promoter drives the expression of green fluorescent protein in myelinating cells, the studies herein characterise the expression of Claudin k, demonstrate the fidelity of the transgenic construct, and investigate the relationship of Claudin k with established myelin and CNS inflammation markers. Data demonstrate that Claudin k expression closely resembles expression patterns of the endogenous gene, and as such provides a key tool for examining CNS myelination in zebrafish. For the study of de- and remyelination in the zebrafish, the experiments herein describe the use of lysophosphatidylcholine (LPC), a detergent-like myelin toxin, which is used widely in rodent models to demyelinate axons. Its application to the adult zebrafish optic nerve induced focal demyelinating lesions, critically without detectable axonal injury, and permitted the study of time course and efficiency of remyelination. Myelin in the lesion area was reduced as detected by both immunohistochemistry and electron microscopy at 8 days post lesion (dpl), and return of the markers to control levels suggested regeneration by 28 dpl. In addition microglial activation was observed along the optic pathway, which also returned to levels compared to unlesioned control by 28 dpl. In young zebrafish (aged 4-6 months), the myelin thickness of remyelinated fibres showed no difference to the pre-lesion state, which is different to mammals, where the myelin thickness is reduced. However, in old fish (aged 18+ months), remyelinated fibres presented with thinner myelin, suggesting that the regenerative capacity of zebrafish declines with age. While the zebrafish as an experimental system has tremendous benefits, such as potential for drug screens using the transparent larvae, capacity for transgenesis and live imaging, experimental models in zebrafish potentially bear several limitations, in particular their distant relationship to humans. To determine whether zebrafish remyelination involves homologous signalling mechanisms to mammals, demyelinated zebrafish optic nerves were treated with human recombinant Semaphorin 3A, an axonal guidance molecule which is well known to inhibit oligodendrocyte precursor cell (OPC) recruitment and remyelination in mammals. Results demonstrated fewer oligodendroglial cells at 14 dpl and less myelinated fibres at 28 dpl in the optic nerve lesion area compared to control treated animals, supporting the hypothesis that zebrafish remyelination may indeed respond to human signalling molecules. Taken together, the findings in this doctoral thesis suggest that this new experimental zebrafish-based model of CNS remyelination can be added to the suite of current models to better understand the remyelination process and that some signalling mechanisms observed in mammals around myelination and OPC recruitment are likely conserved in the zebrafish. In addition, it could potentially be used to discover novel therapeutic targets that promote myelination in injury.

A method for modeling and simulating neural action potential (AP) propagation along the length of an axon containing a number of Ranvier nodes is proposed in this dissertation. A system identification approach is adopted to represent node of Ranvier (NR) response to current pulse stimulus in the form of transfer function representations for NR excitability. Segments of myelinated internodal (IN) and NR regions are cascaded, representing the remaining downstream axon after a site-of-stimulus introduction of an external current pulse. This cascading network is used to simulate "cable" properties and signal propagation along the length of the axon. This work proposes possible solutions to attenuation losses inherited in the classical myelinated cable models and accounts for neuronal AP velocity as well as introducing signal attenuation and transient delays associated with internodal demyelination. This model could aide as a predictive tool for the diagnosis and analysis of axonal signal integrity associated with demyelination pathology. Possible applications could include functional stimulation control methodologies for axon bundles that may exhibit signal fidelity issues associated with demyelination. It is further proposed that this model may serve as an instructive tool for further development and incorporation of other axon dynamic behaviors such as: relative refractory periods of AP generation, NR AP recovery mechanisms and responses to varied current stimulus input. / by George Jason Morales. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

No description available.

Axonal degeneration is the major cause of disability in progressive multiple sclerosis (MS). It has been shown that in MS and relevant disease models, demyelinated axons harbor an increased number of mitochondria, which is reflected in bigger stationary sites of mitochondria, increased mitochondrial activity and increased transport speed of mitochondria. This axonal response of mitochondria to demyelination (ARMD) is protective, as there is an increase in energy demand due to the redistribution of sodium channels along the axon following demyelination. However, it remains to be determined how this ARMD is mounted and how mitochondrial dynamics are involved. By using in vivo and in vitro systems we are determined to elucidate the transport and fusion dynamics of the ARMD and where these additional mitochondria come from. Using a cerebellar slice culture system with lysolecithin induced demyelination, we show that the increase in mitochondrial occupancy of the axon already occurs at 24 hours after demyelination and plateaus around 3 to 4 days after demyelination. At 24 hours, there was a steep increase in the mitochondrial numbers inside the axon, which is then followed by an increase in mitochondrial size over the following days. All parameters decrease again over the following days, but remain elevated compared to baseline even 12 days after demyelination. To determine the source of these additional mitochondria and to assess the fusion dynamics within the axon, we used a lentivirus expressing a mitochondrial targeted photoconvertible dye (mEOS2) to label mitochondria in Purkinje cells. The mitochondria that are labelled green in the Purkinje cell axons are then photoconverted to red by illuminating the initial part of the axon with a 405-nm laser and imaged over the following 20 minutes to determine the transport and fusion dynamics. This showed an increased number of mitochondria moving from the cell body into the axon, as well as an increase in retrograde transport of mitochondria in the demyelinated compared to the myelinated axons. Furthermore the size of newly transported mitochondria and their speed was increased in the anterograde direction. Furthermore, the fusion rate of newly transported mitochondria with stationary converted mitochondria was increased in the demyelinated axons compared to myelinated control. These changes can also be observed in unmyelinated axons, as well as axons of cerebellar slices of the dysmyelinating shiverer mutant with or without lysolecithin treatment. The manipulation of mitochondrial dynamics after demyelination with the fission inhibitor mdivi-1 and the ATPase inhibitor oligomycin both showed an increasing or decreasing effect on the mitochondrial parameters after demyelination respectively. The effect on the axonal health after demyelination was detrimental with both of these treatments. Increasing mitochondrial biogenesis with pioglitazone increased axonal mitochondrial parameters, as well as ameliorated axonal damage after demyelination with lysolecithin. As the neuronal cell bodies in MS harbour mitochondrial DNA deletions, which affects their physiology, including energy production efficiency, another aim of this thesis was to model this deficiency in vitro. As it was not possible to model these mitochondrial defects in vitro within the experiments of this thesis, the characterization of a mitochondrial mutant in vivo model was done as a contribution to a greater set of experiments performed by other members of the Mahad lab.

Orientador: Doralina Guimarães Brum Souza / Banca: Eduardo Antonio Donadi / Banca: Fernando Coronetti Gomes da Rocha / Resumo: A esclerose múltipla (EM) é a doença inflamatória autoimune mais comum do sistema nervoso central que acomete adultos jovens. É mais frequente no sexo feminino e em população caucasiana. Apresenta pior prognóstico nos homens, nos negros e naqueles com idade de início superior a 40 anos. Na maioria dos casos, manifesta-se na forma de surto-remissão, em que o paciente apresenta piora clínico-neurológica e melhora espontânea e parcial do quadro. Na recorrência dos surtos, há um acúmulo de déficits, ao longo do tempo e estas incapacidades que podem ser registradas através da escala do EDSS (derivado do inlgês Expanded Disability Status Scale), cujos valores compreendem entre 0 a 10, sendo 0 a melhor condição do paciente e 10, o óbito. A etiologia permanece desconhecida, mas há evidências que fatores ambientais e genéticos contribuem para o desenvolvimento da doença.A população brasileira apresenta diferentes graus de miscigenação, resultante de intercruzamento da população europeia, africana e ameríndia, de acordo com as regiões do país. Tendo em vista esta peculiaridade e o fato de a EM ser mais grave nos afro-descendentes, bem como apresentar menor prevalência em população miscigenada, torna-se interessante o estudo do risco étnico e genético desta doença no Brasil. Em estudo prévio pelo mesmo grupo, a contribuição genética da população europeia, africana e ameríndia em pacientes com EM foi estimada utilizando um painel de 12 genes marcadores informativos de ancestralidade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Multiple sclerosis (MS) is the most common autoimmune inflammatory disease of the central nervous system that affects young people. It is common in females and in Caucasians, with a ratio of worse prognosis in men, blacks and age of onset more than 40 years. In most patients manifests itself in the form of relapsing-remitting in which the patient presents worsening clinical and neurological and spontaneous and partial improvement of symptoms. In most recurrence of symptoms, there is an accumulation of deficits over time and these impairments are recorded by the EDSS(Expanded Disability Status Scale), whose values comprise between 0 to 10, with 0 the better the patient's condition and 10, death. There is interaction between environmental and genetic factors, but the etiology remains unknown. The Brazilian population is five centuries of crossbreeding between populations. European, African and Amerindian and may have different degrees of miscegenation, according to the regions. In view of this peculiarity and the fact that MS is more severe in Afrodescendants, it is interesting the study of ethno-genetic risk of this disease in Brazil. And for that, the ancestry informative markers (AIMs) will be used as a robust tool in the study of case-control in order to avoid spurious association. They are markers of specific population- and has different frequencies in different populations. To estimate the genetic contribution of each population, in the Brazilian population, one AIMs panel of 12 genes was analyzed. The main genes used to estimate the European contribution will FY, SB19.3 and APOA1. As for the Amerindian be PV92 and CKM. And lastly, for the African, AT3, LPL and MID575. These markers will be analyzed in terms of the biological role, and not for your paper ancestry marker alone. Given this context, we will study the frequency of AIMs individually and... (Complete abstract electronic access below) / Mestre