Thesis (M. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 40-50). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 110-116). Also available in electronic format on the Internet.

Thesis (M. Sc.)--Carleton University, 2008. / Includes bibliographical references (p. 71-81). Also available in electronic format on the Internet.

Thesis (M.SC.) - Carleton University, 2007. / Includes bibliographical references (p. 69-75). Also available in electronic format on the Internet.

Thesis (M. SC.)--Carleton University, 2001. / Includes bibliographical references (p. 35-53). Also available in electronic format on the Internet.

Made available in DSpace on 2015-07-22T20:50:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Trinomys yonenagae (TY) é um roedor fossorial das dunas da Caatinga, pertencente à família Echimydae e conhecido localmente como rabo de facho. A observação de que alguns indivíduos dessa espécie animal apresentam crises convulsivas espontâneas estimulou-nos ao estudo de algumas características de seu sistema nervoso que pudessem estar subjacentes a este quadro. Através de técnicas de eletrofisiologia in vitro, com a utilização de protocolos de indução de hiperexcitabilidade e de estudo da potenciação a longo prazo, procuramos identificar o padrão eletrofisiológico da circuitaria hipocampal do TY e compará-lo ao de ratos Wistar. Adicionalmente, procuramos também verificar como animais da espécie TY se comportam em relação a dois modelos clássicos de indução de epilepsia: método do abrasamento amigdaliano e aplicação sistêmica de pilocarpina. No protocolo de potássio alto, observamos em TY uma maior sensibilidade ao aumento gradual de potássio no líquido cefalorraquiano artificial (LCRa). No protocolo de adição de antagonista do receptor GABAA (bicuculina) no LCRa, não observamos quaisquer diferenças significativas nos registros extracelulares entre TY e Wistar. No protocolo da ausência de magnésio no LCRa, ambas as espécies apresentaram atividade epileptiforme espontânea, e quando submetidas a estimulação elétrica, as respostas em ambas as espécies não diferiram estatisticamente. No estudo da potenciação a longo prazo, observamos que, embora as médias dos declives normalizados em TY terem se apresentado sempre inferiores às de Wistar após o estímulo de alta frequência, estes valores entre as duas espécies não diferiram estatisticamente. Os dados eletrencefalográficos e comportamentais foram similares entre TY e Wistar nos dois modelos de indução de epilepsia, com exceção da dose de pilocarpina utilizada para elicitar o status epilepticus em TY, que foi menor. A caracterização eletrofisiológica e os resultados obtidos mediante os modelos de epilepsia são contribuições interessantes para o conhecimento do sistema nervoso do TY e revelam a importância para futuros trabalhos nesta espécie para aquisição de novos conhecimentos que podem estar envolvidos na gênese das crises convulsivas. / Trinomys yonenagae (TY) is a fossorial rodent dweller of sand dunes of the Caatinga, pertaining to Echimydae family and known locally as rabo de facho. The observation of some animals of this species show spontaneous seizures stimulated us the study of some characteristics of its nervous system that could to be subjacents to this condition. Through techniques of eletrophysiology in vitro, with the utilization of protocols of induction of hiperexcitability and study of the long-term potentiation (LTP), we aimed at to identifying the eletrophysiologic pattern of hippocampal circuitry of the TY and comparing it to Wistar rats. Additionaly, we also aimed at verifying how animals of the TY species behave regarding two classic models of epilepsy induction: amygdala kindling and systemic aplication of pilocarpine. In the high potassium protocol, we observed in TY a higher sensibility to gradual increase of potassium in the artificial cerebrospinal fluid (ACSF). In the protocol of addition of antagonist of GABAA receptor (bicuculine) in the ACSF, we did not observe any significative differences in the extracellular records between TY and Wistar. In the absence magnesium protocol in the ACSF, both species showed spontaneous epileptiform activity, and when both species were submited to electric stimulation, their responses did not differ statisticaly. In the study of LTP, we observed that, although the normalized slopes averages in TY have showed always smaller than of Wistar after high frequence stimulus, these values between the two species did not differ statistically. The electroencephalographic and behavioral data were similar between TY and Wistar in the two epilepsy induction models, with exception of the pilocarpine dosage used to elicite status epilepticus in TY, that was lower. The electrophysiological characterization and the obtained results against the epilepsy models are interesting contributions to the knowledge of the nervous system of the TY and reveal the importance to futures works in this species for the acquisition of new knowledges that can to be involved in the genesis of the seizures. / TEDE / BV UNIFESP: Teses e dissertações

Stress and limbic iritability in depression and alcohol dependency Denisa Jasová Abstract Depressive disorders and alcohol dependency recently present epidemiologically most significant psychiatric disorders. According to current research both diseases are multifactorial, mainly represented by genetic and environmental conditions. Several recent research studies are mainly focused on social factors related to stress and traumatic events such as neglect, deprivation, verbal, emotional, physical and sexual abuse, bullying and others. Important feature of these pathological conditions present disbalance between excitatory and inhibitory systems. In this context in affective disorders as well as in alcohol dependency these inhibitory deficits are represented by increased sensitivity and excitability of the limbic system called limbic irritability. Several studies suggested that these pathological changes may be described using the kindling model that potentially may explain limbic changes similar to temporal lobe epilepsy which may produce affective, cognitive and psychosensory symptoms but without typical changes that occur in neurologically diagnosed epilepsy. Following these findings significant correlations between depression and limbic irritability and between limbic irritability and alcohol craving have...

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O abrasamento à um modelo experimental bem conhecido de epilepsia progressiva, induzida por estimulaÃÃo sublimiar elÃtrica ou quÃmica. Apenas recentemente o abrasamento induzido por nicotina (NIC) foi caracterizado farmacologicamente e histologicamente. AlÃm disso, à sabido que diferenÃas de gÃnero e de idade na susceptibilidade à convulsÃo sÃo uma das questÃes mal resolvidas na epilepsia. Baseado nestes fatos, o presente estudo objetivou investigar a influÃncia do gÃnero e idade nas alteraÃÃes comportamentais e neuroquÃmicas induzidas pelo abrasamento por nicotina em ratos. Ratos Wistar machos e fÃmeas periadolescente (35-37 dias; n=8 por grupo) e adultos (73-75 dias; n=8 por grupo) foram usados. Durante 4 semanas foi realizada a administraÃÃo repetida de NIC 2,0 mg/kg, intraperitonealmente, de segunda à sexta-feira e as convulsÃes avaliadas de acordo com a escala de Racine. Trinta minutos apÃs a Ãltima administraÃÃo de NIC (25 dia), os animais foram eutanasiados, cÃrtex prÃ-frontal (CPF), corpo estriado (CE) e hipocampo (HC) dissecados e homogenatos a 10% preparados com tampÃo fosfato de potÃssio (pH 7,4). Os homogenatos foram usados para avaliar a atividade da SOD, quantificaÃÃo dos nÃveis de GSH, de nitrito/nitrato (como maneira indireta de determinar o Ãxido nÃtrico) e a formaÃÃo de perÃxidos lipÃdicos pela mensuraÃÃo das substÃncias que reagem ao Ãcido tiobarbitÃrico (TBARS). FÃmeas periadolescentes e adultas e machos adultos apresentaram a mesma susceptibilidade ao desenvolvimento do abrasamento quando comparado aos ratos machos periadolescentes, apresentando estÃgio 5 de convulsÃes apÃs 19 dias de tratamento de NIC, enquanto os ratos machos periadolescentes apresentaram estÃgio 5 apenas apÃs 24 dias de administraÃÃo. Com relaÃÃo Ãs mortes as fÃmeas periadolescentes foram mais susceptÃveis aos efeitos tÃxicos da NIC com 75% de mortes neste grupo. Os machos periadolescentes apresentaram um aumento dos nÃveis de GSH no CPF e CE e nenhuma alteraÃÃo na atividade da SOD, conteÃdo de nitrito e peroxidaÃÃo lipÃdica. Ao contrÃrio, os outros grupos diminuÃram os nÃveis de GSH e a atividade da SOD, com dano na membrana detectado pela elevaÃÃo na peroxidaÃÃo lipÃdica em machos adultos e fÃmeas periadolescentes, mas nÃo em fÃmeas adultas. Em conclusÃo, nossos resultados demonstram que o abrasamento induzido por NIC à influenciado pelo gÃnero e idade do animal e que parÃmetros de estresse oxidativo, estÃo relacionados, pelo menos em parte, à susceptibilidade/resistÃncia do animal Ãs convulsÃes induzidas por esta droga. / Kindling is a well-known experimental model of progressive epilepsy induced by electrical or chemical subthreshold stimulation. Only recently nicotine-induced kindling was pharmacologicaly and histologicaly characterized. Furthermore is known sex and age differences in seizure susceptibility are one of the unresolved issues in epilepsy. Based on this, the present study aimed to investigate gender and age influences in behavioral and neurochemical changes nicotine-induced kindling in rats. Male and Female periadolescent (35-37 days old, n= 8/group) and adult (73-75 days old, n=8/group) Wistar rats were used. During 4 weeks, kindling seizures were induced by repeated administration of NIC 2.0 mg/kg, intraperitoneally, from Monday to Friday. Convulsant activity was evaluated according Racine scale. Thirty minutes after the last administration of NIC, animals were euthanized, prefrontal cortex (PFC), striatum (ST) and hippocampus (HC) dissected and homogenates to 10% prepared with potassium phosphate buffer (pH 7.4). Finally, homogenates were used to evaluate Superoxide Dismutase (SOD) activity, levels Glutathione Reduced (GSH) quantifying, nitrite/nitrate levels (as an indirect way to determine nitric oxide) and lipid peroxides formation by measuring the thiobarbituric-acid reacting substances (TBARS). Female periadolescent and adult and male adult presented same susceptibility to kindling development whem compared to male periadolescent, presented stage 5 seizures after 19 days NIC treatment, whereas male periadolescent rats presented stage 5 only after 24 days of administration. Regarding to deaths female periadolescente were more susceptible to toxic effects of NIC with 75% deaths in this group. Male periadolescent presented an increase in the GSH levels in CPF e CE and no change in SOD acitivity, nitrite content and lipid peroxidation. Unlike, other groups decreased GSH levels and SOD activitiy with membrane damage detected by an increase in lipid peroxidation in male adult and female periadolescent, but not in female adult animals. In conclusion, our results demonstrate that NIC-induced kindling is influenced by gender and age and oxidative stress parameters, are related, at least in part, to the animalâs susceptibility/resistance to the kindling induced by this drug.

Stress and limbic iritability in depression and alcohol dependency Denisa Jasová Abstract Depressive disorders and alcohol dependency recently present epidemiologically most significant psychiatric disorders. According to current research both diseases are multifactorial, mainly represented by genetic and environmental conditions. Several recent research studies are mainly focused on social factors related to stress and traumatic events such as neglect, deprivation, verbal, emotional, physical and sexual abuse, bullying and others. Important feature of these pathological conditions present disbalance between excitatory and inhibitory systems. In this context in affective disorders as well as in alcohol dependency these inhibitory deficits are represented by increased sensitivity and excitability of the limbic system called limbic irritability. Several studies suggested that these pathological changes may be described using the kindling model that potentially may explain limbic changes similar to temporal lobe epilepsy which may produce affective, cognitive and psychosensory symptoms but without typical changes that occur in neurologically diagnosed epilepsy. Following these findings significant correlations between depression and limbic irritability and between limbic irritability and alcohol craving have...

Amygdala kindling is commonly used to study the mechanisms involved in epileptogenesis, with long-term amygdala kindling providing a useful model of the behavioural disturbances such as heightened anxiety that can occur between epileptic seizures. The purpose of this thesis was to determine whether increased fear behaviours exhibited by long-term amygdala kindled rats are reflective of previously observed kindling-mediated alterations in the hippocampus. As the hippocampus plays an integral role in contextual learning, the ability of the animals to habituate to a novel environment was evaluated, in order to determine if the rats displayed impairments in this hippocampal-dependent function. In Experiment 1, long-term kindled rats demonstrated consistently elevated exploration and fear over repeated exposure to an initially novel open field, indicating impaired habituation. In Experiment 2, all kindled rats showed elevated exploration and an inability to form a home base in relation to static visual cues, again demonstrating an inability to habituate over repeated exposures to the initially novel environment. Rats that had received 30 or 60 stimulations demonstrated hyperexploratory behaviour and elevated fear, although this behaviour did dissipate to a certain degree by the final day of testing. Long-term kindled rats, having received 99 stimulations, demonstrated extremely heightened fear behaviours that interfered with normal exploration, home base formation and habituation. These fear behaviours included high levels of freezing, disorganized running, and purposive jumping from the open field. Taken together, these results indicate that long-term amygdala kindling does produce deficits in habituation to an initially novel environment. As habituation necessarily involves the hippocampal-dependent roles of contextual learning and memory, the current research suggests that long-term kindling does impair hippocampal function and that this may contribute to kindling-induced fear behaviours. This research may help to understand the mechanisms involved in emotional disturbances experienced by human epileptics.