Traumatic brain injury (TBI) is a serious problem facing the medical community. Every year, over 1.7 million TBIs occur in the United States alone (CDC, 2010). Over 25 years of research and 21 major clinical trials have failed to yield a pharmaceutical treatment for this complicated injury (Maas et al., 2007). One of the possible reasons for the many clinical failures is a lack of behavioral assessment at the level of animal models. In particular, there is typically only one type of cognitive measure employed in most studies, usually a measure of spatial learning (e.g. Morris water maze). In other fields, alternative measures have been utilized for many years, including non-spatial discriminations. The primary goal of this study was to evaluate the use of a visual discrimination in a model of frontal TBI and determine whether or not administering a neuroprotectant could alleviate deficits in discrimination. Long-Evans rats were trained on a simple visual discrimination task and a progressive ratio schedule of reinforcement (PR). After assessing their baseline discrimination performance, motor ability and PR performance, they were advanced to surgery and given either a bilateral frontal controlled cortical impact TBI or sham procedure. Following TBI, injured rats were given either doses of the neuroprotectant nicotinamide (NAM; 150 mg/kg, i.p.) or a saline solution (1 ml/kg, i.p.). They were then assessed for 35 days on the discrimination and progressive ratio. On days 7, 14 and 27, motor abilities were assessed in automated motor activity monitors. On days 15-18 and 21-23 post-surgery, rats were also assessed on the Morris water maze (MWM). On day 43 post-surgery, rats were transcardially perfused and brains extracted. Brains were briefly post-fixed and then sliced on a sliding microtome at 40 µm. These slices were then mounted to slides and stained with cresyl violet to examine the extent of the lesion. Brain injury impaired performance on the discrimination task and PR task. In the discrimination task, deficits were primarily driven by an inability to complete chains of responses. On the PR task, deficits were characterized by reduced break points and low rates of responding. Administration of NAM reduced deficits in discrimination and PR performance. There were no gross motor deficits as a result of the injury. On the MWM task and measures of lesion size, there were no improvements due to NAM administration. Based on the outcome of this study, operant measures such as discrimination or progressive ratio could be incorporated into the testing battery for experimental TBI. Despite some of the challenges of adapting tasks designed for single-subject analysis, it is well worth the time spent due to the robust ability to detect deficits. Additionally, this study showed that nicotinamide administration was neuroprotective across multiple tasks, suggesting that these tasks are indeed well suited for the assessment of pharmacological agents and that nicotinamide has treatment potential for clinical populations.

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The global occurrence of metabolic syndrome has reached epidemic proportions and is a contributing factor in the rising incidence of cognitive decline in the aging population. While pre-clinical research has advanced our understanding of many of the mechanisms underlying metabolic syndrome, animal models often do not reflect the complexity of human disease. For example, animal models that investigate the role played by diet in metabolic syndrome have generally focused on a single macronutrient, in particular fat or carbohydrate. As a result, although a balanced diet and increased physical activity are commonly recommended to treat metabolic syndrome symptomatology, their long-term cerebrovascular benefits are uncertain. To address these gaps in knowledge, a “Cafeteria” diet consisting of 16 common ultra-processed grocery store food items was used to model human metabolic syndrome in the rat. I compared rats fed a Cafeteria diet (CAF) to those fed “standard” chow (SD) as well as to a third group that underwent a switch to chow after chronic exposure to the Cafeteria diet (SWT). In a first study, I showed that three months of exposure to the Cafeteria diet produced metabolic syndrome as well as hippocampal neuroinflammation with increased microglial proliferation. These were fully reversed in SWT rats. Nonetheless, the Cafeteria diet did not worsen spatial learning and memory performance as assessed using the Barnes maze. In a second study, brain perfusion was examined using continuous arterial spin labeling magnetic resonance imaging (CASL MRI). Cortical and hippocampal resting perfusion was increased in CAF rats while cerebrovascular reactivity in response to a 10% CO2 vasodilatory challenge was reduced. Furthermore, while resting perfusion improved in SWT rats, cerebrovascular reactivity remained impaired. These cerebral blood flow outcomes were not accompanied by alterations in microvascular architecture or integrity as determined by rat endothelial cell antigen-1 (RECA-1) and immunoglobulin G (IgG) histology. Taken together, these results demonstrate that the Cafeteria diet is an effective model of metabolic syndrome that negatively impacts brain hemodynamic function. Moreover, while a dietary lifestyle intervention can recover peripheral features of metabolic syndrome, neuroinflammation, and resting perfusion, it is insufficient to completely reverse deficits in cerebrovascular reactivity. These findings are compelling as they speak to the detrimental effects of ultra-processed food consumption on cerebrovascular reserve capacity, believed to be an important factor in cognitive decline.

Orientador: Iscia Teresinha Lopes-Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-16T21:43:20Z (GMT). No. of bitstreams: 1 Pascoal_ViniciusD'AvilaBitencourt_D.pdf: 6752850 bytes, checksum: 4a1854e85492962b7451dd4fceef2360 (MD5) Previous issue date: 2010 / Resumo: As epilepsias afetam aproximadamente 2% da população mundial. Dentre as diferentes síndromes epilépticas descritas, a epilepsia de lobo temporal (ELT) é a mais freqüente, representando 40% dos casos, os quais são frequentemente refratários ao tratamento clínico. Uma das ferramentas mais utilizadas para tentar compreender a fisiopatologia da ELT são modelos experimentais, os quais apresentam epileptogenicidade similar àquela observada em tecidos "epilépticos" humanos quando estudados ex vivo. Dentre os vários modelos disponíveis, aquele induzido pela pilocarpina, além de muito bem estabelecido em nosso meio, tem ampla caracterização molecular, histológica, fisiológica e fenomenológica. Estudos moleculares prévios nesse modelo experimental já demonstraram o aumento da expressão de vários genes durante a fase aguda (fase de estado de mal epiléptico), porém, permanece ainda obscuro, quais desses genes e/ou vias de sinalização poderiam ser críticos para a determinação das lesões (morte celular em regiões hipocampais específicas determinando a chamada esclerose mesial temporal) e responsáveis pela epileptogênese na fase crônica do modelo (crises parciais complexas espontâneas). Baseando-nos nesses achados prévios propomos investigar diretamente o papel do gene interleucina 1- b (Il1b), o qual tem a putativa função de aumentar a liberação de glutamato durante a fase aguda do modelo da pilocarpina. Nossa estratégia experimental foi baseada no silenciamento pós-transcricional pela técnica de interferência por RNA (RNAi) aplicada "in vivo". Nossos resultados indicam que o gene Il1b tem um papel relevante no controle da homeostase no SNC, pela alteração da atividade e expressão de fatores de transcrição, com 22 impacto na expressão de recaptadores de glutamato e na taxa de mortalidade dos animais pós status epilepticus (SE). Além disso, o silenciamento do gene Il1rn, foi capaz de diminuir a morte neuronal nas regiões CA1, CA3 e giro denteado do hipocampo, como observado no material obtido dos animais na fase crônica. No entanto, apesar das ações da Il1b que observamos na fase aguda, o aumento da sua ação pelo silenciamento do Il1rn, não foi capaz de alterar a ocorrência de crises crônicas recorrentes ou a reorganização sináptica (sprouting) observados na fase crônica. Portanto, nossos resultados demonstram que a alteração na expressão do gene Il1b foi capaz de mudar a resposta fenotípica dos animais na fase aguda e teve um impacto na redução da morte neuronal em regiões críticas do hipocampo na fase crônica, porém não parece ter um papel crítico na determinação da epileptogênese na fase crônica. Além disso, nosso trabalho demonstrou a viabilidade do uso da RNAi na investigação funcional de genes envolvidos na patogênese das epilepsias in vivo / Abstract: The epilepsies affect approximately 2% of the world population; among the different epilepsy syndromes temporal lobe epilepsy (TLE) is one of the most frequent, representing 40% of all patients, who are often refractory to medical treatment. One of the strategies used to understand the pathophysiology of TLE are experimental animal models, which have a similar epileptogenicity as compared to human 'epileptic' tissues studied ex vivo. Among the several animal models available, the pilocarpine induced model is very well established and it has extensive molecular characterization, as well as histological, physiological and phenomenological studies. Previous molecular studies in this experimental model hás demonstrated an increased expression of several different genes during the acute phase (status epilepticus); however, it remains unclear, which one of these genes and / or signaling pathways could be critical in determining cell death leading to mesial temporal sclerosis, which is responsible for the epileptogenesis in the chronic phase of the model (spontaneous complex partial seizures). Based on these previous findings we propose to directly investigate the role of Il1b, which could be involved in the increased release of glutamate during the acute phase of the pilocarpine model. Our experimental strategy was based on the post-transcriptional gene silencing by the technique of RNA interference (iRNA) applied in vivo. Our results indicate that the Il1b gene has an important role in controlling homeostasis in the CNS by modulating the activity and expression of transcription factors which appear to interfere with glutamate reuptake. In addition, we observed a phenotypic impact of Il1b gene silencing in the mortality rate of animals after status epilepticus (SE). 24 However, despite the effect of Il1b observed in the acute phase, the modulation of its expression by RNAi was not sufficient to change the frequency of recurrent seizure or synaptic reorganization observed in chronic phase. In addition, silencing Il1rn was able to decreased cell death in CA1, CA3 and dentate gyrus as observed in material obtained form animals in the chronic phase. However, in spite of the effect of Il1b in the acute phase, its increased expression by means of silencing of Il1rn was not able to change the occurrence of habitual seizures or synaptic reorganization, sprouting in the chronic phase. Therefore, our results demonstrate that changes in Il1b gene expression were able to impact the phenotype of the animals in the acute phase, as well as to reduce cell death in critical hippocampus regions in the chronic phase. However, it seems not to have a critical role in the epileptogenic process in the chronic phase. Furthermore, our study demonstrated the feasibility of using RNAi as a tool for functional studies of epileptogenesis in vivo / Doutorado / Neurociencias / Doutor em Fisiopatologia Medica

In this thesis I used Caenorhabitis elegans as a model of Fetal Alcohol Spectrum Disorder (FASD) to study the physical and behavioral effects of ethanol exposure during embryonic development. Davis et al. (2008) found that ethanol exposure during larval development in C. elegans produced physical/developmental and behavioral effects; however, whether exposure during embryonic development might produce similar outcomes remained to be elucidated. Because the type and degree of effects caused by developmental ethanol exposure was dependent on the pattern of ethanol treatment, in the first part of the thesis I investigated the physical/developmental effects of embryonic exposure to various ethanol doses, exposure durations, onsets and frequencies. I found that exposure to >30% ethanol for an hour during embryonic development was necessary to lower hatch rate, delay reproductive onset, and reduce body size in C. elegans. Furthermore, exposure during early embryonic development caused a larger effect than exposure during later stages, and multiple exposures produced a worse outcome than a single exposure for a comparable duration. In the second part of the thesis, I investigated locomotory activities and habituation of adult C. elegans exposed to various patterns of embryonic ethanol treatment. I found that the rate of locomotion was altered differently by chronic and acute embryonic ethanol exposure, but I did not find any effect in short- or long-term habituation. In summary, I have characterized the pattern of embryonic ethanol exposure necessary to produce physical/developmental effects in C. elegans, and identified the types of exposure conditions that would cause worse outcomes than others; in addition, I have found that embryonic ethanol exposure affects the rate of locomotion in C. elegans. In this thesis, I have established a foundation for the future investigation into the physical and motor defects caused by embryonic ethanol exposure in C. elegans. / Medicine, Faculty of / Graduate

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22001号 / 医博第4515号 / 新制||医||1038(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 井上 治久, 教授 林 康紀, 教授 高橋 淳 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23071号 / 医博第4698号 / 新制||医||1049(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 伊達 洋至, 教授 YOUSSEFIAN Shohab, 教授 平井 豊博 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23371号 / 医博第4740号 / 新制||医||1051(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 髙橋 良輔, 教授 安達 泰治, 教授 YOUSSEFIAN Shohab / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Rationale and objectives: Because of known and imputed roles of dopaminergic and nicotinic cholinergic systems in a variety of neurological and neuropsychiatric disorders, combined neurochemical and behavioral methods assessments were made to study the intermodulatory roles of these neurochemical systems. Methods: Rats were treated daily during postnatal ontogeny with the dopamine D2/D3 agonist, quinpirole (QNP) HCl (1.0 mg/kg/day), for the first 3 weeks from birth. This priming process replicated previous findings of behavioral sensitization, manifested as hyperlocomotion, increased paw treading with jumping, and increased yawning. Results: All effects were partially or totally blocked by acute treatment with nicotine (0.3 mg/kg, i.p.). The effects of nicotine, in turn, were partially or totally blocked by the nicotinic antagonist, mecamylamine (1.0 mg/kg, i.p.). In concert with these behavioral actions, QNP-primed rats displayed greater binding of [3H]cytisine in midbrain and cerebellum and greater [125I]α- bungarotoxin binding in hippocampus and striatum. Conclusions: Accordingly, these selective ligands for α4β2 and α7 nicotinic receptors, respectively, demonstrate that nicotinic receptors are altered by dopamine D2/D3 agonist treatment of rats with primed dopamine receptors. We propose that nicotinic agonists may have a therapeutic benefit in behavioral disorders brought about by central dopaminergic imbalance.

Adolescence is a transitional period between childhood and adulthood, in which the individual undergoes significant cognitive, behavioral, physical, emotional, and social developmental changes. During this period, adolescents engage in experimentation and risky behaviors such as licit and illicit drug use. Adolescents' high vulnerability to abuse drugs and natural reinforcers leads to greater risk for developing substance use disorders (SUDs) during adulthood. Accumulating evidence indicates that the use and abuse of licit and illicit drugs during adolescence and emerging adulthood can disrupt the cholinergic system and its processes. This review will focus on the effects of peri-adolescent nicotine and/or alcohol use, or exposure, on the cholinergic system during adulthood from preclinical and clinical studies. This review further explores potential cholinergic agents and pharmacological manipulations to counteract peri-adolescent nicotine and/or alcohol abuse.