The sigma-1 receptor (sig-1R) is a unique endoplasmic reticulum (ER) chaperone protein that interacts with a variety of voltage- and ligand-gated ion channels, which are components of an intricate system that regulates neuronal functioning. While there is an extensive body of knowledge pertaining to the sig-1R, many questions remain. The first question this thesis addresses is how the sig-1R modulates the functioning of the N-methyl-D-aspartate receptor (NMDAR). Using a heterologous expression system, I provide evidence that the mechanism of modulation is likely not a direct interaction between sig-1R and NMDAR and that this is not affected by the presence or absence of the membrane-associated guanylate kinases (MAGUK) protein PSD-95. The next question addressed investigates the impact of sig-1R absence on the synaptic physiology and action potential firing of CA1 pyramidal neurons. It was found that there is not a significant difference in these parameters, suggesting a non-essential role of the sig- 1R under normal physiological conditions. The third topic covered in my studies explores the sig-1R KO mouse in the Aβ25-35 infusion model of Alzheimer’s disease (AD). Preliminary results suggest that there is a dysfunction in the action potential characteristics and after- hyperpolarization characteristics of challenged sig-1R KO mice. Overall my results provide the groundwork for future experiments that will lead to a better understanding of the sig-1R and its role in cellular and synaptic physiology.

Substance use disorders are a prominent issue within the United States that must be addressed given the high prevalence, economic cost, and negative health consequences of these medical conditions. Current treatments are inadequate due to the limited success of behavioral therapies and the lack of pharmacological interventions geared towards preventing the neuroplastic changes initiated by substances of abuse that lead to addiction. Sigma-1 receptors represent promising pharmacological targets for treatment of substance use disorders involving cocaine and methamphetamine use. A review of recent studies suggests that sigma-1 receptors contribute to the underlying mechanisms of action utilized by cocaine. Yet the use of sigma-1 receptor antagonists shows promising results of mitigating the physiological effects induced by cocaine. In contrast to cocaine, sigma-1 receptors have yet to be linked to the underlying mechanisms of action utilized by methamphetamine. However studies indicate that the use of sigma-1 receptors agonists creates a neuroprotective effect against the physiological effects induced by methamphetamine. Currently the pharmacological targeting of sigma-1 receptors is not utilized to treat substance use disorders. A review of literature was conducted in order to elucidate the mechanistic role that sigma-1 receptors play in mediating the physiological effects induced by cocaine and methamphetamine that lead to addiction. Using this information, the potential use of sigma-1 receptors as therapeutic targets was discussed in order to provide insight about the benefits and limitations of utilizing such an intervention as treatment for substance use disorders involving cocaine and methamphetamine use.

La maladie d'Alzheimer est la démence neurodégénérative la plus fréquente, en particulier chez les personnes âgées. A l'heure actuelle, aucun traitement ne permet d'arrêter efficacement le développement de la maladie. Le tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine (ANAVEX2-73) est un composé mixte avec une affinité modérée, de l'ordre du µM pour les récepteurs muscariniques et les récepteurs sigma-1. Des données préliminaires ont montré que la molécule avait des propriétés anti-amnésiantes et neuroprotectrices dans un modèle non transgénique de la maladie d'Alzheimer. L'objectif de cette thèse est de poursuivre le développement préclinique de la molécule. Nous avons montré, d'abord dans un modèle non-transgénique de la maladie d'Alzheimer, le modèle d'injection de peptide AB(25-35) oligomérisé chez la souris, que la molécule prévient l'hyperphosphorylation de la protéine Tau ainsi que la production du peptide AB(1-42), deux éléments clés de la physiopathologie de la maladie. Nous avons utilisé ce même modèle pour montrer que l'ANAVEX2-73 prévient les déficits de la fonction mitochondriale, qui sont présents de manière constante et précoce chez les patients. Enfin, nous avons montré qu'un traitement chronique de deux mois avec le composé, dans un modèle de souris transgéniques de la maladie, permet de restaurer les capacités cognitives chez les souris, de diminuer le stress oxydant et d'augmenter les marqueurs synaptiques. Cependant le traitement n'a pas permis de réduire la charge amyloïde dans le cerveau des souris. L'ensemble de ces résultats est encourageant pour le développement futur de la molécule, puisque cette dernière, en plus d'être neuroprotectrice et anti-amnésiante semble être efficace sur les éléments clés de la physiopathologie de la maladie. / Alzheimer's disease is the most common form of dementia in the elderly. There is however no efficient treatment to stop the disease progression. Tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmetanamine (ANAVEX2-73) is a mixed compound with moderate affinity for muscarinic and sigma-1 receptors. Preliminary data showed ANAVEX2-73 had anti-amnesic and neuroprotective poperties, in a non-transgenic model of Alzheimer's disease. The aim of this thesis is to improve knowledge about preclinical data of this molecule. We first showed that, in the non-transgenic AB(25-35) mouse model, ANAVEX2-73 prevented Tau protein hyperphosphorylation and AB(1-42) peptide seeding, two key parameters involved in Alzheimer's disease physiopathology. We also used this model tho show that ANAVEX2-73 prevented mitochondrial dysfunction, consistently reported as an early event of the disease in patients. The last part of this thesis showed that a two-month chronic treatment with ANAVEX2-73 in a transgenic mouse model of Alzheimer's disease reversed cognitive dysfunction and prevented loss of synaptic markers and increased of oxidative stress. However, we could not show a decrease of amyloid load in mouse brain after chronic treatment. Altogether, these results suggest that ANAVEX2-73 treatment could be effective to treat Alzheimer's disease. In addition to its neuroprotective and anti-amnesic property, it also prevents key hallmarks involved in the physiopathology of Alzheimer's disease.

A dor neuropática atinge cerca de 6 a 10% da população global e estima-se o seu aumento nos próximos anos. Essa síndrome não tem cura e afeta consideravelmente a qualidade de vida das pessoas por ela acometidas. Os medicamentos utilizados atualmente para o seu tratamento, como antidepressivos, anticonvulsivantes, opióides, dentre outros, não proporcionam um resultado satisfatório pelo fato de não reduzirem consideravelmente os sintomas e/ou por terem muitos efeitos colaterais. Pesquisas recentes mostram que o receptor sigma-1 pode ser utilizado no tratamento da dor neuropática. Verificou-se na literatura uma nova série de pirimidinas que são capazes de se ligar ao receptor sigma-1, atuando como seus antagonistas, sendo potenciais alvos para a produção de fármacos que podem ser utilizados no tratamento da dor neuropática. Então, estudos de Relações Quantitativas Estrutura-Atividade (QSAR) foram realizados utilizando os métodos de Mínimos Quadrados Parciais (PLS) e Redes Neurais Artificiais (ANN) para prever a atividade biológica dessa série de pirimidinas. Os resultados obtidos se mostraram satisfatórios tanto para o método de PLS (r2 = 0,877, q2 = 0,800 e r2teste = 0,738), quanto para o método de ANN (r2trein = 0,734, r2val = 0,753 e r2teste = 0,676), mostrando que o conjunto de compostos antagonistas do receptor Sigma-1 pode ser descrito tanto de forma linear quanto de forma não-linear. / Neuropathic pain affects about 6 to 10% of the global population and it is estimated to increase in the coming years. This syndrome has no cure and considerably affects the life quality of people affected by it. Medications currently used for its treatment, such as antidepressants, anticonvulsants, opioids, among others, do not provide a satisfactory result because they do not significantly reduce the symptoms and/or have many side effects. Recent research shows that the sigma-1 receptor can be used in the treatment of the neuropathic pain. A new series of pyrimidines have been found in the literature, which are capable of binding to the sigma-1 receptor, acting as its antagonists, and have been synthesized as potential targets that can be used in the treatment of the neuropathic pain. Therefore, Quantitative Structure-Activity Relationships (QSAR) were performed using Partial Least Squares (PLS) and Artificial Neural Networks (ANN) methods to predict the biological activity of this series of pyrimidines. Through the mathematical models obtained by PLS (r2 = 0.877, q2 = 0.800 and r2test = 0.738) and ANN (r2trein = 0.734, r2val = 0.753 and r2test = 0.676) methods, it was showed that they were able to predict the biological activity of the studied pyrimidines.

A dor neuropática atinge cerca de 6 a 10% da população global e estima-se o seu aumento nos próximos anos. Essa síndrome não tem cura e afeta consideravelmente a qualidade de vida das pessoas por ela acometidas. Os medicamentos utilizados atualmente para o seu tratamento, como antidepressivos, anticonvulsivantes, opióides, dentre outros, não proporcionam um resultado satisfatório pelo fato de não reduzirem consideravelmente os sintomas e/ou por terem muitos efeitos colaterais. Pesquisas recentes mostram que o receptor sigma-1 pode ser utilizado no tratamento da dor neuropática. Verificou-se na literatura uma nova série de pirimidinas que são capazes de se ligar ao receptor sigma-1, atuando como seus antagonistas, sendo potenciais alvos para a produção de fármacos que podem ser utilizados no tratamento da dor neuropática. Então, estudos de Relações Quantitativas Estrutura-Atividade (QSAR) foram realizados utilizando os métodos de Mínimos Quadrados Parciais (PLS) e Redes Neurais Artificiais (ANN) para prever a atividade biológica dessa série de pirimidinas. Os resultados obtidos se mostraram satisfatórios tanto para o método de PLS (r2 = 0,877, q2 = 0,800 e r2teste = 0,738), quanto para o método de ANN (r2trein = 0,734, r2val = 0,753 e r2teste = 0,676), mostrando que o conjunto de compostos antagonistas do receptor Sigma-1 pode ser descrito tanto de forma linear quanto de forma não-linear. / Neuropathic pain affects about 6 to 10% of the global population and it is estimated to increase in the coming years. This syndrome has no cure and considerably affects the life quality of people affected by it. Medications currently used for its treatment, such as antidepressants, anticonvulsants, opioids, among others, do not provide a satisfactory result because they do not significantly reduce the symptoms and/or have many side effects. Recent research shows that the sigma-1 receptor can be used in the treatment of the neuropathic pain. A new series of pyrimidines have been found in the literature, which are capable of binding to the sigma-1 receptor, acting as its antagonists, and have been synthesized as potential targets that can be used in the treatment of the neuropathic pain. Therefore, Quantitative Structure-Activity Relationships (QSAR) were performed using Partial Least Squares (PLS) and Artificial Neural Networks (ANN) methods to predict the biological activity of this series of pyrimidines. Through the mathematical models obtained by PLS (r2 = 0.877, q2 = 0.800 and r2test = 0.738) and ANN (r2trein = 0.734, r2val = 0.753 and r2test = 0.676) methods, it was showed that they were able to predict the biological activity of the studied pyrimidines.

Glioblastoma multiforme (GBM) is the most devastating primary brain tumour characterised by infiltrative growth and resistance to therapies. According to recent research, the sigma-1 receptor (sig1R), an endoplasmic reticulum chaperone protein, is involved in signaling pathways assumed to control the proliferation of cancer cells and thus could serve as candidate for molecular characterisation of GBM. To test this hypothesis, we used the clinically applied sig1R-ligand (S)-(−)-[18F]fluspidine in imaging studies in an orthotopic mouse model of GBM (U87-MG) as well as in human GBM tissue. A tumour-specific overexpression of sig1R in the U87-MG model was revealed in vitro by autoradiography. The binding parameters demonstrated target-selective binding according to identical KD values in the tumour area and the contralateral side, but a higher density of sig1R in the tumour. Different kinetic profiles were observed in both areas, with a slower washout in the tumour tissue compared to the contralateral side. The translational relevance of sig1R imaging in oncology is reflected by the autoradiographic detection of tumour-specific expression of sig1R in samples obtained from patients with glioblastoma. Thus, the herein presented data support further research on sig1R in neuro-oncology.