Asthma is a chronic respiratory disease with a high prevalence in Western countries, including Canada, and increased exacerbations have been associated with ambient air pollution. The maintenance of airways tone is critically dependent on the endogenous bronchodilator, nitric oxide (NO). The nitric oxide synthase (NOS) isoenzymes produce NO from the amino acid, L-arginine, and competition for substrate with the arginase isoenzymes can limit NO production. Imbalances between these pathways have been implicated in the airways hyperresponsiveness (AHR) of asthma. The overall objective of this work was to determine whether arginase and downstream polyamine metabolites are functionally involved in airways responsiveness in animal models of asthma and the adverse responses of allergic animals to air pollution. To this purpose, the expression profiles of proteins involved in L-arginine metabolism were determined in lung tissues from human asthmatics and murine models of ovalbumin (OVA)-induced airways inflammation. Expression of arginase 1 was increased in human asthma and animal models. Competitive inhibition of arginase attenuated AHR in vivo. The roles of the downstream metabolites of arginase, the polyamines (putrescine, spermidine and spermine) were examined by administering them via inhalation to anaesthetized mice. It was demonstrated that spermine increases methacholine responsiveness in normal and allergic mice. Additionally, inhibition of polyamine synthesis improved AHR in a murine model. Thus, arginase and downstream polyamine metabolites contribute to AHR in asthma. Finally, the potential role of arginase in the exacerbation of asthma by air pollution was investigated. For this purpose, murine sub-acute and chronic murine models of allergic airways inflammation were employed, which exhibit inflammatory cell influx and remodeling/AHR, respectively, to determine the role of arginase in the response to concentrated ambient fine particles plus ozone. Allergic mice that were exposed to air pollution exhibited increased arginase activity and expression, compared to filtered air-exposed controls. Furthermore, inhibition of arginase attenuated the air pollution-induced AHR. Thus, the studies of the arginase pathway and downstream metabolites described in this thesis indicate that arginase inhibition may be a therapeutic target in asthma and may also protect susceptible populations against the adverse health effects of air pollution.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neuroinflammation is a neuropathological finding in a number of neurodegenerative diseases. Intraperitoneal injection of lipopolysaccharide (LPS) induces neuroinflammation and memory deficit. Spermine and spermidine are endogenous polyamines that physiologically modulate the N-methyl-D-aspartate (NMDA) receptor in mammals by binding to the polyamine-binding site at the NMDA receptor. Since polyamines improve memory in cognitive tasks, we tested whether the post-training administration of spermine reverses the deficits of memory induced by LPS in the object recognition task in mice. While spermine (1 mg/kg, i.p.) increased, ifenprodil (10 mg/kg, i.p.), a noncompetitive GluN2B-containing NMDA receptor antagonist, decreased the discrimination score on novel object recognition task. Spermine, at dose that did not alter memory (0.3 mg/kg, i.p.), reversed the cognitive impairment induced by LPS (250 μg/kg, i.p.). Ifenprodil (0.3 mg/kg, i.p.) reversed the protective effect of spermine against LPS-induced memory deficits in the novel object recognition task. However, spermine failed to reverse the LPS-induced increased of cortical and hippocampal cytokines levels. The results indicate that spermine protects from LPS-induced memory deficits in mice by mechanisms other than decreasing LPS-induced cytokine production. / A inflamação periférica desencadeia a produção central de citocinas inflamatórias, gerando um quadro de neuroinflamação. Essa condição altera as transmissões no receptor N-Metil-D-Aspartato (NMDA) o que prejudica a memória e a plasticidade sináptica. A injeção de Lipopolissacarídeo (LPS) induz a neuroinflamação e prejudica a memória. A espermina e a espermidina são poliaminas endógenas que modulam fisiologicamente o receptor NMDA em mamíferos. Uma vez que as poliaminas melhoram a memória em tarefas cognitivas, investigamos se a administração pós-treino de espermina reverte o prejuízo de memória induzido por LPS sistêmico na tarefa de reconhecimento de objetos em camundongos. Enquanto a espermina (1 mg/kg, ip) aumentou, o ifenprodil (10 mg/kg, ip), antagonista não competitivo do receptor NMDA contendo GluN2B, diminuiu a discriminação na tarefa de reconhecimento de objetos. A espermina, em doses que não alteram a memória (0,3 mg/kg, ip), reverteu o dano cognitivo induzido por LPS (250 μg/kg, ip). O ifenprodil (0,3 mg/kg, ip) impediu o efeito protetor da espermina contra o prejuízo de memória induzido por LPS na tarefa de reconhecimento de objetos. No entanto, a espermina não reverteu o aumento dos níveis de citocinas pró-inflamatórias induzido por LPS no hipocampo e córtex cerebral. Os resultados do presente estudo indicam que a espermina protege a piora da memória induzida por LPS em camundongos. O mecanismo desta proteção envolve o sítio de ligação das poliaminas no receptor NMDA, e não envolve mecanismos anti-inflamatórios.

Spermine (SPM) is an aliphatic amine which contains four nucleophilic centers and is found in all eukaryotic cells, including nervous cells. It belongs to the group of polyamines, which are molecules associated with both neuroprotection and neurotoxicity. The aim of this study was to investigate the effects of spermine on some parameters of toxicity induced by striatal administration of quinolinic acid (QA), an experimental model of Huntington s disease in adult and male Wistar rats. The intrastriatal administration of QA (180 nmol/site) induced contralateral rotations and increase the number of contralateral body swings. The previous striatal administration of SPM caused mixed effects: at the dose of 0.1 nmol/site increased the number of contralateral rotations; but at 10 nmol/site it reduced both the number of rotations and the contralateral body swings induced by QA. The mechanism by which SPM decreases these motor alterations is probably through its interaction with the NMDA receptor, since the co-administration with arcaine (antagonist of polyamine binding sites on this receptor) reversed its protective effect. The increase of protein carbonyl content induced by QA (180 nmol/site) in striatum of rats was prevented by the administration of 10 nmol/site of SPM. Besides, the bilateral striatal injection of QA (180 nmol/site) impaired the performance in the recognition memory task. The post-training striatal administration of SPM (0.1 and 1 nmol/site) reversed the QA-induced cognitive deficit. It was also evaluated whether spermine prevented QA-induced neuromorphological alterations. QA caused striatal neuronal degeneration and reactive astrogliosis. SPM, at the dose that improved the cognitive performance (0.1 nmol/site), had no effect on striatal neuronal degeneration but reversed the intense astrocytic reaction induced by QA. These results suggest that SPM has neuroprotective properties, presenting a dose dependent pattern of polyamine, in this experimental model of Huntington disease. / A espermina (SPM) é uma amina alifática, contendo quatro centros nucleofílicos e é encontrada em todas as células eucarióticas, incluindo células nervosas. Ela pertence ao grupo das poliaminas, moléculas responsáveis tanto por efeitos neuroprotetores quanto neurotóxicos. O objetivo do presente trabalho foi investigar os efeitos da SPM sobre alguns parâmetros de toxicidade induzidos pela administração estriatal de ácido quinolínico (AQ), um modelo experimental da doença de Huntington em ratos Wistar machos adultos. A administração intraestriatal unilateral de AQ (180 nmol/sítio) induziu o aparecimento de rotações contralaterais e aumento do percentual de balanços corporais contralaterais. A prévia administração estriatal de SPM mostrou efeitos diversos: na dose de 0,1 nmol/sítio aumentou o número de rotações; porém na dose de 10 nmol/sítio ela diminuiu tanto o número de rotações quanto o percentual de balanços corporais contralaterais induzidos pelo AQ. O mecanismo pelo qual a SPM diminui estas alterações motoras é, provavelmente, devido à sua interação com o receptor NMDA, uma vez que sua co-administração com a arcaína (antagonista do sítio das poliaminas neste receptor) reverteu o efeito protetor da mesma. A administração de 10 nmol/sítio de SPM preveniu o aumento do conteúdo de proteína carbonil induzida pela injeção de AQ (180 nmol/sítio) no estriado de ratos. Além disso, foi observado prejuízo cognitivo na tarefa de reconhecimento de objetos após a injeção estriatal bilateral de AQ (180 nmol/sítio). A administração estriatal póstreino de SPM (0,1 e 1 nmol/sítio) reverteu este déficit cognitivo induzido pelo AQ. Para avaliação das alterações neuromorfológicas neste modelo foram observadas degeneração neuronal e reação astrocitária. O AQ aumentou significativamente a degeneração de neurônios estriatais e a astrogliose reativa. A SPM, na menor dose que melhorou o desempenho cognitivo (0,1 nmol/sítio), não teve efeito sobre a degeneração neuronal estriatal; no entanto, ela foi capaz de reverter a intensa reação astrocitária induzida pela injeção de AQ. Estes resultados sugerem que a SPM tem propriedades neuroprotetoras, que apresentam um padrão dependente da dose da poliamina, neste modelo experimental da doença de Huntington.

The aim of this thesis was to determine the content of biogenic amines (BA)and polyamines (PA)in selected types of cheese and the influence of storage time on the content of biogenic amines.

Polyamines, specifically putrescine, spermidine, and spermine, are small cationic molecules found in all organisms. Cells can biosynthetically make these molecules, or alternatively, they can be transported from the extracellular environment. Malignant cells have been shown to require relatively high amounts of polyamines. There is a chemotherapeutic agent, DFMO, used to block the biosynthesis of polyamines. Many malignant cells can circumvent DFMO therapy by activating their transport system. A potential solution is to simultaneously block biosynthesis and transport of polyamines. However, little is known about the polyamine transport system in higher eukaryotes. This thesis aims to add to the basic biological understanding of the polyamine transport system, as well as contribute to our understanding of the way in which malignant cells are able to sustain rapid growth. This was done by screening six candidate genes believed to be involved in the polyamine transport system. These six genes were identified using various bioinformatics databases. They were screened using RNAi to knock down each gene of interest and by using an assay developed in our lab. One of the genes, RabX6, may play a possible role in the transport of putrescine.