Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 3 uppsatser.

Yes / The ability to either erase or update the memories of a previously learned spatial task is an essential process that is required to modify behaviour in a changing environment. Current evidence suggests that the neural representation of such cognitive flexibility involves the balancing of synaptic potentiation (acquisition of memories) with synaptic depression (modulation and updating previously acquired memories). Here we demonstrate that the p38 MAPK/MAPK-activated protein kinase 2 (MK2) cascade is required to maintain the precise tuning of long-term potentiation and long-term depression at CA1 synapses of the hippocampus which is correlated with efficient reversal learning. Using the MK2 knockout (KO) mouse, we show that mGluR-LTD, but not NMDAR-LTD, is markedly impaired in mice aged between 4 and 5 weeks (juvenile) to 7 months (mature adult). Although the amplitude of LTP was the same as in wildtype mice, priming of LTP by the activation of group I metabotropic receptors was impaired in MK2 KO mice. Consistent with unaltered LTP amplitude and compromised mGluR-LTD, MK2 KO mice had intact spatial learning when performing the Barnes maze task, but showed specific deficits in selecting the most efficient combination of search strategies to perform the task reversal. Findings from this study suggest that the mGluR-p38-MK2 cascade is important for cognitive flexibility by regulating LTD amplitude and the priming of LTP. / Professor Richard Greene at the University of Bradford - startup fund to setup electrophysiological facility and Wellcome Trust 200646/Z/16/Z to S.A.L.C.

Partículas da exaustão de motores a diesel (DEP) têm propriedades toxicológicas, devido às características físico-químicas. O DEP é capaz de ativar as vias de sinalização intracelular e induzir alterações metabólicas em células e tecidos do sistema respiratório. O objetivo desta tese foi: 1) avaliar o perfil das mucinas e alterações epiteliais em explantes de traqueia de camundongo BALB/c expostos ao DEP e DEP tratado com ácido nítrico e solventes orgânicos; e 2) em cultura de células de epitélio brônquico humano (BEAS-2B) expostas ao DEP e DEP tratado com hexano (DEP/HEX) para avaliar ativação de MAPK (ERK e JNK), citotoxidade, integridade de citoesqueleto, viscoelasticidade celular e expressão gênica de enzimas envolvidas no estresse oxidativo e apoptose. Os resultados mostraram que, em explantes de traqueia, o DEP causa aumento significativo em relação ao grupo controle na quantidade de muco ácido (p= 0,001), diminuição no muco neutro (p=0,001), diminuição de muco misto (p= 0,001), aumento de vacuolização (p= 0,001), aumento de apoptose (p=0,001), ora com aumento de pERK e diminuição de pJNK, e vice-versa. Os explantes submetidos à exposição ao DEP e DEP/MET aumentaram significativamente o muco ácido (p=0,01) e DEP/HEX provocou aumento da extrusão do muco (p=0,007), provavelmente devido à ação do enriquecimento inorgânico. Para as células BEAS-2B, nos resultados obtidos com células epiteliais expostas ao DEP e DEP/HEX, foram observadas alterações na membrana citoplasmática, mitocôndrias e citoesqueleto. As células expostas apenas ao DEP em baixas concentrações (15ug/mL) apresentaram alterações na expressão de genes envolvidos no apoptose (BCL-2 e Caspase-3 (p=0,05 e p=0,01) e estresse oxidativo [(SOD1 e SOD2 e GPx. p=0,01 )], e CYP1A1 ((p=0,01) / Diesel exhaust particles (DEPs) from diesel engines have toxic properties that result from their physical and chemical characteristics. DEPs are able to activate intracellular signaling pathways and induce metabolic changes to cells and tissues of the human respiratory system. This dissertation sought to evaluate: 1) the profile of mucins and the epithelial changes to the tracheal explants of BALB/c mice exposed to both DEP and DEP treated with nitric acid and organic solvents (50 and 100 ug/mL; and 2) human bronchial epithelial cells (BEAS-2B) in culture after their exposure to both DEP and DEP treated with hexane (DEP/HEX) at 100 ug/mL in order to determine MAPK (ERK/JNK) activation, cytotoxicity, cytoskeletal integrity, cell viscoelasticity and gene expression of the enzymes involved in oxidative stress and apoptosis. The results show that, in tracheal explants, DEP causes a significant increase (compared to the control) in the quantity of acidic mucus (p=0.001), a decrease in alkaline mucus (p=0.001), a decrease in mixed mucus (p=0.001), an increase in vacuolization (p=0.001), an increase in apoptosis (p=0.001), along with an increase in pERK and a decrease in pJNK, and vice versa. The explants that were exposed to DEP and DEP/MET were found to have significantly higher quantities of acidic mucus (p=0.01), and DEP/HEX caused an increase in mucus extrusion (p=0.007), which was likely due to inorganic enrichment. In the case of BEAS-2B cells, the results obtained from epithelial cells exposted to DEP and DEP/HEX revealed alterations in the cytoplasmic membrane, the mitochondria, and the cytoskeleton. The cells exposed to DEP alone at low concentrations (15 ug/mL) experienced alterations in the genes involved in apoptosis (BCL-2 and Caspase-3; p=0.05 and p=0.01, respectively), as well as oxidative stress [(SOD1, SOD2, and GPx; p=0.01 )], and changes to CYP1A1 (p=0.01)

Partículas da exaustão de motores a diesel (DEP) têm propriedades toxicológicas, devido às características físico-químicas. O DEP é capaz de ativar as vias de sinalização intracelular e induzir alterações metabólicas em células e tecidos do sistema respiratório. O objetivo desta tese foi: 1) avaliar o perfil das mucinas e alterações epiteliais em explantes de traqueia de camundongo BALB/c expostos ao DEP e DEP tratado com ácido nítrico e solventes orgânicos; e 2) em cultura de células de epitélio brônquico humano (BEAS-2B) expostas ao DEP e DEP tratado com hexano (DEP/HEX) para avaliar ativação de MAPK (ERK e JNK), citotoxidade, integridade de citoesqueleto, viscoelasticidade celular e expressão gênica de enzimas envolvidas no estresse oxidativo e apoptose. Os resultados mostraram que, em explantes de traqueia, o DEP causa aumento significativo em relação ao grupo controle na quantidade de muco ácido (p= 0,001), diminuição no muco neutro (p=0,001), diminuição de muco misto (p= 0,001), aumento de vacuolização (p= 0,001), aumento de apoptose (p=0,001), ora com aumento de pERK e diminuição de pJNK, e vice-versa. Os explantes submetidos à exposição ao DEP e DEP/MET aumentaram significativamente o muco ácido (p=0,01) e DEP/HEX provocou aumento da extrusão do muco (p=0,007), provavelmente devido à ação do enriquecimento inorgânico. Para as células BEAS-2B, nos resultados obtidos com células epiteliais expostas ao DEP e DEP/HEX, foram observadas alterações na membrana citoplasmática, mitocôndrias e citoesqueleto. As células expostas apenas ao DEP em baixas concentrações (15ug/mL) apresentaram alterações na expressão de genes envolvidos no apoptose (BCL-2 e Caspase-3 (p=0,05 e p=0,01) e estresse oxidativo [(SOD1 e SOD2 e GPx. p=0,01 )], e CYP1A1 ((p=0,01) / Diesel exhaust particles (DEPs) from diesel engines have toxic properties that result from their physical and chemical characteristics. DEPs are able to activate intracellular signaling pathways and induce metabolic changes to cells and tissues of the human respiratory system. This dissertation sought to evaluate: 1) the profile of mucins and the epithelial changes to the tracheal explants of BALB/c mice exposed to both DEP and DEP treated with nitric acid and organic solvents (50 and 100 ug/mL; and 2) human bronchial epithelial cells (BEAS-2B) in culture after their exposure to both DEP and DEP treated with hexane (DEP/HEX) at 100 ug/mL in order to determine MAPK (ERK/JNK) activation, cytotoxicity, cytoskeletal integrity, cell viscoelasticity and gene expression of the enzymes involved in oxidative stress and apoptosis. The results show that, in tracheal explants, DEP causes a significant increase (compared to the control) in the quantity of acidic mucus (p=0.001), a decrease in alkaline mucus (p=0.001), a decrease in mixed mucus (p=0.001), an increase in vacuolization (p=0.001), an increase in apoptosis (p=0.001), along with an increase in pERK and a decrease in pJNK, and vice versa. The explants that were exposed to DEP and DEP/MET were found to have significantly higher quantities of acidic mucus (p=0.01), and DEP/HEX caused an increase in mucus extrusion (p=0.007), which was likely due to inorganic enrichment. In the case of BEAS-2B cells, the results obtained from epithelial cells exposted to DEP and DEP/HEX revealed alterations in the cytoplasmic membrane, the mitochondria, and the cytoskeleton. The cells exposed to DEP alone at low concentrations (15 ug/mL) experienced alterations in the genes involved in apoptosis (BCL-2 and Caspase-3; p=0.05 and p=0.01, respectively), as well as oxidative stress [(SOD1, SOD2, and GPx; p=0.01 )], and changes to CYP1A1 (p=0.01)