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Master's Dissertation
DOI
10.11606/D.60.2008.tde-08092008-231104
Document
Author
Full name
Vânia Brazão
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2008
Supervisor
Committee
Prado Junior, Jose Clovis do (President)
Natsui, Ana Patricia Yatsuda
Rosa, Joao Aristeu da
Title in Portuguese
Administração de zinco de dehidroepiandrosterona (DHEA): exerceriam eles um papel sinérgico na resposta imune de ratos senis infectados com Trypanosoma cruzi?
Keywords in Portuguese
Dehidroepiandrosterona
Ratos Wistar
Trypanosoma cruzi
Zinco
Abstract in Portuguese
A modulação das respostas imunológicas frente à administração de substâncias farmacologicamente ativas em modelos experimentais infectados por Trypanossoma cruzi tem contribuído de maneira importante nas investigações de novas terapias para a doença de Chagas. O presente estudo teve como objetivo avaliar um possível efeito sinérgico imunoestimulatório subseqüente à administração de sulfato de zinco e DHEA durante o curso da infecção. O DHEA tem sido amplamente estudado e possui ação comprovada no direcionamento da resposta imune Th1, sendo muito efetivo para diferentes patógenos tais como vírus, bactérias e protozoários. O zinco é considerado um oligoelemento de extrema importância para a manutenção das funções imunes. Age como um inibidor da apoptose celular além de coordenar a seleção fisiológica de células intra-tímicas. Durante a fase aguda da infecção, zinco e DHEA apresentaram atividade estimulatória sobre a imunidade do hospedeiro, potencializando a resposta imune gerada contra o parasita. Comprovamos também a ação sinérgica de DHEA e zinco, através dos parâmetros analisados tais como parasitemia sangüínea e tecidual, além de fatores imunológicos como aumento nas concentrações de NO, IFN-?, IL-12, e número de macrófagos. Este efeito imuno-modulador durante a fase aguda da infecção chagásica pode contribuir para a prevenção dos danos teciduais observados na fase crônica da doença.
Title in English
Administration of zinc and dehydroepiandrosterone (DHEA): would they exert a synergic role in the immune response of aged Wistar rats infected with Trypanosoma cruzi?
Keywords in English
Dehydroepiandrosterone
Trypanosoma cruzi
Wistar rats
Zinc
Abstract in English
The modulation of the immune responses as well as the administration of pharmacologically active substances in infected T. cruzi experimental models has contributed to important investigations of new therapies in the treatment of Chagas' disease. However, the use of antiparasitary drugs in the chronic indeterminate or in the cardiac chronic phases of Chagas disease is still a controversial issue. This study has as objectives to evaluate a possible synergic immunostimulatory effect after the administration of zinc and DHEA during the course of the infection. A bulk of evidences has been presented confirming the effectiveness action of DHEA on the Th1 immune response against a wide range of pathogens such like viruses, bacteria and protozoans. Zinc is considered an oligoelement of essential importance in the maintenance of the immune functions, as well as inhibiting cell apoptosis besides the function of coordinate the physiological selection of thymic T cells. During the acute phase of infection, zinc and DHEA displayed enhanced stimulatory activity on host's immune response. A synergistic action of zinc and DHEA was also observed through the evaluations of distinct parameters such as blood and tissue parasitism, number of macrophages and NO levels as well as elevated concentrations of some immunological interleukins such as IFN-? and IL-12. This work also demonstrates that the enhanced immunostimulatory effect observed during the acute phase certainly contributes in the prevention of tissue damage that normally occurs during the late chronic phase.
 
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Dissert.pdf (1.93 Mbytes)
Publishing Date
2008-09-11
 
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