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Master's Dissertation
DOI
https://doi.org/10.11606/D.42.2014.tde-11122014-103120
Document
Author
Full name
Ana Cláudia Munhoz
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2014
Supervisor
Committee
Curi, Rui (President)
Giannella, Maria Lucia Cardillo Correa
Ortis, Fernanda
Title in Portuguese
Participação da NADPH oxidase no processo de secreção de insulina em ilhotas pancreáticas isoladas de ratas alimentadas ou em jejum.
Keywords in Portuguese
Espécies reativas de oxigênio
Jejum
NADPH oxidase
Secreção de insulina
Abstract in Portuguese
Avaliamos importância da NADPH oxidase 2 (NOX2) na produção de espécies reativas de oxigênio (EROs) em ilhotas de ratas alimentadas ou em jejum, incubadas na presença de 2,8 mM ou 16,7 mM de glicose, associada ou não a leucina, com ou sem inibição da NOX2. As ilhotas dos animais alimentados ou em jejum apresentaram reduzida secreção de insulina e altas concentrações de EROs na presença de 2,8 mM de glicose. Esses parâmetros foram invertidos pela adição de inibidores da NOX2. A leucina, que é metabolizada no Ciclo dos Ácidos Tricarboxílicos, também aumentou a secreção de insulina por aumento de ATP, e diminuiu as EROs, devido ao aumento de NADPH, um substrato do sistema antioxidante. Desse modo, quando as ilhotas são submetidas ao jejum, a diminuição da atividade secretória é fundamental para impedir que quantidades maiores de hormônio sejam secretadas, podendo levar a uma hipoglicemia. Porém, na presença de alta concentração de glicose, a ativação das defesas antioxidantes da célula b atenua o excesso de EROS, liberando a secreção de insulina.
Title in English
NADPH oxidase participation in insulin secretion in pancreatic islets of fed or fasted rats.
Keywords in English
Fasting
Insulin secretion
NADPH oxidase
Reactive oxygen specie
Abstract in English
We sought to evaluate the importance of NADPH oxidase 2 (NOX2) in the production of reactive oxygen species (ROS) in islets from rats fed or fasted, incubated in the presence of glucose 2.8 mM or 16.7 mM, with or without leucine or inhibition of NOX2. Islets of fed or fasted animals showed reduced insulin secretion and high concentration of ROS in the presence of 2.8 mM glucose. These parameters were reversed by addition of inhibitors NOX2. Leucine that is metabolized in the cycle of Tricarboxylic Acids (TCA) also increased insulin secretion, by increasing ATP, and ROS decreased due to the increase of NADPH, a substrate of the antioxidant system. Thus, when the islets are subjected to fasting, decreased secretory activity is essential to prevent amounts of the hormone be secreted and may lead to hypoglycaemia. However, in the presence of high glucose levels, activation of antioxidant defenses of b cell attenuates the excess of ROS, releasing insulin secretion.
 
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Publishing Date
2014-12-16
 
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