Regulação hormonal da atividade de enzimas antioxidante em orgãos Linfoides e macrofagos de ratos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The effect of insulin, thyroid hormones, glucocorticoids (dexamethasone) and catecholamines on the activity of antioxidant enzymes (CuZn- and Mn-superoxide dismutase - SOD, catalase, and glutathione peroxidase - GPX) in rat resident intraperitoneal macrophages and lymphoid organs (mesenteric lymph nodes - MLN, thymus, and spleen) was investigated. For this purpose, aduIt rats were submitted to various hormonal disfunctions such as diabetes, hyper and hypothyroidism, dexamethasone treatment and adrenodemedullation. The effect of the hormones on macrophage cuItures was also examined. In addition to the antioxidant enzyme assays, the production of hydrogen peroxide (H202) by macrophages was determined both in vivo and in vitro. In macrophages: 1) Insulin raised the activity of CuZn-SOD, catalase and GPX but reduced that of Mn-SOD, 2) Thyroid hormones increased the activity of CuZn- and Mn-SOD but decreased that of GPX, whereas dexamethasone diminished both Mn-SOD and GPX activities, 3) The removal of adrenal medulla caused a marked decrease of Mn-SOD and GPX activities, 4) H202 production was increased by insulin but reduced by thyroid hormone and dexamethasone treatment. The induction of diabetes caused the following changes in antioxidant enzyme activities of the lymphoid organs: Reduction (except for GPX) in the spleen, increase (except for Mn-SOD) in the thymus, decrease of Mn-SOD and catalase but increase of GPX in the MLN; all these changes were reversed by insulin treatment and remained unchanged under normoglycemia. The hyperthyroidism provoked an elevation of CuZn- and Mn-SOD activities and decrease of catalase in all lymphoid organs. Dexamethasone treatment caused: 1) A decrease of CuZn-SOD activity in all lymphoid organs and of Mn-SOD in the MLN, 2) A reduction of catalase activity in the MLN and thymus and an increase in the spleen, 3) An augmentation of GPX activity in the MLN, thymus and spleen. Adrenodemedullation raised CuZn-SOD activity in all lymphoid organs, decreased the activity of Mn-SOD in the MLN and spleen but increased the latter activity in the thymus, whereas catalase activity was reduced in the MLN and thymus and GPX activity became undetectable under these conditions. These findings support the proposition that the antioxidant enzyme activities are aItered by insulin, thyroid hormones, glucocorticoids and adrenalin. These metabolic changes are tissue-specific and might play a role in the impairment of the immune function under endocrine disfunctions involving these hormones

ASSUNTO(S)

insulina hormonios antioxidantes

ACESSO AO ARTIGO

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