Study of the determining mechanisms of the hyporeactivity of mast cells in diabetes experimental induced for alloxan in rats.
In this work, we aimed to determine the mechanisms involved in the refractoriness of mast cells associated with diabetes caused by alloxan in rats. We found that isolated peritoneal mast cells from diabetic animals were hyporeactive to antigen stimulation, a phenomenon which was extensive to other body sites including skin, trachea and intestine. We noted by means of adoptive transfer system, that repopulation of the pleural cavity with mast cells restored the reactivity of diabetic rats to antigenic provocation. Moreover, the transfer of sensitized mast cells from diabetics to naive animals led to a lower allergen-induced exudation as compared to the response noted after transfer of sensitized naive mast cells. Such phenomenon was also detected in vitro. Isolated mast cells showed themselves less reactive to several stimuli including antigen, bradykinin and compound 48/80, as attested by the release of lower amounts of histamine and PGD2. In addition, diabetic mast cells presented higher levels of cAMP, in a clear association with increased content of actin microfilaments and apoptotic rate. Pre-treatment of diabetic rats with RU 486 inhibited the refractoriness of diabetic mast cells, indicating that this phenomenon seems to be associated with elevation in the levels of steroids hormones detected in diabetes. In addition, despite thymus dysfunction attested by atrophy and elevation in extracellular matrix deposition, the mast cell population remained unchanged. This indicated that thymic mast cells seem to be under different regulation as compared to those present in other tissue sites.
Advisor:Patrícia Machado Rodrigues e Silva
School:Faculdades Oswaldo Cruz
Source Type:Master's Thesis
Keywords:Mastócito Diabetes mellitus experimental Aloxana Mast cells Hypersensitivity Apoptosis Alloxan
Date of Publication:03/28/2006