| Popis: |
Previous research in this laboratory demonstrated that protein malnourishment causes increased levels of serum corticosterone and thymic atrophy in mice. The purpose of this study was to determine the effects of up-regulated serum corticosterone on thymocyte apoptosis, and the effects of a stress response on corticosterone-induced apoptosis. This study confirmed that protein malnourishment induces thymic atrophy. When mouse thymocytes were treated in vitro with corticosterone and assayed for apoptosis by quantifying phosphatidylserine externalization, mitochondrial permeabilization, andDNA fragmentation, corticosterone was shown to induce thymocyte apoptosis. When thymocytes from protein deficient mice were assayed for apoptosis, phosphatidylserine externalization and mitochondrial permeability were significantly altered, but DNA fragmentation was not. To determine how a stress response could alter thymocyteapoptosis, protein sufficient thymocytes were heat shocked and then treated with corticosterone in vitro. Heat shock decreased corticosterone-induced apoptosis and increased heat shock protein (hsp) 70 and hsp90 levels in these normal mouse thymocytes. However, when hsp70 and hsp90 were quantified in thymocytes from protein deficient mice, hsp70 or hsp90 were not significantly increased. In conclusion this study describes the significance of corticosterone-induced thymocyte apoptosis during protein malnourishment. |
