During the differentiation and maturation of thymocytes, autoreactive cells are known to be deleted in the thymus, but the mechanism of cell death has not been elucidates. To elucidate the mechanisms involved in mosue thymocyte apoptosis induced
by
glucocorticosteroid(GCS), thymocytes were treated with stimulators or stimulators plus molecular inhibitors for various times in accordance with the purpose of this research. DNA fragmentation was analyzed by flow cytometry(FCM) and by agarose
gel
electrophoresis. The results showed that in vivo administration of GCS induced DNA fragmentation of thymus weightloss, and both wee dose dependent of the dexamethasone pellet(DEX pellet) or hydrocortisone(HC). In vitro treatment of thymocytes
with
HC ro
DEXA caused DNA fragmentation which were also dose dependent. Both drugs could split the DNA into fragments of bout 180-20bp multiples. GCS-induced DNA fragmentation was inhibited by pretreating the cells with inhibitors of RNA, protein
synthesis,
or
endonuclease. GCS- induced DNA fragmentation could be prevented by adding the protein kinase C(PKC0 inhibitor, staurosporine. Therefore, it can be concluded that PKC plays an important role in the process of thymocyte apoptosis mediated by GCS.
The
thymocytes which shwed the highest susceptabilities for the in vivo exposures to DEX pellet belonged to the subpopulation of CD4+CD8+ immature cells.
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