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The Journal of the Korean Society for Therapeutic Radiology and Oncology 2001;19(2): 146-152. |
| Regulation of Apoptosis and Cell Cycle in Irradiated Mouse Brain |
| Won Yong Oh, Mi Hee Song, Eun Ji Chung, Jin Sil Seong, Chang Ok Suh |
1Department of Therapeutic Radiology, National Medical Center.
2Department of Radiation Oncology, Yonsei University, College of Medicine, Yonsei Cancer Center, Seoul, Korea. |
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| ABSTRACT |
PURPOSE:
To investigate the regulation of apoptosis and cell cycle in mouse brain irradiation.
MATERIALS AND METHODS:
8-week old male mice, C57B1/6J were given whole body gamma-radiation with a single dose of 25 Gy using Cobalt 60 irradiator. At different times 1, 2, 4, 8 and 24hr after irradiation, mice were killed and brain tissues were collected. Apoptotic cells were scored by TUNEL assay. Expression of p53, Bcl-2, and Bax and cell cycle regulating molecules; cyclins B1, D1, E and cdk2, cdk4, p34cdc2 were analysed by Western blotting. Cell cycle was analysed by Flow cytometry.
RESULTS:
The peak of radiation induced apoptosis is shown at 8 hour after radiation. With a single 25 Gy irradiation, the peak of apoptotic index in C57B1/6J is 24.0+/-0.25 (p<0.05) at 8 hour after radiation. Radiation upregulated the expression of p53/tubulin, Bax/tubulin, and Bcl-2/tubulin with 1.3, 1.1 and 1.45 fold increase, respectively were shown at the peak level at 8 hour after radiation. The levels of cell cycle regulating molecules after radiation are not changed significantly except cyclin D1 with 1.3 fold increase. Fractions of Go-G1, G2-M and S phase in the cell cycle does not specific changes by time.
CONCLUSIONS:
In mouse brain tissue, radiation induced apoptosis is particularly shown in a specific area, subependyma. These results and lack of radiation induced changes in cell cycle offer better understanding of radiation response of normal brain tissue. |
| Key Words:
Mouse brain(cerebrum) irradiation, Apoptosis, Cell cycle |
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