The late effects of radiation on lifespan, lymphocyte proliferation and p53 haplodeficiency in mice.
OBJECTIVE
We investigated the effect of irradiation on the lifespan of eight-week-old mice, the number of lymphocytes in bone marrow and the levels of p53 protein expression in the splenocytes.


METHODS
Eight-week-old mice, wild-type p53 (p53(+/+)) and heterozygous p53 (p53(+/-)), were irradiated with 3 Gy. The cell numbers and cell cycle phases of bone marrow cells were determined by flow cytometry. The splenocyte proliferation was evaluated by a fluorescent cell viability assay. The p53 expression was evaluated by Western blotting.


RESULTS
The lifespan of the irradiated mice was shorter than that of the non-irradiated mice. In irradiated 72-week-old p53(+/+) mice and 56-week-old p53(+/-) mice, the number of lymphocytes in bone marrow decreased as compared to that in the non-irradiated mice. In 56-week-old p53(+/-) mice, the S- and G2/M-phases of lymphocytes in the irradiated mice were increased compared to that in the non-irradiated mice. The splenocyte proliferation in p53(+/+) mice decreased with age, and the proliferation in the irradiated mice was much lower than that in the non-irradiated mice. In 72-week-old p53(+/+) mice after re-irradiation, the p53 protein expression in the splenocytes of the irradiated mice was delayed as compared to those from the non-irradiated mice.


CONCLUSIONS
We suggest that the decrease in the number of lymphocytes in bone marrow and the delayed p53 expression in splenocytes from the irradiated mice are related to the shortened lifespan after irradiation at a young age.
Okazaki
Ryuji
R
Department of Radiation Biology and Health, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan. ryuji-o@med.uoeh-u.ac.jp
Mabuchi
Yo
Y
Yoshida
Yasuhiro
Y
Suzuki
Sadafumi
S
Ding
Ning
N
Matsuzaki
Yumi
Y
Ootsuyama
Akira
A
Norimura
Toshiyuki
T
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays / Q000627:therapeutic use*; D015870:Gene Expression / Q000528:radiation effects*; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D051379:Mice; D013154:Spleen / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*
D016159:Tumor Suppressor Protein p53