J Korean Med Sci.  2006 Dec;21(6):1103-1107. 10.3346/jkms.2006.21.6.1103.

Adaptive Responses Induced by Low Dose Radiation in Dentate Gyrus of Rats

• Kang JO
• Hong SE
• Kim SK
• Kim CJ
• Lee TH
• Chang HK
• Shin MS
• Kim H

• KMID: 1713127
• DOI: http://doi.org/10.3346/jkms.2006.21.6.1103

Abstract

The purpose of this study is to investigate the mechanism of alternative responses to low dose irradiation for neuronal cell proliferation in the dentate gyrus of rats. To determine the effect of a single exposure to radiation, rats were irradiated with a single dose of 0.1, 1, 10 or 20 Gy. To determine the effect of the cumulative dose, the animals were irradiated daily with 0.01 Gy or 0.1 Gy from 1 to 4 days. The neuronal cell proliferation was evaluated using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Four consecutive daily irradiations with a 0.01 Gy/fraction increased the number of BrdU-positive and Ki-67-positive cells in a dose dependent manner, but this did not affect the number of TUNEL-positive cells. However, there was not a dose dependent relationship for the 0.1 Gy/fraction irradiation with the number of BrdU, Ki-67 and TUNEL positive cells. Our data support the explanation that the adaptive response, induced by low-dose radiation, in the hippocampus of rats is more likely a reflection of the perturbations of cell cycle progression.

Keyword

Adaptive Response; Radiation Effects; Hippocampus Neurons

MeSH Terms

Rats, Sprague-Dawley
Rats
Radiation Dosage
Neurons/*cytology/*radiation effects
Neuronal Plasticity/*radiation effects
Male
Dose-Response Relationship, Radiation
Dentate Gyrus/*cytology/*radiation effects
Cell Survival/radiation effects
Cell Proliferation/*drug effects
Animals
Adaptation, Physiological/radiation effects

Figure

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  Fig. 1 The effect of a single dose on the 5-bromo-2'-deoxyuridine (BrdU), Ki-67, and TUNEL positive cells in the dentate gyrus of rats. The Brd-U positive and Ki-67 positive cells are increased after 0.1 Gy radiations. The change of the number of apoptotic cells is minimal with 0.1 Gy radiation but dramatically increases as the dose increased.

• 

  Fig. 2 The effect of cumulative dose on the 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and TUNEL positive cells in the dentate gyrus of rats. The Brd-U positive and Ki-67 positive cells are increased with 0.01 Gy/fraction radiation as the dose increased. But with 0.1 Gy/fraction radiation, Brd-U positive and Ki-67 positive cells show a peak at 0.1 Gy and decrease afterward as the dose increased. The number of apoptotic cells do not show significant alterations with both 0.01 Gy/fraction and 0.1 Gy/fraction radiation although the dose was accumulated. Open circle: 0.01 Gy radiation group. Closed circle: 0.1 Gy radiation group.

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