Whole-body γ-irradiation decelerates rat hepatocyte polyploidization.

Purpose: To characterize hepatocyte polyploidization induced by intermediate dose of γ-ray.

Materials And Methods: Male Wistar strain rats were whole-body irradiated (WBI) with 2 Gy of γ-ray at the age of 1 month, and 5-6 rats were sacrificed monthly at 0-25 months after irradiation. The nuclear DNA content of individual hepatocytes was measured by flow cytometry, then hepatocytes were classified into various ploidy classes.

Results: Survival percentage, after exposure up to the end of the study, did not indicate any differences between the irradiated groups and controls. The degree of polyploidization in hepatocytes of irradiated rats, was significantly lower than that for the control after 1 month of exposure, and it continued to be lower after up to 8 months. Thereafter, the degree of polyploidization in the irradiated group slowly returned to the control level when the irradiated rats reached the age of 10 months.

Conclusion: Intermediate dose of ionizing radiation, in contrast to high doses, decelerate hepatocyte polyploidization, which may coincides with the hypothesis of the beneficial effects of low doses of ionizing radiation.