Abstract:
The investigation of the radiation effects of the atomic bombing in Hiroshima and Nagasaki has revealed concerns about the impact of the residual radioactive dust produced in the soil.
Manganese-56 is one of the major radioisotopes produced by neutrons from the bomb; hence, we
previously examined the biological effects of manganese dioxide-56 (56MnO2
) in Wistar rats, in which
significant changes were found in the lung. In the present study, ten-week-old male C57BL mice
were exposed to three doses of radioactive 56MnO2
, stable MnO2 particles, or external γ-rays (2 Gy)
to further examine the effects of 56MnO2
in a different species. The estimated absorbed radiation
doses from 56MnO2 were 26, 96, and 250 mGy in the lung. The animals were examined at 3, 14, and
70 days post exposure. Histologically, no exposure-related changes were found in the lungs of any
group. However, pulmonary mRNA expression of aquaporin 1, which is a useful marker for lung
pathophysiology, was significantly elevated at 14 and 70 days, although no such changes were found
in the mice exposed to external γ-rays (2 Gy). These data indicated that the inhalation exposure
to 56MnO2 particles, with <250 mGy of organ doses, produced significant biological responses in
the lung.
