Science & Healthcare

Introduction: The radionuclide ⁵⁶Mn (T_1/2=2.58 hours) is one of the dominant beta- and gamma-emitters within few hours after the neutron irradiation of soil dust following nuclear explosion in atmosphere. The effects of exposure to residual radioactivity from nuclear explosions are the subject of discussions and research of the consequences of nuclear tests and the atomic bombing. In order to simulate the exposure of ⁵⁶MnO₂ pulverized microparticles, experiments were carried out when the experimental rats were exposed to ⁵⁶MnO₂ dispersed powder obtained as a result of neutron activation of stable Mn atoms on a nuclear reactor.

Aim: To study the effect of dispersed ⁵⁶MnO₂ on the expression of genes in rat lung.

Materials and methods: Study design: experimental. In the experiments were used ten week-old male Wistar rats, the mass of which was 220-330 g. A total of 58 animals were used. The rats were divided into 5 groups: ⁵⁶MnO₂ (0.05 Gy), ⁵⁶MnO₂ (0.11 Gy), MnO₂, ⁶⁰Co and control. Animals were examined on days 3, 14 and 60 after exposure. Statistical analysis. All values are presented as mean ± standard error (SEM). Student’s t-test was performed to compare between the control and the radiation- exposed groups. Indicate significantly different from each contol level by p<0.01 and p<0.05.

Results: On day 3 after ⁵⁶Mn exposure, the expression of aquaporin 1 (AQP1) increased. These changes were persistent even on day 14 or day 60 in case of AQP5 expression. Interestingly, external ⁶⁰Co gamma-irradiation at a dose of 2 Gy did not change the expression of these genes (with excluding of slightly increased AQP5 gene expression on 3^rd day after irradiation). Our data suggest that internal exposure to ⁵⁶MnO₂, even at low doses, has a significant biological impact on the lungs altering the gene expression levels for a prolonged period of time, when it is compared with the effects of external radiation.

Conclusions. All this suggests that the effect of ⁵⁶MnO₂ sprayed microparticles, even with small average doses of internal light irradiation (0.11 Gy), has a very significant biological effect on this organ, as evidenced by a change in the expression levels of AQP5 genes over a very long period of time - in comparison with the external gamma irradiation of ⁶⁰Co in substantially higher doses (2 Gy). Exposure to dispersed non-radioactive MnO₂ did not result in a change in the expression of the studied genes compared to the control.