# Gene Expression Changes in the Spleen, Lungs, and Liver of Wistar Rats Exposed to β-Emitted 31SiO2 Particles

## TL;DR

This study examines how β-emitted 31SiO2 particles affect gene expression in the spleen, lungs, and liver of rats, focusing on biological impacts similar to those from atomic bomb residual radiation.

## Contribution

The study introduces new insights into the biological effects of β-emitted 31SiO2 particles as a model for residual radiation.

## Key findings

- 31SiO2 exposure significantly increased Cth gene expression in the liver on days 3 and 14.
- The effects of β-emitted particles were most pronounced in the liver compared to other organs.
- Internal exposure to β-emitted microparticles shows potential roles in residual radiation effects.

## Abstract

To understand the biological effects of residual radioactivity after the atomic bomb explosion in Hiroshima and Nagasaki, we previously investigated the effects of 56Mn, a major residual radioisotope. Our rat study demonstrated that inhalation exposure to 56MnO2 microparticles affected gene expression in the lungs, testes, and liver, despite the low radiation doses. Because 56Mn is a β- and γ-emitter, the differential effects between β- and γ-rays should be clarified. In this study, 31Si, a β-emitter with a radioactive half-life similar to that of 56Mn, was used to determine its effects. Male Wistar rats were exposed to sprayed neutron-activated 31SiO2 microparticles, stable SiO2 microparticles, or X-rays. The animals were examined on days 3 and 14 after irradiation. The expression of radiation-inducible marker genes, including Ccng1, Cdkn1a, and Phlda3, was measured in the spleen, lungs, and liver. Furthermore, the expressions of pathophysiological marker genes, including Aqp1, Aqp5, and Smad7 in the lungs and Cth, Ccl2, and Nfkb1 in the liver, were determined. Impacts of 31SiO2 exposure were observed mainly in the liver, where the expression of Cth markedly increased on post-exposure days 3 and 14. Our data suggest that internal exposure to β-emitted microparticles has significant biological effects and its possible roles as residual radiation after atomic bombing.