Depressive-like symptoms induced by chronic low-dose exposure to radiation in mice were suppressed by fecal transplants from unexposed mice

Professionals who have been exposed to low-dose ionizing radiation for a long time are known to sometimes display symptoms similar to lethargy; however, the mechanism responsible is unknown. Therefore, we evaluated “motivation for exploration” and “interest in new things”, and examined whether radiation affects the mental state of rodents. We found that mice exposed to long-term low-dose irradiation (a total dose of 0.3 Gy in 10 weeks) did not change the amount of exercise itself, but their motivation for exploration was clearly reduced, and they showed no interest in other individuals, which indicates an abnormal psychological effect. We also investigated the relationship between intestinal bacteria and the low-dose effect by transplanting healthy stools from non-irradiated mice into mice whose behavior changed due to low-dose fractionated irradiation. Fecal transplantation improved the behavior of individuals in the irradiated group, in which the time to find the escape box of the Barnes maze behavioral test was the same as that in the non-irradiated control group, and the involvement of intestinal bacteria in negating the effects of radiation was considered.