Purpose: To evaluate how irradiation affects thyroid autoimmunity in mouse models of Hashimoto's thyroiditis and Graves' hyperthyroidism. Materials and methods: Non-obese diabetic (NOD)-H2^h4 mice spontaneously develop anti-thyroglobulin (Tg) antibodies and thyroiditis when supplied with sodium iodine (NaI) in the drinking water. BALB/c mice develop anti-thyrotropin receptor (TSHR) antibodies and hyperthyroidism following immunization with adenovirus expressing TSHR (Ad-TSHR). Mice were irradiated as follows: A single whole-body irradiation with 0.05, 0.5 or 3 Gy one week before or after the beginning of NaI or immunization with Ad-TSHR, fractionated whole-body irradiations with 0.05 Gy twice a week or 0.5 Gy once a week from one week before NaI or Ad-TSHR immunization, or a single regional irradiation to the thyroid gland with 0.5 Gy one week before NaI. The effect of a single irradiation with 0.05, 0.5 or 3 Gy on splenocytes was also evaluated. Results: A single whole-body irradiation with 0.5 Gy one week before NaI exacerbated thyroiditis and increased anti-Tg antibody titers in NOD-H2^h4 mice. In contrast, any irradiation protocols employed did not affect incidence of hyperthyroidism or anti-TSHR antibody titers in BALB/c mice. High-dose irradiation increased the relative ratios of effector T cells to regulatory T cells (an indication of enhanced immune status) but kills most of T cells. Conclusions: These results indicate that a single whole-body low-dose irradiation with 0.5 Gy exacerbates thyroiditis in NOD-H2^h4 mice, data consistent with some clinical evidence for increased incidence of thyroid autoimmunity by environmental irradiation.

We aimed to investigate the lifestyle factors influencing weight gain among university students in Japan during the mild lockdown imposed due to the novel coronavirus disease pandemic. In this cross-sectional study, we conducted a questionnaire survey of students who underwent health examinations at Nagasaki University in 2021. Students reporting a weight gain of ≥3 kg were included in the weight gain group; the remaining students were included in the non-weight-gain group. Fisher’s exact test and binary logistic regression were performed to determine the association between weight gain and each lifestyle factor. We included 3059 respondents (response rate: 45.7%), and 9.5% of them reported a weight gain of ≥3 kg. The following factors were associated with weight gain (odds ratio (95% confidence interval), p value based on Fisher’s exact test): dining out for four times or more/week (2.16 (1.40, 3.32), p = 8.7 × 10⁻⁴) and gaming time of ≥4 h/day (2.26 (1.45, 3.47), p = 2.4 × 10⁻⁴). Binary logistic regression among the four highest odds ratios revealed that after adjusting for other factors, frequent dining out and prolonged gaming time were significantly associated with weight gain in students during the mild lockdown.