Effect of selenium on the dysfunction of rat salivary glands induced by 131I and expression of insulin-like growth factors and aquaporins.

OBJECTIVES: To investigate the effects of selenium on functional and histopathological changes and mRNA expression levels of insulin-like growth factors 1 and 2 (IGF-1 and -2) and aquaporins 4 and 5 (AQP-4 and -5) in 131 I-induced damaged rat parotid glands.

METHODS: Rats were divided into three groups: iodotherapy-with-selenium, iodotherapy-only, and control. Rats in the iodotherapy-with-selenium group were intragastrically administered 131 I on the first day and selenomethionine through drinking water. Rats in the iodotherapy-only group were only administered 131 I. Changes in parotid gland function were evaluated using the functional parameters of salivary gland dynamics imaging pre-experiment and on days 7, 30, and 90 post-treatment. Immunofluorescence and quantitative real-time PCR analyses detected IGF-1, IGF-2, AQP-4, and AQP-5 expression levels in tissues.

RESULTS: The gland-to background ratio at a maximum count (G/BG max ), T max /T min , and S max values were significantly impacted over time in the iodotherapy-with-selenium group; on day 30, the G/BG max value was significantly higher than that in the iodotherapy-only group. Histopathological analysis revealed that on days 30 and 90, the iodotherapy-with-selenium group displayed greater parotid gland repair than the iodotherapy-only group. In the iodotherapy-with-selenium group, fluorescence intensity and mRNA levels of AQP-5 increased with the selenium supplementation period, reaching significantly higher levels on days 30 and 90 than in the iodotherapy-only group. Whereas the fluorescence intensity and mRNA levels of IGF-1 in the iodotherapy-with-selenium group were significantly higher on day 7 than on day 30 in the iodotherapy-only group.

CONCLUSION: Selenium may repair 131 I-induced tissue and functional damage in rat salivary glands by upregulating AQP-5 and IGF-1 expression.