The scintigraphic, biodistribution and histopathological evaluation of the effect of experimental 131I administration on the gastrointestinal system and the demonstration of the Na+/I- symporter by immunohistochemistry in rats

ObjectiveThe aim of this study was to investigate histopathological changes and biodistribution of iodine-131 (I-131) in the gastrointestinal system (GIS) and also Na+/I- Symporter (NIS) presence by immunohistochemically in the experimental treatment of rats with radioactive iodine (RAI).Materials and methodsRats were divided into experimental and control groups as random early group 2 (24h), intermediate group 3 (3 weeks), and late period group 4 (3 months). Experimental groups were administered 100MBq (approximate to 3mCi, 12mCi/kg) by orogastric route with orogastric tube. Scintigraphic iodine screening images were obtained 24h, 3 weeks, and 3 months after RAI, and GIS tissues were removed, and immunohistochemical methods were used to demonstrate NIS with RAI biodistribution and histopathology.ResultsAccording to the results of scintigraphy, the most prominent activity involvement was observed in the thyroid gland at group 2, and significant activity was observed in the stomach. In the group 3 and group 4 images, owing to the physiological and biological half-life of the iodine and low resolution of the gamma camera, no secondary focal activation was observed. The highest RAI biodistribution value in all groups was in the stomach, ileum and oesophagus. In the immunohistochemical examination of NIS, the highest staining sequence was observed in all groups respectively in the stomach, oesophagus, tongue, colon, saliva, duodenum, rectum, ileum and jejunum. The increase of NIS immunohistochemically stained more intensely was observed in the RAI-administered groups.ConclusionThe amount of NIS is important for the absorption of RAI after administration.