Protective effects of a cystine and theanine mixture against acute radiation injury in rats.

This study aims to examine the effects of cystine and theanine (CT), which increases glutathione biosynthesis, on the survival rate and acute radiation injury of the small intestine and bone marrow using a rat model. CT pre-treatment (280 mg/kg for 5 days) significantly improved weight loss and survival rate of rats as compared with the control group after 5 Gy. CT pre-treatment significantly increased the rate of mucosa and crypt length, and decreased the number of apoptotic cells, TUNEL and cleaved caspase-3 positive cells, while increasing the number of mitotic cells and Ki-67 positive cells in jejunal crypts and villi compared to control rats post-irradiation. CT also suppressed bone marrow cell loss and reduced the number of apoptotic cells in bone marrow. These results suggest a protective effect of CT pre-treatment for acute injury after irradiation through apoptosis inhibition and increased proliferative activity in jejunal crypt cells and bone marrow cells.