To investigate the effect of amifostine, we administered amifostine, a radioprotective agent, 30 minutes before exposing the maxillary region of mice, including the parotid gland, to 5 Gy or 10 Gy X-ray irradiation. The survival rate was recorded, and changes in the parotid gland morphology were investigated by examining the hematoxylin and eosin (HE)-stained specimens and light microscope autoradiography (LMARG) images obtained 30 days after irradiation. A survival rate of 100% was not observed in any group administered 200 mg/kg amifostine with or without irradiation. Among the groups irradiated with 10 Gy X-rays, the survival rate was higher and the survival period was longer in the 100 mg/kg amifostine group than in the no amifostine group. The histological findings in the group that received 5 Gy irradiation without amifostine were as follows: auxetic growth of acinar cells, nuclei of all sizes, cells in the mitotic phase, and cells undergoing apoptosis. Further, the treated groups were compared with the no amifostine and no irradiation group (untreated control). LMRG imaging revealed that the number of reduced silver grains per mm² of acinar cells after 30 min of ³H-leucine administration was higher than that after 120 min in mice treated with 100 mg/kg amifostine with or without 5 Gy irradiation. This observation was similar to that in the untreated control.This finding suggests that although amifostine administration reduces the adverse effects of irradiation on the parotid gland, higher doses of amifostine may be fatal.

In order to examine the influence of X-ray irradiation on the demilune cells of the sublingual gland due to the existence of secretory granules, 10 Gy of X-ray irradiation was applied to the sublingual gland of mice at 3 hours after isoproterenol (IPR) administration. To inspect the influence of irradiation at 3 days after the irradiation, tissue images and results of autoradiography performed at 30 and 120 minutes (min) after ³H-leucine administration of the IPR administration (IPR/10Gy) group were compared with those of the non-IPR administration (nonIPR/10Gy) group. In transmission electron microscope images, swelling and pyknosis were observed in the rough endoplasmic reticulum of the nonIPR/10Gy group. The number of reduced silver grains per unit cell area in nonIPR/10Gy at 30 and 120 min after ³H-leucine administration was less and greater than that in the other 3 groups (nonIPR/0Gy, IPR/0Gy, and IPR/10Gy), respectively, from light microscope autoradiography images. At 120 min after ³H-leucine administration, the ratio of the number of reduced silver grains localized in the secretory granules to the total number of reduced silver grains in the demilune cells of the nonIPR/10Gy group was lower than that of the other 3 groups as indicated by electron microscope autoradiography images. Based on these results, it was apparent that the effect of irradiation was less on the demilune cells that discharged secretory granules than those that did not discharge them.