Long-term salivary effects of single-dose head and neck irradiation in the rat

The effect of a single dose of X-irradiation (either 2.5, 5, 7.5, 10 or 15 Gy) to the head and neck region on parotid and submandibular gland function in rats was evaluated for up to 1 year. No animal receiving 15 Gy survived the entire study. Animals receiving ≥7.5 Gy showed significantly less increase in body weight over time. Average wet weights of both gland types were reduced with as little as 2.5 Gy. Pilocarpine-stimulated parotid salivary flow was diminished significantly at 12 months for each radiation-dose group. Significant salivary flow reductions from submandibular glands were seen at ≥7.5 Gy at this same time-point. These results show that a single radiation exposure of as low as 2.5 Gy to the head and neck region of rats can cause significant long-term alterations in salivary gland function.