A 2 week pair-fed study of early X-irradiation effects on rat major salivary gland function

Salivary gland function is affected shortly after irradiation of the head and neck. An intense oral mucositis develops after exposure and may interfere with ingestion. The effects of restricted food and water intake on the secretory output of rat major salivary glands were examined. Parotid and submandibular salivary output and body weight were measured in rats at 4, 8, 11 and 14 days after 15 Gy X-irradiation of the head and neck. Comparisons were made with two groups: a non-irradiated group with food and water intake restricted to that of the irradiated group (pair-fed), and a non-irradiated, ad libitum-fed control group. Parotid saliva output was significantly decreased in the irradiated group at 4, 8 and 11 days compared with the control group. The pair-fed rats also had significantly decreased parotid output at these time points and their parotid function did not differ from that of the irradiated animals. At 14 days, all three groups demonstrated similar parotid function. Submandibular salivary output was not affected to the same extent. Only at a single time point (11 days) was flow significantly decreased in the irradiated group. Total body weight was less than that of control rats for both the irradiated and pair-fed animals at all time points. These results suggest that the early effects of radiation on salivary glands are due, in part, to limited intake of food and water during the immediate post-irradiation period.