Rat salivary gland function after fractionated irradiation

The aim of this study was to investigate longitudinal effects of fractionated irradiation, with various total doses, on salivary gland function in the rat. Female Sprague-Dawley rats were irradiated with 4, 5, 6, 7 or 8 Gy per day on five consecutive days. Irradiation was given to the head and neck region. Whole saliva was collected before and 2, 15 and 26 weeks after irradiation. In general the effects of irradiation on salivary gland function were found to be related to dose and time after exposure. Secretion rates were significantly decreased two weeks after irradiation with doses of 30 Gy or higher, after 15 weeks with 25 Gy or higher, and after 26 weeks with 20 Gy or higher. Response patterns to irradiation differed between the salivary constituents. Thus, the conclusions from this study are that early and late effects display different patterns and that the model used to study variations in salivary gland function after fractionated irradiation must be adjusted to the question addressed.