Laminarin attenuates irradiation-induced salivary gland hypofunction in mice: association with enhanced Nrf2-associated antioxidant responses.

Radiotherapy-induced salivary gland (SG) hypofunction substantially impairs the quality of life for patients with head and neck cancer, while effective preventive treatments remain limited. This study investigated the protective effects of laminarin against SG injury in mice and its association with Nrf2-related antioxidant responses. Mice received a single 15-Gy head and neck irradiation and were assessed 28 days later. Body weight, food and water intake, stimulated salivary flow rate, submandibular gland weight, histopathological changes, AQP5 expression, oxidative stress indicators, and Nrf2-associated proteins were evaluated. Irradiation reduced body weight, food intake, SG weight, salivary secretion, and AQP5 expression, while increasing water intake, histopathological injury, ROS, and MDA levels. Laminarin ameliorated these changes, preserved SG function, increased MnSOD expression, and reduced oxidative stress. Laminarin treatment was also accompanied by higher nuclear Nrf2 protein levels and increased HO-1 and NQO1 expression. These findings indicate that laminarin attenuates irradiation-induced SG hypofunction and oxidative injury in mice and suggest a possible association with enhanced Nrf2-associated antioxidant responses. The present study provides preclinical evidence supporting further evaluation of laminarin as a potential radioprotective strategy for preserving SG function during head and neck radiotherapy.