Protective effects of alpha lipoic acid on radiation-induced salivary gland injury in rats

Purpose: Radiation therapy is a treatment for patients with head and neck (HN) cancer. However, radiation exposure to the HN often induces salivary gland (SG) dysfunction. We investigated the effect of a-lipoic acid (ALA) on radiation-induced SG injury in rats. Results: ALA preserved acinoductal integrity and acinar cell secretary function following irradiation. These results are related to the mechanisms by which ALA inhibits oxidative stress by inhibiting gp91 mRNA and 8-OHdG expression and apoptosis of acinar cells and ductal cells by inactivating MAPKs in the early period and expression of inflammation-related factors including NF-kappa B, I kappa B-alpha, and TGF-beta 1 and fibrosis in late irradiated SG. ALA effects began in the acute phase and persisted for at least 56 days after irradiation. Materials and Methods: Rats were assigned to followings: control, ALA only (100 mg/kg, i.p.), irradiated, and ALA administered 24 h and 30 min prior to irradiation. The neck area including the SG was evenly irradiated with 2 Gy per minute (total dose, 18 Gy) using a photon 6-MV linear accelerator. Rats were killed at 4, 7, 28, and 56 days after radiation. Conclusions: Our results show that ALA could be used to ameliorate radiationinduced SG injury in patients with HN cancer.