Apoptosis and expression of AQP5 and TGF-beta in the irradiated rat submandibular gland.

PURPOSE To evaluate the effect of X-ray irradiation on apoptosis and change of expression of aquaporin 5 (AQP5) and transforming growth factor-β(TGF-β) in the rat submandibular gland (SMG). MATERIALS AND METHODS SMGs of 120 male Sprague-Dawley rats were irradiated with a single X-ray dose (3, 10, 20, or 30 Gy). At the early and late post-irradiation phase, apoptosis was measured by the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) method, and expression of AQP5 and TGF-β was determined by immunohistochemical staining. RESULTS At the late post-irradiation phase, increased apoptosis was evident and marked decreases of expression of AQP5 expression by acinar cells and TGF-β expression by ductal cells were evident. CONCLUSION Apoptosis after X-ray irradiation develops relatively late in rat SMG. Irradiation reduces AQP5 and TGF-β expression in different SMG cell types.