Tea polyphenols protect against irradiation-induced injury in submandibular glands' cells: A preliminary study

Aim: To study the protective effect of tea polyphenols (TPs) on submandibular glands affected by radiation injury. Methods: Sixty rats were randomly divided into radiation group (R-group, N = 30) and TP-pre-treated-radiation group (TPR-group, N = 30). The rats were intragastrically administered with TP or normal sodium from 14 days before radiation, continuously daily, until the experiment. All the rats in both groups were irradiated with a single exposure dose of 15 Gy gamma rays that were delivered to the head and neck areas. Ten rats of each group were anatomised on the 3rd, 6th and 30th day after irradiation, respectively. The submandibular glands of the rats were removed for the study. The morphologic changes of the submandibular glands were observed by transmission electron microscopy (TEM). The terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labelling (TUNEL) method was used to detect apoptosis of the submandibular glands' cells. Results: Electron microscope observation of the submandibular glands showed that the lesions of the TPR-group were mild. Change in apoptosis of the cells was not obvious compared with the R-group. The cell apotosis was typical after irradiation in the R-group. Apoptosis index that was detected in the cells of submandibular glands of the TPR-group was statistically significantly decreased compared with the R-group (P < 0.01) on the 3rd, 6th and 30th day after irradiation. Conclusion: TP could protect submandibular glands from radiation injuries, and the protection mechanism may be realised by anti-apoptosis. (C) 2010 Elsevier Ltd. All rights reserved.