ABSTRACT
Objective To investigate the expressions of NBS1 mRNA and protein in the salivary gland of irradiated rats and explore the role of NBS1 in the repair of radiation injury of salivary gland epithelial cells.Methods Eighty rats were randomly divided into two groups for radiation and control (n =40 each).The rats were fractionally exposed to 3 Gy of 60Co γ-rays once in two days,leading to an accumulation dose of 3,6,9,12,15 Gy.The sham-irradiated controls were anesthetized in parallel but without irradiation.After 2-4 h of irradiation,the rats were sacrificed,IHC and RT-PCR were used to detect the expressions of NBS1 protein and mRNA in parotid and submandibular glands,and the ultra-structural changes in the glands were observed by a transmission electron microscopy.Results After irradiation,the salivary glands became atrophy and the parotid gland cells were damaged more serious than the submandibular gland cells.Compared with the controls,with the groups of dose,at 9,12,15 Gy in parotid gland (t =7.10,17.93,20.86,P ＜ 0.05),at 12,15 Gy in the submandibular gland (t =3.13,7.53,P ＜0.05),the expression of NBS1 mRNA was reduced.With the groups of dose at 9,12,15 Gy in paretid gland (t =4.29,17.91,91.29,P ＜ 0.05 ),the dose at 12,15 Gy in submandibular gland ( t =4.61,11.84,P＜0.05),the expression of NBS1 protein in serous cells,and the dose at 12,15 Gy in parotid gland ductal epithelial cell ( t =3.09,5.62,P ＜ 0.05) were reduced.But in the ductal epithelial cells as well as muoass cells in the submandibualr gland were steadily.Conclusions After irradiation,NBS1 at both protein and mRNA levels was dropped in the salivary gland of rats,which might contribute to the repair of radiation injury of salivary gland.