Injury in Minipig Parotid Glands following Fractionated Exposure to 30 Gy of Ionizing Radiation

Abstract

Objective To explore the effects of 30 Gy of 60Co γ-rays on apoptosis and reactive oxygen species (ROS) levels in minipig parotid cells as a possible mechanism for radiation-induced parotid injury. Study Design Experimental study. Setting Department of Radiotherapy, First Affiliated Hospital, Guangxi Medical University, Nanning, China. Subjects and Methods Forty male minipigs were divided into control and irradiated groups. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling was used for detecting apoptosis in the parotid cells, immunohistochemistry, and western blots were used to test expression of the B-cell lymphoma 2 (Bcl-2) and BCL2-associated X (Bax) proteins, and reverse transcription polymerase chain reaction was used to analyze the expression of Bcl-2, Bax, p53, and caspase-3 messenger ribonucleic acid. An enzyme-linked immunosorbent assay was used to detect ROS levels in the parotid tissue. Results At each time point, the apoptotic rates in the irradiated group were higher than those in the control group. Furthermore, the ROS and expression levels of Bax, p53, and caspase-3 messenger ribonucleic acid and proteins gradually increased and were higher than those in the control group. Conversely, the expression of Bcl-2 was decreased in the irradiated group ( P < .05). Conclusions Ionizing radiation induces the production of ROS and promotes changes in the expression of several apoptotic proteins, which increases apoptosis and likely contributes to the mechanism of radiation-induced parotid injury.