Basic study on active changes in biological function of mouse liver graft in cold storage after low-dose x-irradiation

Abstract

We previously reported that low-dose X-irradiation alleviates ischemia-reperfusion injury such as mouse paw edema. In this study, we examined active changes in the biological function of mouse liver grafts in cold storage after low-dose X-irradiation. Mouse livers were sham-irradiated or were irradiated with 0.25, 0.5, 1.0, or 5.0 Gy of X-ray and stored for 4, 8, 24, or 48 h in preservation or saline solution. The results show that storage for 24 h in saline solution after 0.5 Gy irradiation significantly increased the activity of superoxide dismutase (SOD) and catalase. Following storage for 4, 8, or 48 h in preservation solution, lipid peroxide levels of the 0.5 Gy irradiated group were significantly lower than those of the sham irradiated group. Following storage for 24 h in preservation solution, the activity of SOD and catalase of the 1.0 Gy irradiated group were significantly higher than those of the sham irradiated group. Hepatocytes stored in saline solution were vacuolated. However, no vacuole formation was observed in hepatocytes stored in preservation solution. These findings suggest that low-dose irradiation significantly activates antioxidative functions of liver grafts. Moreover, the dose at which enhancement of antioxidative function occurs in livers stored in preservation solution, which contains glutathione, is significantly higher than that in saline solution.

Keywords: antioxidative function; hepatopathy; low-dose irradiation; organ transplantation.

Fig. 1

Changes in lipid peroxide levels of mouse livers in preservation after 0.5 Gy irradiation. Mouse livers were preserved in physiological saline or preservation solution for the indicated number of hours following sham irradiation of irradiation of 0.5 Gy as indicated. Lipid peroxide levels were measured with a commercial assay kit. Each value indicates the mean ± SEM. The number of mouse livers per experimental point is 5–10. *p<0.05, **p<0.01, ***p<0.001 vs control, ^#p<0.05, ^##p<0.01, ^###p<0.001 vs sham irradiation (storage in physiological saline solution).

Fig. 2

Changes in total glutathione content of mouse livers in preservation after 0.5 Gy irradiation. Mouse livers were treated as described for Fig. 1 and glutathione content was measured by a spectrophotometric assay. The data, number of mouse livers and significance are as described for Fig. 1.

Fig. 3

Changes in SOD activity of mouse livers in preservation after 0.5 Gy irradiation. Mouse livers were treated as described for Fig. 1 and SOD activity was measured by a spectrophotometric assay. The data, number of mouse livers and significance are as described Fig. 1.

Fig. 4

Changes in catalase activity of mouse liver in preservation after 0.5 Gy irradiation. Mouse livers were treated as described for Fig. 1 and catalase activity was measured by a spectrophotometric assay.The data, number of mouse livers and significance are as described Fig. 1.

Fig. 5

Changes in (A) lipid peroxide level, (B) glutathione content, and activities of (C) SOD and (D) catalase in mouse liver preserved for 24 h following irradiation. Mouse livers were treated as described for Fig. 1 and glutathione content was measured by a spectrophotometric assay. Each value indicates the mean ± SEM. The number of mouse livers per experimental point is 5–10. *p<0.05, **p<0.01, ***p<0.001 vs each solution by sham irradiation, ^#p<0.05, ^##p<0.01, ^###p<0.001 vs physiological saline solution.

Fig. 6

Histological changes in mouse liver in preservation after irradiation. Mouse livers were examined histologically following preservation under the following conditions. A) Control, B) Cold storage for 4 h in physiological saline solution after sham irradiation, C) Cold storage for 24 h in preservation solution after sham irradiation, D) Cold storage for 24 h in physiological saline solution after sham irradiation, E) Cold storage for 48 h in preservation solution after sham irradiation, F) Cold storage for 48 h in physiological saline solution after sham irradiation, G) Cold storage for 24 h in preservation solution after 1.0 Gy irradiation, and H) Cold storage for 24 h in physiological saline solution after 1.0 Gy irradiation. The arrow shows vacuole formation in the liver. The length of the scale bar is 20 µm. For all figures HE staining was used.