Effect of radiotherapy on experimental liver regenerative capacities following partial hepatectomy in rats

Objective: To investigate the regenerative capacities and proliferation related cytokines expression of normal and irradiated livers following 70% partial hepatectomy in rats. Methods: 90 male Sprague-Dawley rats were divided into 3 groups. The control group was only received 70% partial hepatectomy. The two irradiated groups were performed a single dose of 4 Gy and 8 Gy photon irradiation respectively followed 70% partial hepatectomy. The remanent liver were excised at 0.5,1.0,2.0,3.0,7.0 and 10.0 d after hepatectomy, and liver regeneration capacities in normal and irradiated rats were evaluated through remanent liver weigh, BrdU incorporation, PCNA labeling, and mitotic indices. The proliferation related cytokines expression were also compared. Results: After radiotherapy and hepatectomy 1 rats died of infection in control group, and two rats in 8 Gy group died of radiation induced enteritis. The original liver weigh is regained within 12 days in control and 4 Gy group, and proliferative speed was lower in 4 Gy group than control group. The weigh of remanent liver in 8 Gy group was significantly lower than the two groups all time points from 2d. The apex of PCNA labeling index was 80.2 ± 7.6%, 71.2 ± 6.5% and 55.3 ± 4.7% in control, 4 Gy and 8 Gy groups respectively at 2d, and 44.2 ± 5.4%, 35.3 ± 5.72% and 5.3 ± 6.9% with BrdU incorporation index. HGF mRNA expression peak of 4 Gy group was significantly lower than in control at 1 d, but no apparent peak value in 8 Gy group. TGF-β1 and TGF-βRII level of radiation groups was apparently higher than the control group at different time points. Meanwhile the p53 protein tend to increase at 1 d then decline with high expression in irradiated groups. Conclusion: Whole radiation can significantly inhibit the regenerative capacities following partial hepatectomy in rats with dose dependent. (authors)