Regenerative capacity of normal and irradiated liver following partial hepatectomy in rats

Purpose: To investigate the regenerative capacity and proliferation related to cell cycle modulators in irradiated livers after partial hepatectomy (PH) in rats. Methods and materials: Two experimental groups were given a single dose of either 4-Gy or 8-Gy photon radiation to the whole liver following PH. The control group underwent only PH, without irradiation. The liver specimens were analysed for apoptosis, proliferation and cell cycle related genes between 0.5 and 12 days. Results: Mean change in weight of the remnant liver in the 8-Gy group was significantly lower than in the control and 4-Gy groups. The apex of proliferating cell nuclear antigen labelling and bromodeoxyuridine incorporation index in two irradiated groups were also apparently lower than that in control group. After PH, transforming growth factor beta-1 (TGF beta 1), and the type II receptor of TGF beta (TGF beta R-II), anti-tumour protein 53(p53) and anti-tumour protein21(p21) protein expression in the irradiated livers was higher than in unirradiated ones. Significant apoptosis was noted in 8-Gy group. However, the maximal value of hepatocyte growth factor (HGF) mRNA and protein expression in the irradiated group was suppressed and restoration of liver function was delayed. Conclusion: Whole liver lower dose irradiation can attenuate regenerative capacity following partial hepatectomy in rats.