The Impact Of Radiation On The Rat Liver After Partial Hepatectomy Regenerative Capacity

Objective To investigate the regenerative capacities and proliferation related cytokines expression of normal and irradiated livers following 70%partial hepatectomy(PH) in rats.Methods Ninety 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 4Gy and 8 Gy irradiation respectively followed 70% partial hepatectomy.The remanet liver were excised at 0.5,1.0,2.0,3.0,7.0 and 12.0d after hepatectomy,and liver regeneration capacities in normal and irradiated rats were evaluated through remanet liver weigh,BrdU incorporation,PCNA labeling,and mitotic indices.The proliferation related cytokines expression were also measured using molecule biology technique,such as RT-PCR and Western-blotting.Results After radiotherapy and hepatectomy 1 rats died of infection in control group, and two rats in 8Gy group died of radiation induced enteritis.The original liver weigh is regained within 12 days in control and 4Gy group,and proliferative speed was lower in 4Gy group than control group.The weigh of remanet liver in 8Gy 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,4Gy and 8Gy groups respectively at 2d,and 44.2±5.4%,35.3±5.72%and25.3±6.9%with BrdU incorporation index.HGF mRNA expression apex of control group was apparently,,but the apex were not notable and delayed in 4Gy and 8Gy groups.The peak value of HGF mRNA expression in two irradiated groups were significantly lower than sham group.TGF-β₁ level mounts up after PH,attaines maximal value then declines.The value of two radiation groups was apparently higher than the control group at all time points.TGF-βRⅡmRNA and protein showed slight downtrend after PH in control group,and this trend was not observed in 4Gy group. However,TGF-βRⅡmRNA and protein expression present ascending trend. Meanwhile the maxmal value of p53 protein was at ld,then decline with high expression in irradiated groups.Conclusion The original liver weigh is regained within 12 days in control group, while the regenerative capacities following partial hepatectomy were significantly inhibited in the groups with the whole liver low dose irradiation.BrdU incorporation, PCNA labeling,and mitotic indices increase promptly after PH,indicating the strong regenerative capacity.In irradiated groups these indices were apparently lower than control group in different extent.Ascending trendline of positive modulation cytokines which hasten proliferation after PH in irradiated were lower than control group.Meanwhile cytokines of negative modulation show high expression in irradiated groups.