Histologic assessment of regenerating rat liver under low-dose rate radiation exposure

In this study of the Wistar rats model, the partial hepatectomy (PH 1/3) as a mitogen was used to display radiation-induced damages in active dividing hepatocytes. Thus, 30-days total exposure in dose 0.78 cGy caused the significant decrease of the liver index (liver and total body weights ratio) by 1 and 30 days after PH. Histologic data show the high rate of binucleated hepatocytes 1, 2, 14, and 30 days after irradiation and PH and this could result in adaptive response to low-dose rate radiation. The effect of liver index decrease obviously occurs as a result of both high percentages of degenerating liver cells all days after exposure and registered structural changes in parenchyma (piecemeal necroses, pathologic mitoses, etc.). In comparison, we demonstrated high rate of degenerating hepatocytes in only irradiated animals 14 and 30 days after the radiation exposure as a result of long-term response of the slowly proliferating cells system. Consequently, the cells functional activity determines the development pace of the radiation-induced long-term effects. (c) 2004 Elsevier B.V. All rights reserved.