IONIZING RADIATION-INDUCED EXPRESSION OF THE GENES ASSOCIATED WITH THE ACUTE RESPONSE TO INJURY IN THE RAT

Total-body irradiation of rats with doses ranging from an LD(10/30) to an LD(100/30) induced a dose-dependent increase in the concentration of serum protein associated with the acute response to the irradiation . However, this increase was reached at a later time and was not as pr onounced as described previously during the typical acute phase of the response found experimentally (A. Koj, in Structure and Function of P lasma Proteins, Vol. 1, pp. 73-131, Plenum Press, London, 1974). The g reatest increase in the serum concentrations of acute-phase proteins w as found from the third to the seventh days postirradiation. At these times, the serum concentrations of alpha(2)-macroglobulin, haptoglobin , fibrinogen and cysteine protease inhibitor were raised from two- to fivefold, whereas alpha(1)-acid glycoprotein was increased sixfold. In corporation of [S-35]methionine into total serum and acute-phase prote ins indicated that the increase in the concentration of the acute-phas e proteins was preceded by their de novo synthesis in the liver. The r esults that were obtained by dot-blot analysis showed that the basic c ourse of change in the relative mRNA concentrations in the liver for t he acute-phase proteins examined correlated with the changes in their protein concentrations in the serum; only the relative increase in the concentration of alpha(1)-acid glycoprotein mRNA was significantly lo wer than the increase in proteins in the serum, suggesting that a frac tion of the serum alpha(1)-acid glycoprotein had an extrahepatic origi n. On the basis of these results we concluded that total-body irradiat ion increased the expression of acute-phase protein genes. (C) 1995 by Radiation Research Society