[The nonmonotonicity changes of ornithine decarboxylase activity in spleen following exposure to gamma-irradiation on rats].
Exposure of rats to ionizing radiation caused in spleen nonmonotonous (as a function of time and of dose) changes in the activity of ornithine decarboxylase [ODC EC 4.1.1.17], an initial and rate limiting enzyme in polyamine synthesis. At physiological concentration polyamines (putrescine, spermidine, spermine) act as regulators of growth, proliferation and differentiation. ODC activity as well as spleen mass were studied in 2 h, 1, 7, 30 and 90 days after the exposure of rats to single-dose whole-body gamma-irradiation at the doses of 0.1, 1, 2, 6 Gy as well as 1, 7, 30, 90 day following fractionated one at a dose of 6 Gy (2 Gy three times in a week). Fractionating irradiation dose (2 Gy x 3) results in activation of ODC activity on day 30 after irradiation in contrast to the sharp decrease in the level of ODC activity on the same term after the single-dose exposure to gamma-irradiation at a dose of 6 Gy. The radiation activation of ODC precedes the renewal of organ mass. A possibility to apply a concept about nonmonotonic responses of mammalian cells and tissues to the action of ionizing radiation for analyzing dose-response processes of radiation damage and postradiation reparation of organism is discussed.
Fialkovskaia
L A
LA
Perepelkina
N I
NI
Kolomiĭtseva
I K
IK
D000818:Animals; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation; D008297:Male; D009955:Ornithine Decarboxylase / Q000096:biosynthesis* / Q000528:radiation effects*; D011073:Polyamines / Q000378:metabolism; D011839:Radiation, Ionizing; D051381:Rats; D017208:Rats, Wistar; D013154:Spleen / Q000201:enzymology / Q000528:radiation effects*; D013997:Time Factors
D011073:Polyamines; D009955:Ornithine Decarboxylase