Effect of ionizing radiation on the synthetic activity of blood system cells in ground squirrels in different physiological states

Abstract

The functional (synthetic) activity of blood lymphocytes and bone marrow haemopoietic cells in ground squirrels during the annual cycle as well as in hibernating and awaken animals in winter have been studied by fluorescent microspectrometry. The effect of ionizing radiation on animals in different functional states of the hibernation-arousal bout was investigated too. It was shown that the synthetic activity (parameter alpha) in blood lymphocytes was minimal in hibernating state in winter and maximal in active euthermic spring animals, then slightly decreased in June and more considerably decreased in the prehibernating autumn period. In awake animals in winter, the values of parameter alpha reached the same values as in summer. The changes of parameter alpha in bone marrow haemopoietic cells were essentially the same: the minimal values were observed in the prehibernation autumn period and in awake animals in winter the alpha values were slightly higher than in active euthermic animals in summer. The maximal synthetic activity in bone marrow haemopoietic cells in active euthermic spring animals is due mainly to cells in G1-G2 phases of the cell cycle. The decrease of the synthetic activity in summer is a result of the cell transition from G2 to mitosis and transition of a part of cells to G0 When investigating the hibernation-arousal bout in ground squirrels in winter, during arousal, we found two stages considerably differing in both the values of parameter alpha in bone marrow haemopoietic cells and the number of blood cells. The synthetic activity and the total number of blood and bone marrow cells in ground squirrels irradiated in the state of deep hibernation did not differ significantly from the state of non-irradiated hibernating animals. The negative effect of radiation appeared upon the arousal of these animals but it was expressed to a lesser degree in comparison with the animals irradiated in the active state. It was found that the acute irradiation of animals during arousal from hibernation in the second stage caused the most pronounced functional inactivation and cell death. The physiological state of ground squirrels subjected to ionizing irradiation at different phases of the hibernation-arousal bout plays a determining role in the changes of the qualitative and quantitative characteristics of blood system cells. Thus, the hypometabolic state of ground squirrels in hibernation is a factor of protection from the action of ionizing radiation on the organism and the immune system.