ABSTRACT
Experiments on mice irradiated with γ-rays in a wide range of doses, from 0.5 to 400 cGy and the bone marrow have shown cytogenetic and cytological effects ranging from I cGy dose 24 hours after exposure to radiation. Dose-independent reduction of the number of nucleated cells in the bone marrow, normal or even elevated levels of mitotic activity, and extreme dependence of the type of chromosomal aberrations on the radiation dose with the maximum in the region of 7.5 cGy were observed in the dose range from 1 to 20 cGy. A linear dose-dependent decrease of the cell.number in the bone marrow, a decreased mitotic activity and increased number of aberrant mitosis were marked in the dose range from 20 to 400 cGy. The findings are discussed in terms of their application for explaining the mechanisms of hormesis, adaptive response, as well as the appropriateness of accounting the parameters studied for solving problems of regulation of permissible doses.
Subject(s)
Bone Marrow Cells/radiation effects , Chromosome Aberrations/radiation effects , Cytogenetics , Mitosis/genetics , Animals , Bone Marrow Cells/cytology , Dose-Response Relationship, Radiation , Gamma Rays/adverse effects , Mice , Mitosis/radiation effects , Radiation DosageABSTRACT
Outbred CD-1 mice females aged 4 to 4.5-months were investigated in 21-22 hours following total γ-irradiation at 10, 25, 50, 75, 100 and 200 mGy. Loss in bone marrow karyocytes, as well as spleen and thymus mass reductions were significant in the group of animals irradiated at 50 and 200 mGy and less dramatic in mice irradiated at 75 mGy. The orientative-trying behavior reaction (OTBR) in the open field tested in 19-20 hours after exposure to 10 and 25 mGy was reliably stronger than in the group of biological control; however, emotional status (ES) in the animals that received 10 mGy dropped significantly. Mice irradiated at 50 mGy were found to weaken the grip of their front limbs. Dose levels differing in opposite radiobiological effects on the parameters under study were established. Doses in the range from 10 to 25 mGy maximized OTBR and ES, while doses of 50, 100 and 200 mGy produced high reactions of the immune and hemopoietic organs.
Subject(s)
Gamma Rays , Motor Activity/radiation effects , Radiation Injuries, Experimental/pathology , Radiation Tolerance/physiology , Animals , Dose-Response Relationship, Radiation , Male , Mice , Mice, Inbred ICRABSTRACT
The results of studying the mitotic activities and chromosomal aberrations in bone marrow cells from C57/BL6N mice with the help of the anaphase technique in 12 hours after completion of the 30-day "Bion-M1" mission and ground-based experiment using flight equipment are presented. A statistically reliable decline of the mitotic activity (0.74%) was found in cells taken from the space flown animals. In the ground-based experiment, a statistically reliable downward trend in proliferative activity (1.37%) was revealed after the comparison with groups of vivarium control (1.46-1.53%). In both experiments mice increased the number of initial mitotic phases (prophase + metaphase) relative to the sum of anaphases and telophases. The number of aberrant mitoses grew reliably in the group of flight animals by 29.7%, whereas in the ground-based experiment an upward trend was insignificant as their number increased up to 2.3% only. In the vivarium controls aberrant mitoses constituted 1.75-1.8%. An increase in chromosomal aberrations was largely due to such abnormalities as fragments. These findings seem to have been a result of summation of the effects of radiation and other stressful factors in space flight.
Subject(s)
Bone Marrow Cells/cytology , Cosmic Radiation/adverse effects , Mitosis/physiology , Space Flight , Animals , Bone Marrow Cells/pathology , Chromosome Aberrations , Cytogenetic Analysis , Male , Mice , Mice, Inbred C57BL , SpacecraftABSTRACT
The influence of light water with the reduced content of heavy stable isotopes of oxygen and hydrogen (deuterium) on the cytogenetic status of irradiated animals was investigated. In mice, hybrids of the first generation (CBA x C57B1) F1, the increase in the output (two-fold at the dose of 2 Gy) of aberrant mitoses in the cells of bone marrow and the decrease in the duration of the mitotic index of the first cellular cycle occurred under the influence of the two week maintenance before the irradiation on light water with ppm 35 obtained by the method of rectification as compared with the irradiated animals that were kept on the distilled water. It has been discovered that 24 h after irradiation the number of leukocytes in the group which consumed light water is lower than that in the animals that were contained on the distilled water. Moreover, the cellularity of the bone marrow in the group which consumed light water was higher than that in the animals that were contained on distilled water. The prolonged application of light water before irradiation (for 14 days) led to an increase in the sensitivity of the chromosomal apparatus of mice to γ-irradiation against the background of an increase in the mitotic activity of cells.
