Studies On Pathology And Regulation Mechanism Of Mice Bone Marrow Induced By Neutron And γ-ray Irradiation

Bone marrow is high sensitive to neutron irradiation. A little dose of neutron irradiation can cause severe injury of bone marrow. So far the dynamic observation and research on its pathological rule with modern molecular pathological techniques is unusual. In this experiment mice were used to replicate the animal model of bone marrow damage after radiation and to compare the pathological character and the role of caspase-3 and c-kit in bone marrow damage after exposed to different doses of neutron with y-ray. The techniques were needed such as light microscope, electron microscope, immunohistochemistry, DNA gel electrophoresis, in situ terminal end labeling, flow cytometry, and so on. Results: Intermediate and severe bone marrow radiation sickness suffered from the dead phase of hematopoietic cells, the remnant phase of bone marrow cells, regeneration and recovery phase and fundamental recovery phase while extremely severe bone marrow and gut radiation sickness suffered from the dead phase of hematopoietic cells, the remnant phase of bone marrow cells and the phase of hematopoietic cells vacuity. Apoptotic and necrotic cells increased obviously after neutron radiation, the more radiation dose was, the more necrotic cells, and the main death mode was necrosis in 5.5 Gy group, while apoptosis was the main death mode in y-rays irradiation, the more radiation dose was, the more apoptotic cells. C-kit protein expression increased obviously in cytoplasm of hematopoietic cells at 6h after neutron and y-ray irradiation, y-ray irradiation group stronger than neutron radiation group, c-kit protein expression showed positive on thehematopoietic cell membrane on 10d after γ-ray radiation, while positive on 14d after neutron radiation. Caspase-3 protein increased obviously at 6h in hematopoietic cells of both neutron and y-ray irradiated mice, which showed dose-effect relationship, namely, caspase-3 protein decreased with the increase of neutron radiation dose while increased with the increase of γ-ray radiation. Conclusions: 5.5Gy y-ray irradiation cause intermediate bone marrow radiation sickness, 2.5Gy neutron radiation cause severe bone marrow radiation sickness, while 4.0, 5.5Gy neutron radiation and 12Gy γ-ray irradiation cause gut radiation sickness. Neutron and y-ray radiation induced different death mode in hematopoietic cells: neutron radiation combine apoptosis with necrosis and the main death mode is necrosis in 5.5 Gy group, while apoptosis is the main death mode in y-rays irradiation. The gene expressions of c-kit and caspase-3 play an important role in the injury and repair of bone marrow cells.