Induction Of Apoptosis By Beta Radiation From Tritium Compounds In Mouse Embryonic Brain Cells

Abstract

Induction of apoptosis by tritium exposure was investigated in both cultured embryonic mid brain cells and brain sections of embryos and of newborns in mice. In the cultures of mid brain cells, addition of methyl-3H-thymidine (3H-TdR) (21 kBq mL(-1)) and tritiated water (5.616 MBq mL(-1)) induced late appearances and low percentages of apoptosis when compared to x-irradiation at the ID50 dose, the inhibitory dose that reduced cellular differentiation by 50% of the control. A significant increase in p53 protein was detected about 2 h before the marked appearance of apoptosis. The pregnant mice were given an intraperitoneal injection of tritiated water at the concentration of 481.8 kBq g(-1) of body weight on gestation day 12.5, by which treatment behavioral changes in the offspring occurred. Increased apoptotic cells were observed in the neural tube of embryos from 1 d after the injection to 1 wk postnatal age. Apoptosis induced by x-rays appeared 2 h after irradiation, with a peak at 4 h. Increase of apoptotic cells was also found in the brain cortexes of newborns. The percentage of apoptosis in the brain was higher in the prenatal tritiated water exposed mice than in the prenatal x-irradiated mice. Possible mechanisms on apoptosis and its relation to the higher relative biological effectiveness value of tritium beta-rays are discussed.

β Irradiation decreases collagen type II synthesis and increases nitric oxide production and cell death in articular chondrocytes

“…b Irradiation is also known to induce cell death (apoptosis) in various cell types or genetic damage through DNA strand breaks. [25][26][27] In our studies cell death in monolayer cultures might be caused by some sort of DNA strand breaks, because cell death was induced much more quickly in proliferating cell culture systems. Nevertheless, it might be speculated that some of the cell death that we found in our study might be related to NO induced apoptosis, 28 because NO is known to induce apoptosis in chondrocytes under certain circumstances.…”

3 H‐thymidine is a defective tool with which to measure rates of DNA synthesis

“…Although the damaging effects of cell‐incorporated low‐energy β‐emitting compounds such as 3 H‐TdR and 35 S‐methionine have been documented sporadically over the years (1–6, 15, 16, 18– 22), these radioactive metabolic tracers continue to be widely used in the biological sciences to study dynamic cell processes. Using a stable isotopic form of thymidine and mass spectrometry, we now show that 3 H‐TdR significantly inhibits the rate of DNA synthesis at all but the lowest conventional doses even in a short‐term assay covering only one round of replication.…”

Dragon's Blood May Have Radioprotective Effects in Radiation-Induced Rat Brain Injury

“…Ionizing radiation can damage the DNA, proteins and other macromolecules of central nervous system and can result in neuronal apoptosis, especially in the hippocampus (28)(29)(30)(31)(32)(33). Caspase 3 is activated at the early stages of apoptosis and generates two subunits of 17KD and 12KD.…”