Keywords: ionising radiation, low dose, C57Bl/6J mice, glutathione, neuron loss, low radiation, chronic irradiation, hippocampus, brain cells, brain cell adaptation
Does a very low dose of chronic γ-irradiation induce a neuron loss in mice?
Little is known about the effects of a very low dose of chronic irradiation on the brain. We have analysed brain sections from continuously irradiated (10 cGy/year - γ-rays) and control C57Bl/6J mice at various times. We have established a neuron/astrocyte ratio in the CA1 of the hippocampus, measured the glutathione content of the hippocampus area and looked for the presence of PCNA-positive cells suggestive of immature stem cells. No difference was observed in the neurone/astrocyte ratio either with ageing or after irradiation. There was a significant increase in the glutathione content in the hippocampus area with ageing and after 24 months of irradiation. A slight increase of PCNA-positive cells was observed with ageing, especially after irradiation. These results suggest that a chronic very low dose of γ-irradiation does not induce a neuron loss. Increased levels of glutathione and of PCNA-positive cells may suggest an adaptation of brain cells to the radiation factor.