Cell stress response to low-dose neutron radiation

Background. It is a point of discussion whether low-dose ionizing radiation has harmful or stimulating impact on cell. According to high relative biological effectiveness of neutron radiation there is a need of description of any process triggered in the cell by neutrons.

Objective. The aim of current work is the investigation of the low dosed neutron radiation effects on human cells by indicators of cell stress such as state of chromatin and cell membrane permeability.

Materials and methods. Human buccal epithelium cells from 3 male donors (21, 24, 25 years old) were exposed to fast neutron radiation in dose range 2.3–146.0 mSv from ²³⁹Pu-Be source. State of chromatin was evaluated by count of heterochromatin granules quantity in 100 nuclei stained with 2% orcein in 45% acetic acid; ratio of cells with increased membrane permeability stained with 5 mM indigocarmine in 300 cells.

Results. Changes in level of heterochromatin granules quantity and in cell membrane permeability revealed wave-shaped dependency with maximum effects at 36.5 mSv. Further increase of dose resulted in return of both chromatin state and membrane permeability levels closely to control or even lower.

Conclusion. Membrane restoration and chromatin decompaction under doses higher than 36.5 mSv together can be a sign of hormetic (stimulating) effect of low-dose neutron radiation.