Irradiation of cells in tissue culture

Abstract

Attempts were made to develop a method of characterizing the degree of radiation damage to neuronal cells in the absence of a vascular bed, using cultured explants from the dorsal root ganglion of the newborn rat. Cobalt-60 gamma irradiation doses to the culture chambers varied from 5000 to 10000 r, at dose rates of 1000 to 9500 r/min. Morphologic changes observed postirradiation were: reduction of the average cytoplasmic and nuclear areas, peripheral displacements of the nuclei, and alterations in cytoplasmic organization. At a dose of 7200 r, manifestations of injury to the neurons were not observed until at least a week after irradiation. However, at 20500 r, marked changes were seen within four days after irradiation. At 100000 r coriplete neuronal destruction occurred. Characteristic of the neuronal response to radiation was the individual variation of sensitivity: at 41000 r some neurons were found to exhibit nuclear rotation 42 days after exposure. Following irradiation the position of the nucleus in most neurons became peripheral or bulged partly or almost entirely out of the cell. This phenomeno increased in incidence following irradiation, especially at the higher dosages. The reduction of the mean cytoplasm area of neurons following a dose of 7200 rmore » is approximates 70% of the control values 10 days postirradiation. Following a dose of 20500 r a more marked and rapid reduction in the average cytoplasmic area occurred, dropping to about 50% of the unirradiated control values within three days. After this period, a more gradual fall was observed for 19 days postirradiation. At this dose, almost all neurons appeared to be damaged, although a few retained normal size and appearance. Morphological changes of the nuclei were not marked. However, a significant reduction in nuclear area was seen by 10 to 11 days postirradiation at survived for 10 days after 20500 r and about 5 to 10% survived after 41000 r. Less than 5% of neurons remained alive 20 to 30 days after 41000 r, and after 100000 r, given at 9500 r/min, all neurons were destroyed within four days. It is concluded that the extent of neuronal injury is dependent upon the dose of radiation received and the time elapsed after exposure. While the rnorphological effects observed may not be specific for radiation injury, they may serve as an indication of the degree of neuronal radiation damage. (BBB)« less